How to Stain or Paint Cedar Siding
Cedar siding has a great reputation as a wood that works well with a wide range of finishes. It can be stained or painted and will provide many years of good service. It is highly resistant to cracking when exposed to weather extremes as long as the surface has been properly coated. However, there are several problems that can cause discoloration.
Dirt is not usually much of a problem. It can be removed with a mild detergent and gently scrubbing with a soft brush. Rinse thoroughly with a garden host to remove the detergent.
Mildew is a common cause of discoloration on cedar siding. In fact, it can cause problems on just about any type of surface. Trying to cover mildew with stain or paint will not work. When it is time to refinish cedar siding, remove the mildew with a good quality mildew remover.
Extractives bleed is usually caused by moisture getting behind the siding. Cedar contains naturally occurring extractive chemicals that provide weather resistance and durability. If moisture gets behind the siding, it can dissolve these chemicals and deposit them when running down the surface. To prevent these types of stains, moisture problems must be eliminated. Try to locate the area where water is getting behind the siding and seal the entry point. Don’t allow the sealing material to get on the surface of the wood because that in itself will cause discoloration. Mild staining might be washed away by rain over a period of several weeks. A commercial cleaner can be used in difficult cases.
Water stains often occur in combination with extractive bleed and mildew. These stains can be difficult to remove. Scrubbing the wood with an oxalic acid solution might work. Be careful with oxalic acid solution. Follow the manufacturer’s instructions regarding safe handling.
Chalking is caused by deterioration of paint. It occurs when a paint film deteriorates and releases particles that look like fine powder. The only cure is to refinish the siding.
Before you refinish cedar siding, take time with surface preparation. The surface condition can substantially affect the performance of both stain and paint. Careful preparation will definitely extend the life of the coating.
New Cedar Siding
New cedar siding has to be protected from the weather. Don’t leave the siding exposed to the elements, but get the finish on as soon as possible. It is usually not necessary to perform extensive surface preparation as long as the siding has not weathered for more than two weeks and is clean and dry. However, dirt, oil, and other foreign substances must be removed to ensure good stain penetration.
For smooth, flat-grained cedar, some surface preparation may be needed. The surface should be lightly scuffed with 50-60 grit sandpaper. This will greatly increase the performance of the finish and will not detract from a smooth look. Surface preparation is not necessary for textured cedar.
Weathered Cedar Siding
Weathered siding that has been exposed to the elements for longer than 2 weeks may have a degraded surface that is unsuitable for staining or painting. Prepare the surface by sanding, brushing, and washing before applying the finish.
Paint Finishes for Cedar Siding
Paint must be removed if the old surface is severely peeled, blistered, or if checking (small cracks) are present. Paint removal is also necessary if a penetrating stain or water-repellent finish is to be applied.
Changing from a painted surface to a wood stain can be quite difficult. Paint usually penetrates the surface by a slight amount, and this can prevent the absorption of stain. The end result will look blotchy and in some cases, the stain will not penetrate at all. If the surface is currently painted, it’s best to stay with paint instead of trying to switch to stain.
Finishes can be removed by sanding, wet sandblasting, pressurized water spray, electrically heated paint removers and chemicals. Although quick and easy, sandblasting and pressurized water spray are not recommended unless extreme care is taken to avoid damage to the wood’s surface. The high pressure can easily remove sections of the surface and ruin the siding. If the old paint is lead-based, it can be quite hazardous to remove and special procedures must be taken. In this case, it is best to hire a contractor that specializes in lead paint removal to do the job.
Weathered Water-Repellent Finishes for Cedar Siding
Weathered water-repellent preservative finishes should be cleaned with a new bristle brush to remove loose fibers and dirt. If the surface is soiled, it may be scrubbed with a mild detergent solution. The surface should be thoroughly rinsed and allowed to dry completely before refinishing. If mildew is present, use a product that is specifically designed for the purpose. Be careful - Never mix bleach with any product that contains ammonia as the fumes can be harmful or fatal.
Weathered Penetrating Cedar Siding Stains
Weathered penetrating stains are relatively easy to refinish. Excessive scraping or sanding is not required. A stiff, new bristle brush may be used to remove surface dirt, dust and loose wood fibers before applying the stain.
Last year I purchased a cedar board and batten house built in 1967, which needs to be restained. We are using a natural stain and tested it on sample boards and it was fine. However, when it was applied to full siding boards, we see “milking” or “luminesence”. Is our only option to paint the cedar or can the underlying sealer or whatever is causing this problem be removed? The house was power washed with water before we started. Thank you so much for your help. Alene Shaull
Alene,
When stain turns a milky color, it almost always indicates moisture contamination. This is usually caused by applying stain before the siding has completely dried.
Since you pressure-washed the cedar, that’s likely the cause. Pressure washing can drive water deep into the cedar. Even when the surface appears dry, there can still be moisture present inside the wood. After stain is applied and heat from the sun warms the siding, the trapped moisture will migrate to the surface and cause discoloration of the stain.
This can be a difficult problem to solve. The first thing to try is nothing - let the siding dry (hopefully) on its own by releaseing the moisture naturally. This can take a long time because the stain will slow the process.
After several months pass, you can try cleaning a small test area of the discolored siding with a nylon bristled hand brush and oxygen bleach. Oxygen bleach is available at most home improvement centers and is much safer to use than regular chlorine bleach. Don’t rub too hard - let the oxygen bleach do the work. Rinse with a garden hose and let dry thoroughly. Then try to stain the test area and see how it looks.
If this fails, you can move to either a semi-transparent or solid stain. This of course will hide the look of the wood. Painting over a previously stained surface is extremely difficult and best left to professionals.
Thanks for the interesting article. I love reading about home improvement!