General

Q: Do I really need to clean my surface before I waterproof or stain or can I simply hose it down with water?

In order to get maximum penetration and performance of the waterproofer or stain, it is important that the surface is cleaned of any stains from mildew, dust, dirt, oil, soot, grease or other contaminants. The Thompson’s® WaterSeal® cleaner line has a product for every exterior wood cleaning need.

Q: Does pressure-treated lumber really need waterproofing protection?

Yes. Although pressure-treated lumber is pre-treated with chemicals, preventing insect damage, it is NOT waterproofed. In fact, the chemical treatment actually causes the lumber to dry out quicker and absorb more water than untreated lumber. When wood absorbs water, it swells; as the wood dries it shrinks. These wet/dry cycles cause wood to crack, warp and split.

Q: Are all waterproofers basically the same?

No. There are standardized industry tests developed and adopted by both the Federal government and the American Society of Testing and Materials (ASTM) which measure the amount of water repellency a waterproofing product provides. Products for wood must be greater than 60% efficient at providing water repellency in order to meet the minimum water repellency criteria. Not all products provide this much protection, but nearly all Thompson’s® WaterSeal® products exceed this standard.

Q: Is there a difference between stain and paint?

Yes. Stains are formulated to better penetrate wood and accentuate its natural beauty. With paint, you have a choice in the level of sheen you want while stains generally have a flat sheen. With stain, you also have a choice in the level of opactiy. Transparent shows the most wood grain while adding subtle color. Semi-transparent allows some of the wood grain to be visible to the eye. Solid covers the grain, but still allows some of the wood’s natural texture to show through. Paint covers the grain.

Q: Do I need to apply a clear waterproofer over my stain?

Not with Thompson’s® WaterSeal® exterior stains. They are specially formulated so you get unsurpassed waterproofing protection and beautiful color at the same time. However, not all stains provide the same level of water repellency. If you are not using Thompson’s® WaterSeal® exterior stains, we can’t guarantee how much waterproofing protection you’re getting.

Q: Does water beading prove that a surface is waterproofed – protected from water damage?

No. To determine if your surface is still protected perform the splash test. Sprinkle water on various sections of the surface to be sealed. If water absorbs and darkens color of surface within five seconds, surface is porous and considered ready to be treated. If water beads up or otherwise sits on top of surface, then the surface does not need protection at this time.