Stripping And Repainting Exterior Galvanized Metal Windows

Technical Procedures Disclaimer

Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.


We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.



A. This procedure includes guidance on removing paint build- up and repainting of all exterior galvanized metal windows to return them to operable condition. It also includes caulking all joints between metal elements and masonry where required.

B. Safety Precautions: All precautions shall be taken to prevent the possibility of fire in storage space and areas being painted.

  1. Provide adequate ventilation for removal of toxic fumes.
  2. Provide at least one 2B fire extinguisher for each 200 square feet of area occupied for paint storage and mixing.

C. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:

  1. Safety Precautions
  2. Historic Structures Precautions
  3. Submittals
  4. Quality Assurance
  5. Delivery, Storage and Handling
  6. Project/Site Conditions
  7. Sequencing and Scheduling
  8. General Protection (Surface and Surrounding) These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the Regional Historic Preservation Officer (RHPO).


A. Standards: National Association of Corrosion Engineers, 5.1.3 NACE No. 3 Commercial Blast Cleaned Surface Finish in "Visual Standards for Surfaces of New Steel Air-blast Cleaned and Sand Abrasive."


A. Packing and Shipping: Deliver materials to the site in the manufacturer's original containers with labels showing manufacturer, contents and color. Delivered material shall be identical to accepted literature and samples.

B. Storage and Protection: Store all materials in a single ventilated space. Storage space shall be kept neat and clean. Used rags, waste, and empty containers must be removed from the site at the end of each work day.


A. Environmental Requirements:

  1. The temperature of the surface to be painted and of the air in contact therewith shall be maintained at a minimum of 50 F and maximum of 95 F.
  2. No painting shall be done when relative humidity exceeds 85%.
  3. Surfaces to be painted shall be protected from dust and dirt during painting and finishing.



A. The Sherwin Williams Co.
101 Prospect Ave, N.W.
Cleveland, OH 44101

B. Devcon Corporation
30 Endicott Street
Danvers, MA 01923


A. Paint for Exterior Steel:

  1. Primer: One coat of zinc dust-zinc oxide primer such as "Galvanized Iron Primer," (Sherwin Williams), or approved equal; minimum 2 mil. D.F.T. (Dry Film Thickness) total.
  2. Finish Coats (2): Alkyd gloss such as "Matalastic II Enamel," (Sherwin Williams), or approved equal; minimum 4 mil. D.F.T. (Dry Film Thickness) total for both coats.

B. Colors:

  1. Primer: Make each coat clearly different in color.
  2. Base and Finish: Alkyd resin semi-gloss: Benjamin Moore or Sherwin Williams; make colors clearly different from each other and primer.
  3. Dry Film Thickness: Apply materials at not less than manufacturer's recommended spreading rate, to establish a total dry film thickness as indicated for each coat.
    • Primer: 2 mils.
    • Base and Finish Coats: 2 mils each.

C. Dry Grit Blasting: Fine grit No. 2-3 at 80-100 psi.

D. Backer Rod: Polyethylene compressible rod 50% larger in diameter than joint.

E. Sealant

  1. Multi-part, non-sag urethane sealant in conformance with ASTM C290, Type M, Grade NS, Class 25 light buff to match color of window paint.
  2. Joint primer recommended by the sealant manufacturer for specific applications and locations.

F. Fillers: Two-part epoxy metal filler, putty grade such as "Plastic Steel A" (Devcon Corporation), or approved equal.


A. Wire Brush: Non-ferrous metal brush, such as brass.



A. Protection: Enclose dry grit blasting work areas with temporary scaffolding or framework sufficient to support tarpaulin enclosure to prevent escape of abrasive. Shield adjacent masonry and glass with a temporary covering of cardboard or fiberboard held in place with heavy-duty strapping tape or wood bracing.

B. Surface Preparation:

  1. Determine that surfaces to which paint is to be applied are even, smooth, sound, clean, dry and free from defects affecting proper application. Contact the Contracting Officer after surfaces to be repainted have been cleaned and made smooth and before any paint is applied.
  2. Remove all paint, rust and scale from all steel surfaces, especially undersides and hidden locations by mechanical and manual methods as necessary. Do not remove or damage any of the galvanized surface. Stop abrasive blasting as soon as foreign matter and paint has been removed. The sash are to be restored to full operation.
  3. Paint removal may be done by dry grit blasting, scraping or sanding.
  4. Remove all window air conditioning units from windows.
  5. Remove all sealant between metal window frames and masonry.
  6. Clean the bare metal of all oily or greasy residue with a degreaser such as trichlorethylene available commercially in standard metal degreasers.
  7. Fill all small holes, depressions and cracks with metal filler following manufacturer's written directions. Finish all filled areas by sanding flush, after curing time has elapsed. Prime all metal within two hours of cleaning down to bare metal using a color obviously different from the finish color.


A. Apply paint in accordance with manufacturer's printed instructions.

B. Apply paint evenly and smoothly, free of runs, drips, sags, crawling, brush marks, holidays and clogging or angles. All paint coatings shall be brush or roller applied as appropriate to surface and finish.

C. Apply successive coats only when preceding coats are thoroughly dry and hard. Sand between coats to produce even and smooth surfaces.

D. Apply additional coats when undercoats, stains, or other conditions show through final coat of paint, until pain film is of uniform finish, color and appearance. Ensure that corners, edges, crevices and exposed fasteners receive a dry film thickness equal to that of flat surfaces.

E. Meeting lines between colors shall be straight and sharply defined with no blending, running or gaps.

F. Adjacent materials shall be fully protected by drop cloths or other suitable coverings. Paint drips, splatters, etc., shall be removed immediately.

G. Each coat of paint is to be slightly darker than the preceding coat with the final coat exactly matching the accepted samples.