ITEM 411 – PAINT

411.1 Description

This Item shall consist of furnishing and applying all paint materials including vehicles, pigments, pastes, driers, thinners and mixed paints for steel and wooden structures; sampling testing and packing; preparation of the surface and application of paint to structures.

411.2 Materials Requirements

411.2.1 General

Paint, except aluminum paint, shall consist of pigments of the required fineness and composition ground to the desired consistency in linseed oil in a suitable grinding machine, to which shall be added additional oil, thinner and drier as required.

Aluminum paint shall consist of aluminum powder or paste of the required fineness and composition to which shall be added the specified amount of vehicle.

The paint shall be furnished for use in ready mixed, paste or powder form.

All paints shall meet the following general requirements:

1. The paint shall show no excessive settling and shall easily redisperse with a paddle to a smooth, homogeneous state. The paint shall show no curdling, livering, caking or color separation and shall be free from lumps and skins.

2. The paint as received shall brush easily, possess good leveling properties and shall show no running or sagging when applied to a smooth vertical surface.

3. The paint shall dry to a smooth uniform finish, free from roughness grit, unevenness and other imperfections.

4. The paint shall not skin within 48 hours in a ¾ filled tightly closed container.

411.2.2

The paint shall conform to the requirements of the Specifications indicatedas follows:

Ready Mixed Red Lead Paint Aluminum Paint White & Tinted Ready Mixed Paint Foliage Green Bridge Paint Black Paint for Bridges And Timber Structures Basic Lead-Silico-Chromate Ready Mixed Primer Ready Mixed Aluminum Paint

AASHTO M 72 and PNSType I, II, III & IV AASHTO M 69 and PNSType I & II AASHTO M 70 AASHTO M 67 AASHTO M 68 AASHTO M 229 AASHTO M 260 and PNS

411.2.3 Drier

This Specification covers both straight oil drier (material free from resins and gums), and Japan drier (material containing varnish gums). The drier shall be composed of lead manganese or cobalt or a mixture of any of these elements, combined with a suitable fatty oil, with or without resins or gums, and mineral spirits or turpentine, or a mixture of these solvents. The drier shall conform to the following requirements:

1. Appearance – Free from sediment and suspended matter.

2. Flash Point – (Tag Close Up) Not less than 30⁰C.

3. Elasticity – The drier when flowed on metal and baked for 2 hours at 100 ⁰C shall have an elastic film.

4. Drying – It shall mix with pure raw linseed oil in the proportion of 1volume of drier to 19 volume of oil without curdling and the resulting mixture when flowed on glass shall dry in not more than 18 hours.

5. Color – When mixed with pure, raw linseed oil in the proportion of 1volume of drier to 8 volume of oil, the resulting mixture shall be darker than a solution of 6 grams of Potassium Dichromate in 13 cc of pure Sulfuric Acid (sp.gr. 1.84).

411.3 Construction Requirements

411.3.1 Proportion of Mixing

It is the intent of this Specification to provide a paint of proper brushing consistency, which will not run, steak or sag and which will have satisfactory drying qualities.

411.3.2 Aluminum Paint, Field Coats on Structural Steel

The paint shall be mixed in the proportion of 240 grams of aluminum powder or paste per liter of vehicle of long oil spar varnish. This makes a paint containing 21 percent pigment and 79 percent vehicle. The weighed amount of powder or paste shall be placed in a suitable mixing container and the measured volume of vehicle poured over it. The paste or powder shall be incorporated in the paint by vigorous stirring with a paddle. The powder or paste will readily disperse in the vehicle. Before removing any paint from the container, the paint shall be thoroughly stirred to insure a uniform mixture, and the paint shall be suitably stirred during use. The paint shall be mixed on the job and only enough for one day’s use shall be mixed at one time.

When two field coats of aluminum paint are specified, the first coat shall be tinted with lampblack paste or Prussian blue paste in the quantity of 24 grams/liter of paint. The exact quantity used shall be sufficient to give a contrast in color which can be readily distinguished. When three field coats of aluminum paint are specified, the second coat shall be tinted.

411.3.3 Aluminum Paint, Field Coats on Creosoted Timber

The paint shall be mixed as specified for Aluminum Paint for Structural Steel except that the proportions shall be 270 grams of aluminum powder or paste to one liter of vehicle.

Other paint composition may be used when and as stipulated in the Special Provisions.

411.3.4 Containers and Markings

All paints shall be shipped to strong substantial containers plainly marked with the weight, color and volume in liters of the paint content, a true statement of the percentage composition of the pigment, the proportions of the pigment to vehicle, the name and address of the manufacturers, and the stencil of the authorized inspecting agency. Any package or container not so marked will not be accepted for use.

411.3.5 Sampling and Testing

Method of sampling shall be as follows:

1. One 20-litre can sample in original unopened container shall be obtained for 100 cans of the delivered material or 10% fraction thereof.

2. One 4-litre can sample in original unopened container shall be obtained for every 100 cans or fraction thereof of the delivered material.

Methods of testing will be in accordance with the applicable AASHTO or ASTM Methods.

411.3.6 Painting

411.3.6.1

The painting of structure shall include the proper preparation of the surface; the application, protection and drying of the paint coatings, the protection of the pedestrians, vehicular or other traffic upon or underneath the structures, the protection of all parts of the structure (both superstructure and substructure)against disfigurement by spatters, splashes and smirches of paint or of paint materials; and the supplying of all tools, tackle, scaffolding labor, paint and materials necessary for the entire work.

Paint shall not be applied during rain, storms or when the air is misty, or when, in the opinion of the Engineer, conditions are otherwise unsatisfactory for the work. Paint shall not be applied upon damp surfaces or upon metal which has absorbed heat sufficient to cause the paint to blister and produce a pervious paint film.

No wide flat brush shall be used. All brushes preferably shall be either round or oval but if flat brushes are used, they shall not exceed 100 mm in width.

The paint when applied shall be so manipulated as to produce a uniform even coating in close contact with the surface being painted, and shall be worked into all corners and crevices.

On surfaces inaccessible to brushes, the paint shall be applied by spray gun or with sheepskin daubers specially constructed for the purposes.

Paint shall be thoroughly stirred, preferably by means of mechanical mixers, before being removed from the containers, and, to keep the pigments in suspension, shall be kept stirred while being applied.

When a paint gun is used, the equipment used shall be of an approved type and shall have provision for agitation of paint in the spray container. In the case of aluminum paint, the pressure used shall be only that necessary to secure adequate atomization. If in the opinion of the Engineer unsatisfactory results are obtained from the use of a spray gun, its use shall be discontinued and the painting completed by the use of brushes.

411.3.6.2 Painting Structural Steel

Surfaces of metals to be painted shall be thoroughly cleaned of rust, loose mill, scale, dirt, oil or grease, and other foreign substances. Unless cleaning is to be done by sandblasting, all weld areas, before cleaning is begun, shall be neutralized with a proper chemical, after which they shall be thoroughly rinsed with water. Cleaning may be by any of the following three methods:

1. Hand Cleaning

The removal of rust, scale and dirt shall be done by the use of metal brushes, scrapers, chisels, hammers or other effective means. Oil and grease shall be removed by the use of gasoline or benzene. Bristle or wood fiber brushes shall be used for removing loose dust.

2. Sandblasting

Sandblasting shall remove all scale and other substances down to the base metal. Special attention shall be given to the cleaning of corners and re-entrant angels. Before painting, sand adhering to the steel in corners and elsewhere shall be removed. The cleaning shall be approved by the Engineer prior to any painting. The material shall be painted before the rust forms and not later than 2 hours after cleaning.

3. Flame Cleaning

Oil and grease shall be removed by washing with suitable solvent. Excess solvent shall be wiped from the work before proceeding with subsequent operation. The surface to be painted shall be cleaned and dehydrated (freed of occluded moisture) by the passage of oxyacetylene flames which have an oxygen to acetylene of at least one. The inner cones of these flames shall have a ratio length to port diameter of at least 8 and shall not be more than 4 mm center to center. The oxyacetylene flames shall be traversed over the surface of the steel in such manner and at such speed that the surface is dehydrated, and dirt, rust, loose scale, scale in the form of blisters or scabs, and similar foreign matter are freed by the rapid intense heating by the flames. The flames shall not be traversed so slowly that loose scale or other foreign matter is fused to the surface of the steel. The number, arrangement and manipulation of the flames shall be such that all parts of the surface are adequately cleaned and dehydrated. Promptly after the application of the flames, the surface of the steel shall be wire-brushed, hand scraped wherever necessary and then swept and dusted to remove all free materials and foreign particles. Compressed air shall not be used for this operation. Paint shall be applied promptly after the steel has been cleaned and while the temperature of the steel is still above that of the surrounding atmosphere, so that there will be no recondensation of moisture on the cleaned surfaces.

4. Shop Painting of Structural Steel

When all fabrication work is completed and has been tentatively accepted, all surfaces not painted before assembling shall be given two coats of Red Lead Shop Paint conforming to the requirements of this Specification. (The inside of top chords for trusses and laced members or inaccessible parts, except contact surfaces, may be painted before assembling). Shipping pieces shall not be located for shipment until thoroughly dry. No painting shall be done after loading the materials on transport vehicles.

Erection marks for field identifications of members shall be painted upon previously painted surfaces.

With the exception of abutting joints and base plates, machine-finished surface shall be coated, as soon as practicable after acceptance with a hot mixture of white lead and tallow before removal from the shop. The composition used for coating machine-finished surface shall be mixed in the following proportions:

Pure Tallow Pure White Lead Pure Linseed Oil

1,915 grams 958 grams 1.0 liter

5. Field Painting of Structural Steel

When the erection work is complete including riveting and straightening of bent metal; all adhering rust, scale, dirt, grease or other foreign material shall be removed as specified under cleaning of surfaces.

As soon as the Engineer has examined and approved all field rivets, the heads of such rivets and field bolts, all welds and any surfaces from which the shop coat of paint has become worn off or has otherwise become defective, shall be cleaned and thoroughly covered with one coat of shop coat paint.

When the paint applied for “touching up” rivet heads and abraded surfaces has become thoroughly dry, such field coats as called for shall be applied. In no case shall a succeeding coat be applied until the previous coat has dried throughout the full thickness of the film. All small cracks and cavities which were not sealed in water-tight mannerly the first field coat shall be filled with a pasty mixture of red lead and linseed oil before the second field coat is applied.

The following provisions shall apply to the application of all field coats. To secure a maximum coating on edges of plates or shapes, rivet heads and other parts subjected to special wear and attack, these parts shall first be stripped, followed immediately by the general painting of the whole surface, including the edges and rivet heads.

The application of the final coats shall be deferred until adjoining concrete work has been placed and finished. If concreting operations have damaged that paint, the surface shall be recleaned and repainted.

411.3.6.3 Painting and Timber Structures

Timber structures shown on the Plans to be painted, shall be given two coats of the specified materials, which shall be thoroughly brushed in. Additional coats shall be required when so specified on the Plans. All surfaces shall be thoroughly dry before painting, and each coat shall be allowed to stand for three or four days, or until thoroughly dry before applying the succeeding coat.

Timber which required painting must be seasoned timber surfaced on 4sides. It shall be either untreated or salt-treated timber as specified on the Plans.

The entire surface of all untreated timber that is to be painted, shall be given a priming coat immediately after the material is delivered to the project. All contact surfaces shall receive the second coat paint.

Special care shall be taken during construction and handling so that the pieces to be painted do not come in contact, except when required, with the creosoted materials and that no oil is brushed on the same during construction operations. The Contractor shall be required to pile such pieces separately from the creosoted materials and keep them from contact with same until ready for erection.

Creosoted materials such as guardrails and guide posts which are to be painted, shall be painted with aluminum paint as specified above.

411.3.6.4 Painting Galvanized Surface

For the purpose of conditioning the surface of galvanized surfaces to be painted, the painting shall be deferred as long as possible in order that the surface may weather.

Before painting galvanized surfaces they shall be treated as follows:

1. In 4 liters of soft water, dissolve 60 ml of copper chloride, copper nitrate, and sal ammonia, then add 60 ml of commercial muriatic acid. This should be done in earthenware or glass vessel, never in tin or other metal receptacle. Apply the solution with a wide flat brush to the galvanized surface, when it will assume a dark almost black color which on drying becomes a grayish film.

2. The surfaces, when dry, may then be painted as described.

411.3.6.5 Repainting Existing Structures

When called for on the Plans or in the Special Provisions, existing structures shall be given the number and kind of coats of field paint as stipulated. The surface to be repainted shall be cleaned as specified under Subsection 411.3.6.2, Painting Structural Steel, with the added provisions that all dead or loose paint shall be removed by scraping, chipping, or brushing as may be necessary. Timber railings, name plates, planking and other interfering parts shall be removed before cleaning is begun and shall be replaced after the painting has been completed and the last coat has thoroughly dried. The application of the coat shall be as specified under Subsection 411.3.6.2, (5), Field Painting of Structural Steel.

411.4 Measurement and Payment

Painting shall not be measured and paid for separately, but the cost thereof shall be considered as included in the contract unit price of the items where called for.