UFC 3-190-06 Protective Coatings and Paint.pdf

UFC 3-190-06

16 January 2004

UNIFIED FACILITIES CRITERIA (UFC)

PROTECTIVE COATINGS AND

PAINTS

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

UNIFIED FACILITIES CRITERIA (UFC)

PROTECTIVE COATINGS AND PAINTS

Any copyrighted material included in this UFC is identified at its point of use.

Use of the copyrighted material apart from this UFC must have the permission of the copyright holder.

U.S. ARMY CORPS OF ENGINEERS

NAVAL FACILITIES ENGINEERING COMMAND (Preparing Activity)

AIR FORCE CIVIL ENGINEER SUPPORT AGENCY

Record of Changes (changes are indicated by \1\ ... /1/)

Change No. Date Location 1 Dec 2005 FOREWORD

This UFC supersedes Military Handbook 1110, dated 30 September 1996.

FOREWORD

\1\ The Unified Facilities Criteria (UFC) system is prescribed by MIL-STD 3007 and provides planning, design, construction, sustainment, restoration, and modernization criteria, and applies to the Military Departments, the Defense Agencies, and the DoD Field Activities in accordance with USD(AT&L) Memorandum dated 29 May 2002. UFC will be used for all DoD projects and work for other customers where appropriate. All construction outside of the United States is also governed by Status of forces Agreements (SOFA), Host Nation Funded Construction Agreements (HNFA), and in some instances, Bilateral Infrastructure Agreements (BIA.)

Therefore, the acquisition team must ensure compliance with the more stringent of the UFC, the SOFA, the HNFA, and the BIA, as applicable.

UFC are living documents and will be periodically reviewed, updated, and made available to users as part of the Services’ responsibility for providing technical criteria for military construction. Headquarters, U.S. Army Corps of Engineers (HQUSACE), Naval Facilities Engineering Command (NAVFAC), and Air Force Civil Engineer Support Agency (AFCESA) are responsible for administration of the UFC system. Defense agencies should contact the preparing service for document interpretation and improvements. Technical content of UFC is the responsibility of the cognizant DoD working group. Recommended changes with supporting rationale should be sent to the respective service proponent office by the following electronic form: Criteria Change Request (CCR). The form is also accessible from the Internet sites listed below.

UFC are effective upon issuance and are distributed only in electronic media from the following source:

• Whole Building Design Guide web site http://dod.wbdg.org/.

Hard copies of UFC printed from electronic media should be checked against the current electronic version prior to use to ensure that they are current. /1/

AUTHORIZED BY:

DONALD L. BASHAM, P.E.

Chief, Engineering and Construction U.S. Army Corps of Engineers

DR. JAMES W WRIGHT, P.E.

Chief Engineer Naval Facilities Engineering Command

KATHLEEN I. FERGUSON, P.E.

The Deputy Civil Engineer DCS/Installations & Logistics Department of the Air Force

Dr. GET W. MOY, P.E.

Director, Installations Requirements and Management Office of the Deputy Under Secretary of Defense (Installations and Environment) http://www.wbdg.org/pdfs/ufc_implementation.pdf http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4 http://dod.wbdg.org/

CONTENTS

Page

CHAPTER 1 INTRODUCTION

Paragraph 1-1 PURPOSE AND SCOPE ....................................................... 1-1

1-2 APPLICABILITY..................................................................... 1-1 1-2.1 General Building Requirements ............................................. 1-1 1-2.2 Safety .................................................................................... 1-1 1-2.3 Fire Protection ....................................................................... 1-1 1-2.4 Antiterrorism/Force Protection ............................................... 1-1 1-3 REFERENCES ...................................................................... 1-1

APPENDIX A MIL-HDBK 1110……...…………...................…………………… A-1

i

CHAPTER 1

INTRODUCTION

1-1 PURPOSE AND SCOPE. This UFC is comprised of two sections.

Chapter 1 introduces this UFC and provides a listing of references to other Tri-Service documents closely related to the subject. Appendix A contains the full text copy of the previously released Military Handbook (MIL-HDBK) on this subject. This UFC serves as criteria until such time as the full text UFC is developed from the MIL-HDBK and other sources.

This UFC provides general criteria for protective coatings and paints.

Note that this document does not constitute a detailed technical design, maintenance or operations manual, and is issued as a general guide to the considerations associated with protective coatings and paints.

1-2 APPLICABILITY. This UFC applies to all Navy and Air Force service elements and contractors; Army service elements should use the references cited in paragraph 1-3 below; all other DoD agencies may use either document unless explicitly directed otherwise.

1-2.1 GENERAL BUILDING REQUIREMENTS. All DoD facilities must comply with UFC 1-200-01, Design: General Building Requirements. If any conflict occurs between this UFC and UFC 1-200-01, the requirements of UFC 1-200-01 take precedence.

1-2.2 SAFETY. All DoD facilities must comply with DODINST 6055.1 and applicable Occupational Safety and Health Administration (OSHA) safety and health standards.

NOTE: All NAVY projects, must comply with OPNAVINST 5100.23 (series), Navy Occupational Safety and Health Program Manual. The most recent publication in this series can be accessed at the NAVFAC Safety web site:

www.navfac.navy.mil/safety/pub.htm. If any conflict occurs between this UFC and OPNAVINST 5100.23, the requirements of OPNAVINST 5100.23 take precedence.

1-2.3 FIRE PROTECTION. All DoD facilities must comply with UFC 3-600-01, Design: Fire Protection Engineering for Facilities. If any conflict occurs between this UFC and UFC 3-600-01, the requirements of UFC 3-600-01 take precedence.

1-2.4 ANTITERRORISM/FORCE PROTECTION. All DoD facilities must comply with UFC 4-010-01, Design: DoD Minimum Antiterrorism Standards for Buildings. If any conflict occurs between this UFC and UFC 4-010-01, the requirements of UFC 4-010-01 take precedence.

1-1

1-3 REFERENCES. The following Tri-Service publications have valuable information on the subject of this UFC. When the full text UFC is developed for this subject, applicable portions of these documents will be incorporated into the text. The http://www.navfac.navy.mil/safety/pub.htm designer is encouraged to access and review these documents as well as the references cited in Appendix A.

1. US Army Corps of Engineers AFETL 96-5, Hangar Concrete Floor

Commander Reflective Coating Criteria, 26 August USACE Publication Depot 1996 ATTN: CEIM-IM-PD USACE EM 1110-2-3400, Painting:

2803 52nd Avenue New Construction and Maintenance Hyattsville, MD 20781-1102 USACE TM 5-618, Paints and

(301) 394-0081 fax: 0084 Protective Coatings, 15 June 1981 karl.abt@hq02.usace.army.mil http://www.usace.army.mil/inet/usace-docs/

1-1 mailto:karl.abt@hq02.usace.army.mil http://www.usace.army.mil/inet/usace-docs/

APPENDIX A

MIL-HDBK 1110

PROTECTIVE COATINGS AND PAINTS

A-1

1.

NOT MEASUREMENT

SENSITIVE

MIL-HDBK-1110

17 JANUARY 1995

SUPERSEDING

NAVFAC MO-110

JUNE 1981

MILITARY HANDBOOK

HANDBOOK FOR PAINTS AND PROTECTIVE COATINGS

FOR FACILITIES

AMSC N/A AREA FACR

DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.

ABSTRACT

This handbook is provided as guidance for DOD personnel wishing to apply architectural paints or protective coatings to military structures fixed in place. It is not for use with ships, aircraft, or automotive vehicles. It is written for general use by both those with much and with little knowledge of the use of paint and coating materials. It contains information on the composition of coatings, their mechanisms of curing, environmental and safety concerns, necessary surface preparation, selection for different substrates and structures, application, inspection, and failure analysis.

ii

FOREWORD

This handbook identifies criteria and procedures for applying architectural paints or protective coatings to military structures fixed in place.

Recommendations for improvements are encouraged from Government agencies and the private sector and should be furnished on the DD Form 1426 provided inside the back cover to Commanding Officer, Northern Division, Naval Facilities Engineering Command, Code 164, 10 Industrial Highway, Mail Stop 82, Lester, PA 19113-2090;

Telephone: Commercial (610) 595-0661/DSN 443-0661.

THIS HANDBOOK SHALL NOT BE USED AS A REFERENCE DOCUMENT FOR

PROCUREMENT OF FACILITIES CONSTRUCTION. IT IS TO BE USED AS A

MAINTENANCE MANAGEMENT TOOL BY PUBLIC WORKS DEPARTMENTS, PUBLIC

WORKS CENTERS, BASE CIVIL ENGINEERS, AND FACILITIES ENGINEERS.

DO NOT REFERENCE IT IN MILITARY OR FEDERAL SPECIFICATIONS OR

OTHER PROCUREMENT DOCUMENTS.

iii

THIS PAGE INTENTIONALLY LEFT BLANK

iv

HANDBOOK FOR PAINTS AND PROTECTIVE COATINGS FOR FACILITIES

CONTENTS

Page Section 1 INTRODUCTION

1.1 Purpose

1.2 Scope

1.3 Deterioration of Facilities

1.3.1 Corrosion of Metals

1.3.2 Deterioration of Wood

1.3.3 Deterioration of Concrete

1.3.4 Design Factors Affecting Deterioration

1.3.4.1 Water Traps

1.3.4.2 Crevices

1.3.4.3 Rough and Sharp Surfaces

1.3.4.4 Limited Access to Work

1.3.4.5 Incompatible Environment

1.3.4.6 Contact of Dissimilar Metals

1.4 Control of Facilities Deterioration

1.4.1 Corrosion Control by Coatings

1.4.1.1 Barrier Protection

1.4.1.2 Inhibitive Pigments

1.4.1.3 Cathodic Protection

1.5 Painting for Purposes Other Than Protection 5

1.5.1 Cosmetic Appearance

1.5.2 Marking Paints

1.5.3 Safety Colors and Designs

1.5.4 Reflective Finishes

1.5.5 Nonskid Surfaces

1.5.6 Antifouling Coatings

Section 2 COATING COMPOSITIONS AND CURING MECHANISMS

2.1 Coating Composition

2.1.1 Solvent

2.1.2 Resin

2.1.3 Pigment

2.1.4 Other Components

2.1.5 Spreading Rate

2.2 Mechanisms of Curing of Coatings

2.2.1 Air Oxidation of Drying Oils

2.2.2 Solvent of Water Evaporation

2.2.3 Chemical Reaction

2.3 Properties of Different Generic Types

of Coatings

2.3.1 Alkyds and Other Oil-Containing Coatings... 14

2.3.2 Water Emulsion (Latex) Coatings

2.3.3 Lacquers

2.3.4 Epoxy Coatings

v

2.3.5 Coal-Tar Epoxy Coatings

2.3.6 Polyurethane Coatings

2.3.7 Polyester Coating

2.3.8 Inorganic Zinc Coatings

2.3.9 Zinc-Rich Organic Coatings

2.4 Coating Compatibility

2.4.1 Bleeding

2.4.2 Disbonding of Old Paint

2.4.3 Topcoat Checking

2.4.4 Poor Adhesion of Latex Topcoats to Enamels.. 21

2.4.5 Oil-Based Paints Applied to Alkaline

Surfaces

Section 3 ENVIRONMENTAL, OCCUPATIONAL, AND SAFETY ISSUES

3.1 Introduction

3.2 Material Composition Issues

3.2.1 VOC Restrictions

3.2.1.1 Definition of VOC

3.2.1.2 Types of Regulations

3.2.1.3 Effect on Coatings

3.2.2 Application Issues

3.2.3 Toxic Solvents

3.2.4 Hazardous Air Pollutants

3.2.5 Binders - Polyurethanes, Coal Tars, Asphalts 26

3.2.6 Heavy Metal-Containing Pigments and

Additives

3.3 Issues Affecting Surface Preparation

3.3.1 Regulations

3.3.2 Waste

3.4 Surfaces Coated With Leaded Paint

3.4.1 Background

3.4.1.1 Use of Lead in Paint

3.4.1.2 Effects of Lead Exposure on Health

3.4.1.3 Environmental Issues

3.4.1.4 Occupational Safety Issues

3.4.2 Definitions

3.4.3 DOD Policy/Instruction

3.4.3.1 Residential Structures

3.4.3.2 Non-Residential

3.4.4 General Description of Lead-Based Paint

Procedures

3.4.4.1 Inspection/Assessment

3.4.4.2 In-Place Management (IPM)

3.4.4.3 Removal

3.4.4.4 Operations and Maintenance

3.4.5 Waste Disposal

3.4.6 Demolition of Buildings Containing

Lead-Based Paint

3.4.7 Sources of Detailed Information

vi

MIL-HDBK-lll0

Section 4 SELECTION OF COATINGS

4.1 Available Guidance

4.2 Selection Criteria

4.2.1 Desired Film Properties

4.2.2 Work Requirements or Limitations

4.2.3 Safety and Environmental Restrictions

4.2.4 Compatibilities

4.2.5 Costs

4.3 Specifications for Lead- and Chromate-Free

Coatings With VOC Limits

4.4 Recommendations for Different Substrates... 39

4.4.1 Recommendations for Wood

4.4.1.1 Oil-Based Paints

4.4.1.2 Water-Emulsion Paints

4.4.1.3 Semi-Transparent Stains

4.4.1.4 Clear Floor Finishes

4.4.2 Recommendations for Concrete and Masonry

Surfaces

4.4.2.1 Waterborne Coatings

4.4.2.2 Elastomeric Coatings

4.4.2.3 Textured Coatings

4.4.2.4 Epoxy Coatings

4.4.3 Recommendations for Steel

4.4.3.1 Alkyd Systems

4.4.3.2 Epoxy Coating Systems

4.4.3.3 Zinc-Rich Coatings

4.4.4 Recommendations for Galvanized Steel

4.4.4.1 Epoxy Systems

4.4.4.2 Waterborne System for Galvanizing

4.4.5 Recommendations for Aluminum

Section 5 COATING SYSTEMS FOR SPECIFIC USES

5.1 General

5.2 Painting New Construction

5.3 Fuel Storage Tanks

5.3.1 Interiors of Steel Fuel Tanks

5.3.2 Exteriors of Steel Fuel Tanks

5.4 Steel Water Tanks

5.4.1 Interiors of Steel Water Tanks

5.4.2 Exteriors of Steel Water Tanks

5.5 Other Steel Tanks

5.5.1 Interiors of Other Steel Tanks

5.5.2 Exteriors of Other Steel Tanks

5.6 Steel Distribution Lines

5.6.1 Steel Fuel Lines

5.6.1.1 Buried Steel Fuel Lines

5.6.1.2 Immersed Steel Fuel Lines

5.6.1.3 Aboveground Fuel Lines

vii

5.6.2 Steel Water Distribution Lines

5.7 Communication Towers and Other Tall

Structures

5.7.1 New Towers

5.7.1.1 New Galvanized Steel Towers

5.7.1.2 New Thermally Sprayed Steel Towers

5.7.1.3 New Steel Towers

5.7.2 Existing Towers

5.7.2.1 Towers With Only Cosmetic Coating Defects... 56

5.7.2.2 Zinc-Coated Steel Tower Components With

Deteriorated Organic Coatings

5.7.2.3 Steel Tower Components (With No Zinc

Coating) With Damaged Organic Coating

5.7.3 Galvanized Steel Guy Lines for Towers

5.8 Waterfront Structures

5.9 Hydraulic Structures and Appurtenant Works.. 58

5.10 Factory Finished Metal Siding

5.11 Chain Link Fences

5.12 Hot Steel Surfaces

5.13 Concrete Fuel Tanks

5.14 Concrete Swimming Pools

5.15 Concrete Catchment Basins

5.16 Chemically Resistant Finishes for Concrete

Floors

5.17 Slip-Resistant Floors

5.18 Fouling-Resistant Coatings

5.19 Mildew-Resistant Coatings

5.19.1 Factors Affecting Mildew Growth

5.19.2 Use of Mildewcides in Paints

5.19.3 Removal of Mildew

5.20 Pavement Markings

5.20.1 Painted Markings

5.20.1.1 Specifications for Marking Paints

5.20.1.2 Specification for Reflective Glass Beads

5.20.1.3 Application of Painted Markings

5.20.1.4 Inspection of Marking Operation

5.20.2 Alternative Markings

5.21 Wooden Floors

Section 6 SURFACE PREPARATION

6.1 Introduction

6.1.1 Selection Factors

6.1.2 Specification Procedure

6.1.3 Section Organization

6.2 Repair of Surfaces

6.2.1 Joints, Cracks, Holes, or Other Surface

Defects viii

6.2.2 Cementitious Surfaces

6.3 Recommendations By Substrate

6.3.1 Wood

6.3.2 Concrete/Masonry

6.3.3 Steel

6.3.3.1 Specific Surface Preparation Requirements

for Coatings for Steel

6.3.4 Galvanized and Inorganic-Zinc Primed Steel.. 77

6.3.5 Aluminum and Other Soft Metals

6.4 Standards for Condition of Substrates

6.4.1 Unpainted Steel

6.4.2 Nonferrous Unpainted Substrates

6.5 Standards for Cleanliness of Substrates

6.5.1 Standards for Cleaned Steel Surfaces

6.5.1.1 SSPC and NACE Definitions and Standards

6.5.1.2 Job-Prepared Standard

6.5.1.3 Pictorial Standards for Previously Painted

Steel

6.5.2 Standards for Cleaned Nonferrous Metals

6.5.3 Previously Coated Surfaces

6.6 Recommendations for Paint Removal

6.7 Methods of Surface Preparation

6.7.1 Abrasive Blasting

6.7.1.1 Types of Abrasive Blasting

6.7.1.2 Conventional Abrasive Blasting Equipment

6.7.1.3 Abrasive Properties

6.7.1.4 Abrasive Types

6.7.1.5 Selection

6.7.1.6 Inspection

6.7.1.7 Procedures/General Information

6.7.2 Acid Cleaning

6.7.2.1 Concrete

6.7.3 Chemical Removal of Paint

6.7.4 Detergent Washing

6.7.5 Hand Tool Cleaning

6.7.6 Heat

6.7.7 Organic Solvent Washing

6.7.8 Power Tool Cleaning

6.7.9 Steam Cleaning

6.7.10 Water Blast Cleaning

6.7.10.1 Equipment

Section 7 APPLICATION

7.1 Introduction

7.2 Paint Storage Prior to Application

7.3 Preparing Paint for Application

7.3.1 Mixing

7.3.1.1 Mixing Two-Component Coatings

ix

7.3.2 Thinning

7.3.3 Tinting

7.3.4 Straining

7.4 Weather Conditions Affecting Application

of Paints

7.4.1 Temperature

7.4.2 Humidity

7.4.3 Wind

7.4.4 Moisture

7.5 Methods of Application

7.5.1 Selection of Application Method

7.5.2 Brush Application

7.5.2.1 Procedure for Brush Application

7.5.3 Roller Application

7.5.3.1 Procedures for Roller Application

7.5.4 Spray Application

7.5.4.1 Conventional or Air Spray Equipment

7.5.4.2 Airless Spray

7.5.4.3 Air-Assisted Airless Spray

7.5.4.4 High-Volume, Low-Pressure Spray

7.5.4.5 Multi-Component Spray

7.5.4.6 Electrostatic Spray

7.5.4.7 Powder Spraying

7.5.4.8 Thermal Spraying

7.5.4.9 Application Technique

Section 8 PREPARATION OF A PAINTING CONTRACT

SPECIFICATION

8.1 General

8.2 Background

8.3 The CSI Format

8.3.1 General Information Part

8.3.1.1 Summary Section

8.3.1.2 Reference Section

8.3.1.3 Definition Section

8.3.1.4 Submittals Section

8.3.1.5 Quality Assurance Section

8.3.1.6 Delivery, Storage, Handling, and Disposal..133

8.3.1.7 Site Conditions

8.3.2 Products Part

8.3.3 Execution Part

8.3.3.1 Work Conditions

8.3.3.2 Surface Preparation

8.3.3.3 Coating Application

8.3.3.4 Inspection

8.4 Language to be Used in Specification

8.4.1 Concise Words

8.5 Construction Criteria Base

x

Section 9 INSPECTION OF PAINTING OPERATIONS

9.1 Scope of Section

9.2 Importance of Inspection

9.3 Contractor Quality Control Inspection

9.4 Duties of an Inspector

9.4.1 Record Keeping

9.5 Inspection Equipment

9.6 Inspection Steps

9.6.1 Review Specification and Correct

Deficiencies, If Any

9.6.2 Visit Job Site

9.6.3 Conduct Pre-Construction Conference

9.6.4 Inspect Job Site After Pre-Surface

Preparation

9.6.5 Inspect Coating Materials

9.6.6 Measure Ambient Conditions

9.6.6.1 Relative Humidity and Dew Point

9.6.6.2 Surface Temperature

9.6.7 Inspect Surface Preparation

9.6.7.1 Abrasive-Blasting Surface Preparation

Equipment and Supplies

9.6.7.2 Water Blasting

9.6.7.3 Frequency of Inspecting Cleaned Surfaces

9.6.7.4 Inspecting Prepared Steel Surfaces

9.6.7.5 Inspecting Concrete, Masonry, Wood, Plaster, Wallboard, Old Paint

9.6.8 Inspect Coating Application

9.9.8.1 Application Equipment

9.6.8.2 Ventilation

9.6.8.3 Mixing/Thinning

9.6.8.4 Film Thickness

9.6.8.5 Drying

9.6.9 Final Approval Procedures

9.6.10 Year Warranty Inspection

Section 10 FIELD INSPECTION INSTRUMENTS

10.1 Introduction

10.2 Illuminated Microscope

10.3 Instruments for Use with Abrasive Blasting..156

10.3.1 Gage for Determining Nozzle Pressure

10.3.2 Wedge for Determining Diameter of Nozzle

Orifice

10.3.3 Surface Contamination Detection Kit

10.3.4 Profile of Blasted Steel

10.3.4.1 Comparators

10.3.4.2 Surface Profile Gages

10.3.4.3 Testex Press-O-Film Replicate Tape

10.3.5 Thermometers

10.3.6 Psychrometers

xi

10.3.7 Wind Meter

10.3.8 Moisture Meter

10.3.9 Wet Film Gage

10.3.9.1 Notched Metal Gage

10.3.9.2 Cylindrical Gage

10.3.10 Dry Film Thickness Gages for Coatings on

Aluminum, Copper, and Stainless Steel

10.3.11 Magnetic Dry Film Thickness Gages for

Coatings on Steel

10.3.11.1 Pull-Off Gages

10.3.11.2 Flux Gages

10.3.12 Destructive (Nonmagnetic Dry Film Thickness

Gage)

10.3.13 Holiday Detector

10.3.13.1 Low Voltage Holiday Detectors

10.3.13.2 High Voltage Holiday Detectors

10.3.14 Adhesion Tester

10.3.14.1 Tape Adhesion Test

10.3.14.2 Pull-Off Adhesion Test

10.3.15 Portable Glossmeter

10.3.16 Hardness Tester

Section 11 ANALYSIS OF PAINT FAILURES

11.1 Definition

11.2 Documentation of Findings

11.3 Scope of Failure Analysis

11.3.1 Review of Specification for Coating Work

11.3.2 Review of Supplier’s Data

11.3.3 Review of Inspector’s Daily Reports

11.3.4 On-Site Inspection

11.3.5 On-Site Inspection Techniques

11.3.6 Laboratory Testing

11.3.6.1 Microscopic Examination

11.3.6.2 Spot Tests

11.3.6.3 Infrared Spectrophotometric Analysis

11.3.6.4 Other Specialized Instrumentation

11.3.7 Forming Conclusions and Preparing Reports...169

11.4 Expert System for Failure Analysis

11.4.1 Cosmetic Defects

11.4.1.1 Chalking

11.4.1.2 Mildew

11.4.1.3 Dirt

11.4.1.4 Uneven Gloss

11.4.1.5 Blushing

11.4.1.6 Bleeding

11.4.1.7 Fading

11.4.1.8 Discoloration

xii

11.4.1.9 Pigment Overload

11.4.1.10 Checking

11.4.1.11 Dry Spray

11.4.1.12 Sagging

11.4.1.13 Orange Peel

11.4.1.14 Wrinkling

11.4.2 Film Failures

11.4.2.1 Crawling

11.4.2.2 Alligatoring

11.4.2.3 Intercoat Delamination

11.4.2.4 Intercoat Blistering

11.4.2.5 Pinpoint Rusting

11.4.2.6 Cracking

11.4.2.7 Blistering to Substrate

11.4.2.8 Peeling

11.4.2.9 Flaking (Scaling)

11.4.3 Examples of Using Decision Trees

11.4.3.1 Example of Surface Defect

11.4.3.2 Example of a Film Defect

Section 12 PROGRAMMING MAINTENANCE PAINTING

12.1 Definitions of Programmed Painting and

Maintenance Painting

12.2 Components of Programmed Painting

12.2.1 Initial Design

12.2.1.1 Structural Design

12.2.1.2 Design of Coating System

12.2.2 Plan for Monitoring Conditions of

Structures and Their Protective Coatings

12.2.2.1 Determining the Type of Coating Failure

12.2.2.2 Determining the Extent of Coating Failure...177

12.2.2.3 Determining the Generic Type of the Finish

Coat

12.2.3 Types of Maintenance Painting

12.2.4 Plan for Maintenance Painting

12.2.4.1 Selecting Materials for Maintenance

Painting

12.2.4.2 Surface Preparation for Maintenance

Painting

12.2.4.3 Application for Maintenance Painting

12.2.4.4 Inspection of Maintenance Painting

12.2.5 Scheduling the Work

Section 13 GENERAL SAFETY PRACTICES DURING PAINTING

OPERATIONS

13.1 Introduction

13.2 Standard Operation and Safety Plans

xiii

13.3 Hazard Communication

13.3.1 Labels

13.3.2 Material Safety Data Sheets

13.4 Toxicity Hazards

13.4.1 Entrance of Toxic Materials Into Body

13.4.1.1 Inhalation

13.4.1.2 Ingestion

13.4.1.3 Skin Absorption

13.4.2 Types of Toxic Materials

13.5 Respiratory Hazards

13.6 Hazards in Different Painting Operations

13.6.1 Surface Preparation

13.6.1.1 Abrasive and Water Blasting

13.6.1.2 Mechanical Cleaning

13.6.1.3 Chemical Cleaning

13.6.1.4 High Temperature Operations

13.6.2 Painting Operations

13.6.2.1 Storage of Paints

13.6.2.2 Mixing and Applying Paints

13.6.3 Work in High, Confined, and Remote Places...189

13.6.3.1 Work in High Places

13.6.3.2 Confined Areas

13.6.4 Remote Areas

13.7 Personal Protective Equipment

13.7.1 Clothing

13.7.1 Gloves

13.7.2 Protective Headwear

13.7.2.1 Hard Hats

13.7.2.2 Bump Hats

13.7.2.3 Hair Covers

13.7.3 Eye Protection

13.7.3.1 Safety Glasses

13.7.3.2 Safety Goggles

13.7.3.3 Safety Shields

13.7.4 Hearing Protection

13.7.4.1 Ear Muffs

13.7.4.2 Ear Plugs

13.7.4.3 Canal Cups

13.7.5 Safety Shoes

13.7.6 Respirators/Ventilation

13.8 Safety Program

FIGURES

Figure 1 Schematic Drawing Illustrating Components of Conventional Abrasive Blasting Equipment. 83 xiv

Figure 2 Schematic Drawing of Cross Section of Typical Water-Injected Wet Abrasive Blasting Nozzle Figure 3 Cross-Sectional Drawing of Nozzles Figure 4 Drawing Illustrating Effect of Shape of Abrasive Particle on Contour of Blast- Cleaned Metallic Substrate Figure 5 Schematic Illustrating Typical Cleaning Angles for Various Surface Conditions Figure 6 Illustration of Proper Stroke Pattern for Blast Cleaning Figure 7 Illustration of Mixing and “Boxing” One- Component Paint: A - Pouring Off Pigment- Poor Vehicle, B and C - Mixing Pigment to Form Smooth Paste, D - Pouring in Vehicle and Mixing, E - Boxing Paint Figure 8 Illustration of Parts of Paint Brush Figure 9 Equipment Used in Applying Paint by Roller..108 Figure 10 Schematic Drawing Illustrating Basic Parts of Conventional Air Spray Application Equipment Figure 11 Drawing of Air-Spray Gun Figure 12 Cross-Sectional Drawing of Nozzle of Air- Spray Gun Figure 13 Illustration of Proper Spray Patterns Figure 14 Illustration of Improper Movement of Spray Gun When Applying Paint Figure 15 Illustration of Proper Procedure for Spray Painting Large Flat Surfaces Figure 16 Schematic to Illustrate Proper Painting of Large Vertical Surfaces Figure 17 Illustration of Proper “Triggering” of Spray Guns Figure 18 Proper Spray Painting of Inside Corners Figure 19 Proper Spray Painting of Outside Corners Figure 20 Schematic Illustrating Importance of Spraying Surfaces With Protruding Parts From All Directions to Avoid “Shadowing Effect” Figure 21 Sample Inspector’s Contract Summary Form Figure 22 Sample Daily Project Reports for Painting Inspectors Figure 23 Nomograph for Estimating Quantities of Paint Required for a Job Figure 24 Decision Tree 1: Support for Analysis of Coating Failures That Do Not Penetrate the Finish Coat xv

Figure 25 Decision Tree 2: Support for Analysis of Coating Defects That Penetrate the Finish Coat Figure 26 Coating Condition and Identification Form..179

TABLES

Table 1 Compatibility of Commonly Used Paints Table 2 Problems Encountered With Low VOC Coatings. 25 Table 3 TLV and Other Safety Data on Paint and Cleaning Solvents Table 4 DOD and Military Component’s Policy Documents on Lead-Based Paint Table 5 Lead- and Chromate-Free Coating Specifications With VOC Limits Table 6 Commonly Used Methods of Surface Preparation for Coatings Table 7 SSPC and NACE Standards for Cleaned Steel Surfaces Table 8 Procedures for Coating Removal Table 9 Typical Physical Characteristics of Abrasives Table 10 Approximate Rates of Paint Application Table 11 Comparison of Conventional Air and Airless Spray Table 12 Common Conventional Air-Spray Problems and Their Causes and Remedies Table 13 Common Airless-Spray Problems and Their Causes and Remedies Table 14 Spray Painting Errors Table 15 Equipment for Inspecting Painting Operations Table 16 Inspection Steps

REFERENCES

GLOSSARY

xvi

Section 1: INTRODUCTION

1.1 Purpose. This handbook presents information on the

effective use of paint-type coatings to protect metal, concrete, and wooden structures at military activities from deterioration.

In this handbook, the words "paint" and "coating" are used interchangeably. Sometimes, the word "paint" is used to describe an architectural rather than protective material, but this is not the case in this handbook.

1.2 Scope. This handbook covers virtually all aspects of

coating fixed structures. These include surface preparation for painting; selection, application, and inspection of coatings for both original and maintenance painting; quality control methods and equipment; and painting different substrates and facilities.

It does not cover painting of ships, aircraft, or motor vehicles.

The coatings covered are limited to organic paint-type materials, with a few exceptions. Inorganic zinc, thermal spray metal, and powder coatings are included, because they are most commonly used as alternatives to conventional organic coatings and, like organic coatings, are usually applied by spray.

1.3 Deterioration of Facilities. The main purpose of

painting military facilities is to protect them from deterioration. These structures comprise a vital resource in the defense of our nation. They must be kept in a state of operational readiness by efficient use of the limited funds available for this purpose. Unfortunately, these facilities are frequently subject to environments and uses that accelerate their natural deterioration and require costly repairs and maintenance.

Metals corrode in aggressive soil, industrial or chemical atmospheres, or immersion environments; woods swell, warp, and crack during weathering; concrete and masonry structures crack and spall in severe environments; and organic polymeric materials suffer degradation in sunlight. To adequately meet the challenges of protecting constructed facilities, it is necessary to have a general understanding of the common ways in which materials deteriorate and the procedures used to control the deterioration.

1.3.1 Corrosion of Metals. Metals corrode because they exist

in chemically unstable states. Thus, iron ore is a corrosion product in its natural, stable state. Energy must be used in blast furnaces to reduce iron to its metallic state. Iron and steel products are then slowly oxidized by corrosion to their previous stable lower energy states. Four conditions must be present for corrosion to occur:

a) Anodic areas where corrosion occurs

b) Cathodic areas where the metal is protected

c) An electrolyte (conductive medium such as soil or water)

d) A metallic path between the anode and cathode

In atmospheric corrosion, surface moisture and contamination serve as the electrolyte. Dissimilar metals are anodic and cathodic to each other; also, the same metal components have anodic and cathodic areas because of slight chemical or physical differences.

1.3.2 Deterioration of Wood. The chief causes of

deterioration of wood are effects of ultraviolet light, and swelling and contracting. These adversely affect the physical properties of the wood.

1.3.3 Deterioration of Concrete. The chief cause of concrete

deterioration is moisture and electrolyte penetration. This may result in deterioration of the concrete itself or in corrosion of reinforcing steel which causes spalling of the concrete.

1.3.4 Design Factors Affecting Deterioration. Poor design of

structures may accelerate their deterioration or interfere with their protection by coatings. Examples of poor designs are listed below:

a) Water traps

b) Crevices

c) Rough and sharp surfaces

d) Limited access

e) Incompatible environment

f) Contact of dissimilar metals

1.3.4.1 Water Traps. Since water greatly accelerates

deterioration, structures should be designed so that water is not collected. For example, angle irons and other configurations that can collect water should be oriented downward rather than upward. Weep holes of sufficient size should be placed where water collection cannot be otherwise avoided. Condensate water from air conditioners should not be allowed to run or drip on surfaces and steam or other vapors should not be allowed to impinge on surfaces.

1.3.4.2 Crevices. Crevices should be avoided in structures, because these oxygen-deficient areas accelerate metal corrosion.

Thus, continuous welds should be used rather than skip welds.

Back-to-back angles should also be avoided for this reason.

1.3.4.3 Rough and Sharp Surfaces. To obtain protection of a

surface, a painter must be able to apply a uniformly thick, continuous film. Thus, irregular surfaces such as welds and other projections should be ground smooth to eliminate projections through the paint film. Weld-spatter, which is loosely-bonded to the steel, must be removed for two reasons. First, it creates crevices which lead to crevice corrosion and, second, as the mill scale becomes disbonded, the barrier film will be broken.

Sharp edges should be rounded (1/8 inch or more radius is ideal) because a uniformly thick coating cannot be applied over the edge. This is because wet coatings draw thin on them.

Sharp interior corners should be avoided, since they may receive an excessive coating thickness.

1.3.4.4 Limited Access to Work. Areas to be protected should

be readily accessible for inspection and maintenance. Difficult-to-reach areas are not only difficult to prepare and coat, but reaching them may also constitute a safety hazard.

1.3.4.5 Incompatible Environment. Materials must be compatible with the environment in which they are located. Thus, aluminum should not come into direct contact with concrete, because the alkalinity of the concrete will attack the aluminum.

1.3.4.6 Contact of Dissimilar Metals. Dissimilar metals

probably present the biggest design problem. Because they have different corrosion potentials, they may corrode rapidly when in contact with each other. Examples of dissimilar metal (galvanic) corrosion are:

a) Steel pipe passing through an aluminum deck

b) Steel nut on a copper valve

c) Aluminum stanchion with a bronze lifeline

d) Aluminum plate with steel or different alloy aluminum rivets

e) Mild steel attached to stainless steel

Dissimilar surface conditions (e.g., threads, scratches, etc.) may also cause galvanic corrosion.

1.4 Control of Facilities Deterioration. While coating of

surfaces is the most commonly used method of protecting them, it can be used most effectively in conjunction with other control methods. These include but are not limited to proper design of components, proper selection of materials and components, cathodic protection, controlling the environment, and use of corrosion inhibitors.

1.4.1 Corrosion Control by Coatings. Coatings protect metals

from corrosion by interfering with one or more of the conditions necessary for corrosion to occur. The three protective mechanisms of coatings are:

a) Barrier

b) Inhibitors

c) Cathodic protection

Regardless of the mechanism(s) of protection imparted by coatings, a multiple coat system is normally recommended for maximum protection of metals. The primer is formulated to bond well to the substrate and provide a good surface for adhesion of additional coats. Zinc or inhibitive primer pigments can provide corrosion control, as described above. Intermediate coats provide additional barrier protection and unite the primer and finish coats. The finish coat provides additional barrier protection as well as resistance to weathering, and color, texture, and gloss.

1.4.1.1 Barrier Protection. Most coatings provide corrosion

protection by forming a barrier that is relatively impermeable to moisture and electrolytes (usually salts) necessary for corrosion. No organic coating is completely impermeable, but some are much more so than others. Obviously, the coating film must be thick enough and free of discontinuities (holidays) to achieve maximum barrier protection.

1.4.1.2 Inhibitive Pigments. Some pigments are used in primers for metals to inhibit the corrosion reaction at the metal/primer interface. Red lead and zinc chromate pigments, used for this purpose for many years, are seldom used today because of health and environmental concerns. Acceptable alternate corrosion control pigments are available.

1.4.1.3 Cathodic Protection. Some coatings have a high loading of fine zinc particles to provide cathodic protection to steel surfaces. They convert anodic areas on the steel to cathodic areas. The zinc particles must be in electrical contact with each other and with the steel to provide this protection. The two basic types of zinc-rich coatings, organic and inorganic zinc, will be described later in this handbook.

A film of inorganic zinc silicate coating is unique because the film is relatively porous. Initially, the coating protects steel by cathodic protection, but its corrosion products gradually fill the porosity, so that it becomes a barrier coating. Should this barrier coat become scratched to expose the steel substrate, cathodic protection will begin again until the damage is healed. An inorganic zinc silicate coating is also unique in that it reacts with the steel to form a chemical bond.

Many organic coatings rely on physical rather than chemical bonding to steel.

1.5 Painting for Purposes Other Than Protection.

Facilities are often painted for other purposes than, or in addition to, protection. These include appearance, marking, and safety.

1.5.1 Cosmetic Appearance. Painting is an important factor

in promoting morale and productivity. NAVFAC P-309, Colors for Navy Shore Facilities, and Army TM5-807-7, Color for Buildings , present scientific approaches to the use of color to improve working and living environments.

FED-STD-595, Colors Used in Government Procurement, presents standard colors currently used by the Government. The colors are identified by five-digit numbers, and defined by fundamental color data. The standard, also available as a fandeck, includes reference chips of each color.

1.5.2 Marking Paints. Marking paints are used on airfield

runways, streets, and parking lots. Their chief function is to provide safety for personnel and equipment.

1.5.3 Safety Colors and Designs. Safety colors and designs

are used on military installations for rapid identification of hazards or safety equipment. They are also described in NAVFAC P-309.

1.5.4 Reflective Finishes. Reflective finishes on concrete

floors of hangars and shops may increase the lighting for workmen, particularly in sheltered areas such as under the wings of aircraft. Such smooth floors are easier to keep clean.

1.5.5 Nonskid Surfaces. Nonskid surfaces are frequently made

by adding grit to coatings on floors, ramps, and other walking surfaces to provide slip resistance.

1.5.6 Antifouling Coatings. Antifouling coatings prevent the

attachment and growth of marine fouling organisms by the controlled release of toxic materials.

Section 2: COATING COMPOSITIONS AND CURING MECHANISMS

2.1 Coating Composition. The primary ingredients used to

formulate coatings can be placed into one of three basic categories - solvent, resin, and pigment. Each of these categories has a special function in the formulation of coatings.

The resin (also called binder) and the solvent comprise the liquid portion, sometimes called the vehicle. Since the solvent evaporates as a coating cures, it is sometimes called the volatile vehicle, and the resin the nonvolatile vehicle. The resin and pigment which comprise the solid film after evaporation of the solvent are sometimes called the total solids or film solids.

Historically, the first paints utilized fish or vegetable (e.g., linseed) oils as binders and natural earth pigments. The first solvents were from trees (e.g., turpentine).

Now most resins and solvents are derived from petroleum, and many pigments are derived from organic synthesis or modification of natural minerals.

2.1.1 Solvent. Organic solvents are used to dissolve the

resin material and reduce the viscosity of the product to permit easier application. They also control leveling, drying, durability, and adhesion. Because the different organic polymers in different formulations vary greatly in their solubilities, some resins require much stronger solvents and/or greater amounts than others to dissolve them. In most water-based coatings, the water is a dispersing rather than a dissolving agent.

A blend of solvents is generally used in paint to achieve all the properties desired from them. The blend must completely dissolve the total binder system and be balanced to ensure compatibility and stability during all stages of curing.

Improper blends may result in cloudy films, pigment float to the wet film surface, or reduced film durability.

Paint solvents evaporate into the air and contribute to the production of photochemical smog. Thus, there is a great pressure to reformulate coatings to reduce the solvent content of paints.

2.1.2 Resin. Resins, also called binders, are the film-

forming portions of coatings. They are usually high molecular weight solid polymers (large molecules with repeating units) in the cured film. In some cases, lower molecular weight units in two liquid components react with each other upon mixing to polymerize into the higher molecular weight solid.

The resin is responsible for many of the properties of the coating. Thus, coatings are usually identified generically by the types of their resins. Important film properties related to the resin chemistry are:

a) Mechanism and time of curing

b) Performance in different environments

c) Performance on different substrates

d) Compatibility with other coatings

e) Flexibility and toughness

f) Weather resistance

g) Adhesion

h) Ease of topcoating and repair

i) Application properties (wetting, build, pot life, etc.)

2.1.3 Pigment. The pigment constitutes the solid portion of

a wet paint. Pigments are insoluble in the vehicle and are generally heavier than the liquid vehicle portion. They may settle to the bottom of a container upon prolonged standing.

Natural earth pigments are generally much more stable to light than synthetic organic pigments.

a) The pigment portion of coatings contributes to the following desirable properties:

(1) Opacity (hiding)

(2) Color

(3) Corrosion inhibition

(4) Weather resistance

(5) Moisture resistance

(6) Level of gloss and hardness

(7) Film build and reinforcement

b) The chief function of the pigment is to provide opacity (hiding) to obscure the substrate and protect the organic resin from degradation by the sun's ultraviolet light. Organic resins degrade to some extent in sunlight, some much more than others. Titanium dioxide is the pigment most frequently used to impart opacity to white paints and light tints, because it has high opacity. If a coat of paint does not completely obscure a surface, it is usually necessary to apply an additional coat.

c) Another important function of some pigments has already been mentioned - corrosion control. Inhibitive pigments can be very effective in reducing the corrosion that would otherwise occur. Lead and chromate inhibitive pigments were commonly used in paints in the past but are now restricted because of adverse health effects. Examples of lead- and chromate-containing pigments, and of those presently used, environmentally acceptable corrosion-inhibitive pigments are listed below:

Common Inhibitive Pigments

Relatively Hazardous Relatively Nonhazardous

Red Lead Zinc Oxide White Lead Zinc Phosphate Zinc Chromate Zinc Molybdate Strontium Chromate Calcium Borosilicate Basic Lead-Silico-Chromate Calcium Phosphosilicate

Zinc Phosphosilicate Barium Metaborate

d) Pigments also may improve adhesion and decrease moisture permeability. Leafing pigments such as aluminum tend to align themselves as parallel plates in the film to effectively increase film thickness by increasing the path that moisture must take to reach the substrate.

e) Other things being equal, the greater the resin-to-pigment ratio, the glossier will be the coating. The size of pigment particles (fineness of dispersion or grind) of the pigment in the vehicle also affects gloss. Other things being equal, the finer the dispersion, the glossier the cured film.

Secondary or filler pigments (talc, silica, etc.) are used to control viscosity, wet film build and leveling, and settling.

These cheaper pigments provide very little hiding. The pigment to resin ratio, generally expressed as pigment volume concentration (PVC), can vary widely. There can be no pigment, or the pigment content can approach a value called the critical pigment volume concentration (CPVC). As this point is approached, there is insufficient binder to wet the individual pigment particles and bond them to the substrate. This may result in a poorly bonded or porous film or one with a mottled appearance.

2.1.4 Other Components. There are also many additives used

in small amounts in coatings to provide some special function.

These include antifoam agents, flattening agents to reduce gloss, mildewcides, adhesion promoters, viscosity modifiers, and ultraviolet stabilizers.

2.1.5 Spreading Rate. If the percent solids by volume of a

coating is known, the dry film thickness of a coating can be determined from its wet film thickness by the relationship:

Dry Film Thickness = Wet Film Thickness x Percent Solids by Volume

Also, it can be shown mathematically that if 1 gallon of coating is uniformly applied to a flat surface at 1 mil (0.001 inch) wet film thickness, it will cover an area of 1600 square feet. Thus, if the percent solids by volume of a paint is provided by the supplier, its spreading rate at any dry film thickness (dft) can be determined, as shown below:

a) 0 Percent Solvent - 1600 square feet at 1-mil dft (100 Percent Solids) 800 square feet at 2-mil dft

400 square feet at 4-mil dft

b) 50 Percent Solvent - 600 square feet at 1-mil dft (50 Percent Solids) 400 square feet at 2-mil dft by volume 200 square feet at 4-mil dft

Obviously, this relationship is only true for coatings as received from the supplier without thinning. Thinning will reduce the percent solids by volume reported by the supplier and require calculating a new value before the above relationship can be used.

2.2 Mechanisms of Curing of Coatings. Coatings cure from

one of three basic ways:

a) Air oxidation (polymerization) of unsaturated drying oils

b) Evaporation of solvent from lacquers or water from emulsions

c) Chemical reaction of components or chemical reaction with water in air

Coatings that cure by solvent or water evaporation are unchanged chemically during curing. They are said to be thermoplastic, because they can be softened by heat or by solvent. Chemically curing coatings are said to be thermosetting, because they are not softened by heating or by solvent. Air-oxidizing coatings (oil-based paints) are thermoplastic after initial curing. Upon further curing (e.g., 6 months or more), the additional polymerization (cross-linking of polymers) slowly converts them to thermosetting coatings.

This is shown below:

Thermoplastic Coatings Thermosetting

Lacquers Chemically Reacting Products Latex Products Oil-Based Products (After Aging) Oil-Based Products (Initially)

2.2.1 Air Oxidation of Drying Oils. For coatings that cure

by air oxidation of drying oils (usually vegetable), oxygen from the air reacts with unsaturated fatty acids in their drying oils.

By this reaction, liquid resins are converted to solid films.

Metal driers are usually incorporated into formulations of drying oil coatings to accelerate their normally slow curing.

a) Examples of coatings that are cured by this mechanism are:

(1) Unmodified drying oils

(2) Alkyds

(3) Silicone alkyds

(4) Epoxy esters

(5) Oleoresinous phenolics

b) Such coatings wet surfaces very well and generally perform well in mild atmospheric environments, but they have limited durability in chemical environments, particularly alkaline environments. Epoxy esters provide some additional chemical resistance. They should not be confused with higher performance, two-component, chemically reacting epoxies.

Oleoresinous phenolic coatings are the only oil-based coatings that can be used successfully in water immersion service.

c) Formulating oil-based coatings with low-solvent content presents difficulties and requires major formulation changes from those used for high-solvent coatings. Thus, attempts are also being made to develop waterborne alkyd products.

2.2.2 Solvent of Water Evaporation. Coatings that cure by

simple evaporation of organic solvent are sometimes called lacquers. They are made by dissolving solid resins in an appropriate solvent. After application of a lacquer, the solvent evaporates to deposit the resin in a thin film. No chemical change occurs in the resin.

a) Examples of coatings that cure by this mechanism are:

(1) Shellacs

(2) Vinyls (polyvinyl chlorides)

(3) Chlorinated rubber

(4) Acrylics

(5) Bituminous coatings (coal tars and asphaltics)

b) Coatings of this type have poor solvent resistance, since they are deposited from a solvent, but are easy to topcoat and repair because the topcoat solvent bites into the undercoat to bond tightly. Because lacquers are high in solvent content, that is, volatile organic compounds (VOC), their use has been greatly curtailed.

c) Latex and many other waterborne coatings also cure by simple water evaporation. Emulsified particles of solid resin coalesce to form a film as the water is lost. These coatings usually contain some organic solvent to control curing and improve application properties. Latex films are quite flexible and tend to be more permeable than oil and alkyd films. Examples of latex coatings are:

(1) Acrylics

(2) Vinyls (polyvinyl acetates)

d) At this time, it is important to point out that there are other types of waterborne coatings that cure by mechanisms other than simple water evaporation. The three basic types of waterborne coatings are:

(1) Water soluble (of limited value)

(2) Water reducible

(3) Emulsions

e) Water soluble coatings are not durable enough for general use. The other two types of waterborne coatings find use on military facilities, although they may be somewhat less durable in some environments than corresponding solvent-based types. Water-reducible coatings contain a solvent blend that can be thinned with water. Alkyd and epoxy formulations are available in either water-reducible or emulsion forms. Such alkyd films are cured by air oxidation, and two-component epoxy films by chemical reaction.

2.2.3 Chemical Reaction. Coatings that cure by chemical

reaction are usually the most durable. They are generally packaged in two separate containers that are mixed to initiate the reaction. Components must be combined in the specified proportions in the manner specified by the supplier to achieve a film with optimum properties. Sometimes, an "induction period" is required after mixing and before application to permit the reaction to get started. After mixing, there is always a "pot life" during which the coating must be applied, before the reaction has advanced so far that the coating cannot be properly applied.

a) Examples of coatings that cure by chemical reaction are:

(1) Epoxies

(2) Coal tar epoxies

(3) Polyurethanes

(4) Polyesters

b) Because these coatings are thermosetting, they have excellent chemical and solvent resistance. They are difficult to topcoat when fully cured, because topcoat solvent cannot bite into the films. Thus, a topcoat is best applied while the undercoat still has some residual tack. If a completely cured thermosetting coating is to be topcoated, it is necessary to first spray a thin (e.g., 2 mil wet film thickness) tie coat (tack coat) of the topcoat and allow it to cure to a tacky state.

c) Another example of a chemically curing coating is an inorganic zinc coating. Different formulations may cure by different types of reaction. Usually the cure reaction involves the hydrolysis (reaction with water vapor from the atmosphere) of the silicate binder. Some cure by reaction with water from the air, and thus cure slowly in dry environments. A one-package water-based inorganic zinc coating cures by chemical reaction after evaporation of the water.

d) Zinc-rich organic coatings, on the other hand, cure by the mechanism of curing of their organic binders. Thus, zinc-rich epoxies cure by chemical reaction and zinc-rich vinyls, by solvent evaporation.

2.3 Properties of Different Generic Types of Coatings. The

properties of coatings commonly used on military facilities will be discussed individually below and then their properties will be summarized in a series of tables. Special mention will be made of the ease of formulating each generic type with a low VOC (solvent) content, since new restrictions on VOC content may limit or eliminate their use.

2.3.1 Alkyds and Other Oil-Containing Coatings. The

unmodified drying oil coatings initially developed were very easily applied, did not require a high level of surface preparation, and had good flexibility; they could readily expand and contract with the substrate. They did, however, have several drawbacks: they were slow to dry, had residual tack, and provided a limited period of protection.