**Minnesota Construction Specification 82---Painting Metalwork**

**1. Scope**

The work consists of cleaning metal surfaces and applying paints and
protective coatings.

**2. Paint**

For the purpose of this specification, paints and coatings shall be
designated by types as defined below.

Materials for systems requiring two or more coats shall be supplied by
the same manufacturer.

Unless otherwise specified and before application, the contractor shall
furnish in writing to the engineer for approval a plan outlining
procedures proposed for painting metalwork and a list of material
including name of manufacturer, pertinent product identification names
and numbers, and product data sheets. Data shall reflect the
requirements set forth in this section.

*Type 1 - Alkyd primer**. ***Alkyd based, rust inhibitive primer shall
be lead and chromate free. Primer shall have a minimum of 54 percent
solids, by volume. Color availability shall be red, gray, and white.
Primer shall be able to be applied satisfactory at 2 to 3 mils dry-film
thickness in one coat.

*Type 2 - Alkyd enamel (gloss).* Alkyd based enamel shall be lead free.
It shall have a minimum of 49 percent solids, by volume. Alkyd enamel
shall be able to be applied satisfactory at 2 to 3 mils dry-film
thickness in one coat. Finish shall be gloss.

*Type 3 - Alkyd enamel (semigloss).* Alkyd based enamel shall be lead
free. It shall have a minimum of 55 percent solids, by volume. Alkyd
enamel shall be able to be applied satisfactory at 2 to 3 mils dry-film
thickness in one coat. Finish shall be semigloss.

*Type 4 - Epoxy polyamide primer.* Epoxy polyamide primer shall be lead
and chromate free. It shall have a minimum of 56 percent solids, by
volume. Epoxy primer shall be able to be applied satisfactory at 4 to 6
mils dry-film thickness in one coat. Color availability shall be red,
gray, and white. Epoxy primer shall conform to AWWA Standard C 210 and
AWWA Standard D 102.

*Type 5 - Epoxy polyamide (intermediate or finish).* Epoxy polyamide
shall be lead free. It shall have a minimum of 56 percent solids, by
volume. Epoxy polyamide shall be able to be applied satisfactory at 4 to
6 mils dry-film thickness in one coat. Finish shall be semigloss. Epoxy
finish shall conform to AWWA C 210 and AWWA D 102.

*Type 6 - Acrylic polyurethane (gloss).* Acrylic polyurethane shall be
lead free. It shall have a minimum of 74 percent solids, by volume.
Polyurethane shall be able to be applied satisfactory at 3 to 5 mils
dry-film thickness in one coat. Finish shall be gloss.

*Type 7 - Acrylic polyurethane (semigloss).* Acrylic polyurethane shall
be lead free. It shall have a minimum of 58 percent solids, by volume.
Polyurethane shall be able to be applied satisfactory at 3 to 5 mils
dry-film thickness in one coat. Finish shall be semigloss.

*Type 8 - Vinyl acid wash treatment.* Pretreatment primer for galvanized
and nonferrous metal. Pretreatment primer shall have a minimum of 8
percent solids, by volume. The applied dry-film thickness of
pretreatment primer shall not exceed 0.5 mil. Steel primed with
pretreatment primer shall be topcoated within 6 to 8 hours in humid
conditions.

*Type 9 - Single package moisture cured urethane primer.* Urethane
primer shall have a minimum of 50 percent solids, by volume. Primer
shall be able to be applied satisfactory at 2 to 3 mils dry-film
thickness in one coat. Color shall be metallic aluminum.

*Type 10 - Coal tar epoxy.* Coal tar epoxy shall have a minimum of 75
percent solids, by volume, and conform to the requirements of NRCS
Material Specification 583 Coal Tar Epoxy Paint (Steel Structures Paint
Council PS No. 16, Type I). Coal tar epoxy shall be able to be applied
satisfactory at 8 to 15 mils dry-film thickness in one coat.

**3. Tinting**

Tinting shall not be performed in the field unless otherwise specified.

**4. Surface preparation**

Surfaces to be painted shall be thoroughly cleaned before the
application of paint or coatings. Surface preparations required by this
specification are as designated by SSPC (Steel Structures Painting
Council) and are summarized by the methods listed in this section.

***Method 1---***Near white blast (SSPC-SP10). All surfaces to be coated
shall be prepared by removing all grease and oil using steam cleaning or
solvent cleaning methods per method 5. After degreasing is completed,
sand or grit blasting shall be performed to remove all dirt, rust, mill
scale, and other foreign material or residue. The cleaned, finished
surface shall be a minimum of 95 percent free of all visible foreign
material or residue.

***Method 2---***Commercial blast (SSPC-SP6). All surfaces to be coated
shall be prepared by removing all grease and oil using steam cleaning or
solvent cleaning methods per method 5. After degreasing is completed,
sand or grit blasting shall be performed to remove all dirt, rust, mill
scale, or other foreign material or residue. The cleaned, finished
surface shall be a minimum of 67 percent free of all visible foreign
material or residue.

***Method 3---***Bush-off blast cleaning (SSPC-SP7). All surfaces to be
coated shall be prepared by removing all grease and oil using steam
cleaning or solvent cleaning methods per method 5. After degreasing is
completed, sand or grit blasting shall be performed to remove dirt,
rust, mill scale, or other foreign material or residue. Mill scale,
rust, and paint are considered tightly adherent if they cannot be
removed by lifting with a dull putty knife.

***Method 4---***Hand tool cleaning (SSPC-SP2). All surfaces to be
coated shall be prepared by removing all oil or grease using steam
cleaning or solvent cleaning methods per method 5. After degreasing is
completed, nonpower handtools shall be used to remove loose, detrimental
foreign material. Adherent mill scale, rust, and paint need not be
removed.

***Method 5---***Solvent cleaning (SSPC-SP1). Surfaces to be coated
shall be prepared by removing all visible oil, grease, soil, drawing and
cutting compounds, and other soluble contaminants from surfaces with
solvents or commercial cleaners using various methods of cleaning, such
as wiping, dipping, steam cleaning, or vapor degreasing.

**5. Paint systems**

For the purposes of this specification, systems of painting and coating
metalwork are designated as defined in this section.

*Paint system A**---***Consists of the application of one primer coat of
type 1 and two or more coats of type 2 (gloss) or type 3 (semigloss) to
provide a minimum dry-film thickness of 6 mils.

*Paint system B**---***Consists of the application of one primer coat of
type 9 and two or more coats of type 2 (gloss) or type 3 (semigloss) to
provide a minimum dry-film thickness of 6 mils.

*Paint system C**---***Consists of the application of one coat of type 4
and one or more coats of type 5 to provide a minimum dry-film thickness
of 8 mils.

*Paint system D**---***Consists of the application of one coat of type 4
primer, one coat of type 5, and one coat of type 6 (gloss) or type 7
(semigloss) to provide a minimum dry-film thickness of 11 mils.

*Paint system E**---***Consists of the application of one coat of type 9
and one coat of type 6 (gloss) or type 7 (semigloss) to provide a
minimum dry-film thickness of 5 mils.

*Paint system F**---***Consists of the application of two coats of type
10 at a dry-film thickness of 8 mils. per coat. Total system shall
provide a minimum dry-film thickness of 16 mils.

*Paint system G**---***Consists of the application of two coats of type
4 and two coats of type 9 paint. Total system shall provide a minimum
dry-film thickness of 14 mils.

**6. Application of paint**

Surfaces shall be painted immediately after preparation or within the
same day as prepared with a minimum of one coat of the primer type
specified. Remaining surfaces not required to be painted shall be
protected against contamination and damage during the cleaning and
painting operation.

Paints shall be thoroughly mixed immediately before application.

After erection or installation of the metalwork, all damage to
shop-applied coating shall be repaired and all bolts, nuts, welds, and
field rivet heads shall be cleaned and painted with one coat of the
specified priming paint.

Initial priming coats shall be applied by brush except on surfaces
accessible only to spray equipment. All other coats may be applied by
brush or spray. Each coat shall be applied in such a manner to produce a
paint film of uniform thickness with a rate of coverage within the
guidelines and limits recommended by the paint manufacturer and as
outlined in section 2 of this specification.

The drying time between coats shall be as prescribed by the paint
manufacturer, but not less than that required for the paint film to
thoroughly dry. The elapsed time between coats in paint system F shall
not exceed 24 hours. If for any reason the critical recoat time is
exceeded, the coated surface shall be treated with the manufacturer\'s
recommended tackifier solvent or brush blasted to roughen the surface.

The finished surface of each coat shall be free from runs, drops,
ridges, laps, or excessive brushmarks and shall present no variation in
color, texture, and finish. The surface of each dried coat shall be
cleaned as necessary before application of the next coat.

**7. Atmospheric conditions**

Paint application shall not be performed when the temperature of the
item to be painted or the surrounding air is less than 50 degrees
Fahrenheit. Painting shall be performed only when the humidity and
temperature of the surrounding air and the temperature of the metal
surfaces are such that evaporation rather than condensation results
during the time required for application and drying. The surface shall
be dry and a minimum of 5 degrees Fahrenheit above the dew point.
Surfaces protected from adverse atmospheric conditions by special cover,
heating, or ventilation shall remain so protected until the paint is
thoroughly dry.

**8. Tests**

Dry-film thickness on ferrous metal shall be determined by the use of a
nondestructive magnetic instrument, such as an Elcometer or Mikrotest
gauge. Instruments shall have been calibrated within 1 month before use.
Film thickness on nonferrous metal shall be determined with film gauges
during the application process. Systems with film thickness less than
specified shall be brought into conformance by the application of one or
more additional coats of the specified material.

**9. Construction details**