Without the proper protection from the elements your exterior wood will warp, bow, cup, split and just rot. This will result in hundreds if not thousands of dollars in wood replacement. Your deck is an extension of your home and a great place to enjoy and entertain.
Let's look at cleaning methods. You have wood that is greyed or black from mildew and now you want to restore your wood. Some so called professionals use a pressure washer alone to clean this off the wood surface. By itself the pressure washer is not a good choice. Even though you have cleaned the surface, mold and mildew spores remain in the wood fibers and when you apply a sealer over the top of these spores you will have mold or mildew growth under the finish and eventually causing the finish to fail.
Some professionals use bleach. Even some stain manufacturers tell you to use bleach or make a cleaner based on bleach as the main ingredient. This will work and it will kill the mold or mildew but at a price. The wood will end up being lighter than the original wood because it bleaches out the natural color of the wood. This will cause your stain to have a different look than you intended. Bleach is also used in the process of manufacturing paper to help break up the wood fibers. Why would you use this on a deck or fence?
Well what should my wood restoration professional use to clean my deck?
You can use various store bought cleaners but here are some guidelines. For stripping an old finish, the cleaner used should be a sodium hydroxide based cleaner. Fair warning this can cause chemical burns and kill vegetation. If you have wood with no previous sealer then you would use a sodium percarbonate based cleaner which is much easier on the wood. Both of the cleaners need to be followed up with an application of either citric acid or oxalic acid to neutralize the cleaners and restore the natural PH levels of the wood.
Using bleach leaves the PH levels extremely high and thus the wood surface will not accept the stain as readily as it would have normally.
One last thing, for best results let your wood weather for 6 months before applying any stain or sealer. It is not required but you will get better results and the finish will last longer thus saving you money.
Stay tuned for future posts where we discuss our stain choices and why we use them.