Alligatoring and Wrinkling

Cause

Alligatoring and wrinkling is caused by excessive buildup of paint. Eventually, multiple cracking of the paint film occurs as seasonal temperature variations inhibit expansion and contraction of the paint film with the substrate. Simultaneous to cracking, the inability of the thick paint film to expand and contract with the substrate results in adhesion loss. Paint applied to this surface will invariably accelerate flaking of the total film down to the substrate.

Wrinkling is caused by applying paint in excess of the recommended wet film thickness and by applying paint containing strong solvents to already dry paint films. These solvents cause the underlying paint film to dissolve and expanded (wrinkle) under the newly applied paint. The result is a wrinkled finish.

Solution

Wrinkled surfaces can be power-sanded to a smooth surface. Surfaces that show alligatoring or cracking must have the paint stripped to the bare wood by power sanding, use of paint remover, or heating gun and scraper.

Bare wood that has been exposed to weathering must be sanded to fresh wood. Exposure of sanded fresh wood to sunlight for more than a one-week period will result in peeling of the newly applied paint.

Recommended Sherwin-Williams Coating System

Prime bare wood with the A-100 Exterior Latex or Acrylic Wood Primer

Two coats of Exterior Latex House and Trim Paint

Cause

Algae are green chlorophyll-containing organisms that obtain their nutrition by photosynthesis. Like mildew, algae will flourish where there is an adequate source of moisture. It grows almost exclusively outdoors. Cement-based products are more prone than other substrates to support algae growth.

Solution

Provide drainage to rid immediate area of excess ground moisture. Locate and correct source of moisture that is saturating vertical surfaces. Remove algae growth with a soft brush and household bleach. Flush area with clean water and allow to dry thoroughly. Remove loose paint to a sound surface. Sand weathered wood to fresh wood.

Recommended Sherwin-Williams Coating System

One coat A-100 Alkyd exterior wood primer

Two coats Exterior Latex House and Trim paint

Blistering/Peeling

Cause

Moisture

Poor surface preparation by failing to remove chalk residue

Factory primer on new substrate is hard, glossy, or contaminated.

Application of latex paint below minimum application temperature.

Solution

Remove loose paint with pressurized water.

Scrape areas that are loose but resist removal by water blasting.

Eliminate moisture by determining the need for:

a. Caulking- cracks, holes, and seams

b. Wedge vents

c. Attic louvers

d. Exhaust fans

Scrape off paint from problem area and then sand to fresh wood, feathering edges.

Recommended Sherwin-Williams Coating System

Prime bare wood with Sherwin-Williams A-100 Latex or Alkyd Exterior Wood Primer.

Apply two coats of Sherwin-Williams topcoat, preferably latex.

Chalking

Cause

Slight chalking of a weathered paint film is normal and desirable. Application of new paint over severe chalk will cause peeling problems.

Aluminum siding can develop an excessively thick coat and will require power washing to insure complete chalk removal.

Solution

Remove chalk by washing siding with detergent and water. If some chalk remains after first washing, then wash again for complete removal. Rinse well with clear water. Allow to dry thoroughly.

Recommended Sherwin-Williams Coating System

-Aluminum siding (flat or smooth)

Two coats Exterior Latex House and Trim Paint (Flat or Satin only)

-Aluminum siding (embossed)