TECHNICAL BULLETIN
Many people take great pride in owning an older home, but older homes can require a great deal of maintenance to keep them at their best.
One of the best ways to keep an older home looking fresh while accenting its character is coating with a top quality exterior paint. This will not only beautify your home but will also help preserve it, since paint is also the first line of defense against the harsh elements that can weather a home’s exterior.
Here are some answers to some common questions from the owners of older homes.
Question: What type of paint provides the most durable protection for old wood?
Answer: It depends upon the type of surface to be painted and its condition. With a sound substrate that has been properly prepared (scraped, sanded, cleaned, and primed), two coats of acrylic latex paint such as Diamond Vogel Palisade Ultra Premium Exterior Acrylic Latex, and Durango Acrylic Latex Exterior Finish, or EverCryl Exterior Acrylic Latex Finish will provide the best adhesion and, consequently, maximum durability.
Question: Can latex paint be applied over oil-based paint?
Answer: Yes, today’s acrylic latex paints are formulated to provide excellent adhesion to surfaces painted with oil or alkyd based paints. But, if you encounter a surface with more than three or four coats of oil paint, you may want to apply an oil base. Before applying either an oil or latex paint, be sure to prepare the surface by removing any dirt, grime, chalk, or other contaminants. Glossy surfaces should be sanded to provide a good surface for the new paint to adhere to.
Question: Can you tell whether the old paint is oil-based or latex?
Answer: Remove a piece of the old paint with a scraper, place it between your fingers, and apply pressure. If the paint snaps in half or breaks into pieces, it’s probably an oil-based paint. If it is flexible enough to bend between your fingers, then it is most likely a latex product. Depending on how old the paint is, latex paints may not be flexible enough to bend between your fingers, so it may be hard to tell in some cases.
Question: What is the best way to remove oil-based paint from old exterior wood?
Answer: Some professional painting contractors use a torch or heat gun along with a scraper. The use of sanders or grinders may also be used, being careful not to be too aggressive. Sandblasting may also be an option, being careful not to be too aggressive and tear up or go all the way through the wood. Chemical strippers may also be used. Since these methods can be dangerous if proper safety practices are not followed, the hiring of a professional should be considered. Old oil-based paint may contain lead, so extra caution should be taken with removal and disposal, and be sure to dispose of the old paint according to your local regulations.
Question: When is it necessary to strip old paint down to bare wood before painting?
Answer: If the substrate has three or four coats of oil-based paint and you want to use a acrylic latex, then the old paint should be removed. You could, however, add an extra coat of oil-based paint without removing the earlier coats. If the old paint is latex or if there are only a couple coats of oil-based paint, you can use a quality acrylic latex paint without removing the old paint, assuming that the surface is clean and stable.