Some Useful Q&A on Exterior House Painting with Cedar Siding
A customer recently asked these questions about the staining process on the cedar siding on exterior of his home.
- Will stain penetrate the existing paint cover on the cedar siding? A customer rep. at a local paint supplier was of the opinion that the stain would not penetrate the paint, but it would adhere to and cover it.
- If that’s the case, what steps would be taken to ensure that the stain does adhere to the painted surfaces?
- Would the bare wood areas be treated in a way that the painted and then stained areas would not show delineations between the two areas? That is, will the two distinct areas blend into each other?
PAINT vs. STAIN ON CEDAR SURFACES
Solid Color Acrylic Stain can be applied over existing surfaces previously painted. We have been doing it for years with very positive results especially on cedar. Cedar is a very porous wood and tends to fracture and crack in dry climates. Acrylic paint is an open pored or vapor permeable product, meaning that the house can breathe through the coating. Paint has a tendency to fail and peel off of cedar even with a primer underneath as paint is a grabbing product and not really a penetrating product. Stain is designed to penetrate into porous surfaces and is a better overall product on a substrates like cedar. A lot of the primers used under paint on cedar do not penetrate adequately or better than a good quality stain either. When you add the weight of a paint to another painted surface, it can actually pull the currently intact paint away from the substrate(the Cedar Board) which is another concern with paint on Cedar. Maintenance painting is typically needed for structures where owner’s insisted on using paint. When we perform maintenance to many of these buildings we have to use stain and not paint to achieve much better results.
Stain to cedar is typically back rolled on the 1st coat to assist with the penetration to the siding and seal porosity and then a second coat is applied. Due to the porous nature of cedar this really should be done with even paint.
SANDING IRREGULAR EDGES AFTER SCRAPING
Once an area is scraped to an adjacent area where the paint is not peeling, there is most often an irregular edge or a delineated edge as you say. The mission is to ensure that no loose coating or all peeled away areas are attended to and then the coating is applied and locks down that irregular edge. Sanding is very difficult through multiple layers of paint and most often will not remove an irregular edge. As a protective liquid, all coatings conform to the surface they are presented. The mission of scraping or sanding is not to create a perfectly smooth surface, but to ensure the removal of loose, peeling paint. Spackling over irregular areas is not recommended as spackle or wood putty does not move with temperature and will most often crack and break out. In addition, you cannot re-create a grain with spackle or wood putty and it will most often blemish or flash through the coating applied over the top.