FAQs

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 pretreated 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® 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.

 

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

Beading alone is not a measure of water repellency. It is just a surface phenomenon - remember, water will even bead up on a dirt field when it starts to rain. Some products are formulated to produce water beading on wood but do not effectively protect the wood from water penetration and damage. The best way to tell if a surface is waterproofed is to use the “Splash Test.” Pour a little water on the surface. If it darkens, the water is penetrating and the surface needs to be protected. If it beads, rolls off or stands on the surface, but does not darken the surface, it is protected. Thompson’s® WaterSeal® Waterproofers and Exterior Stains penetrate the wood so that even after the beading is gone, the waterproofing protection lasts.

Q: If a product is labeled “waterproofer”, does that automatically mean it will protect against water damage?

Passing federal or industry tests IS NOT required for a product to be advertised and sold as a “waterproofer.” However, nearly all Thompson’s® WaterSeal® products exceed the widely accepted industry tests which measure the amount of water repellency a waterproofing product provides (these tests are developed by industry leaders and the American Society of Testing and Materials [ASTM]). On tests with a pass/fail standard, a score of 60% or higher means the product passes. There are many products on the market which do not meet this criteria yet still claim to be waterproofers.

Q: What surface preparation should be done prior to staining?

One very important step is to remove all existing loose, flaking or peeling stain. Failure to do so will result in continued flaking and peeling. Other preparation steps include cleaning the surface thoroughly. Apply to a small sample section of the surface to ensure the color you want.

Q: What is the difference between a clear, transparent, semi-transparent, and solid stain?

Clear Provides long-lasting protection while helping enhance and maintain wood's natural color
Transparent Provides complete outdoor wood protection by adding subtle color
Semi-Transparent Adds beautiful color while still allowing some wood grain to be seen
Solid Hides the wood grain while allowing wood texture to show

Q: How long does Thompson’s® WaterSeal® Waterproofing Stain take to dry?

Drying time will vary depending on temperature and humidity. Under normal conditions, the product should dry to the touch within 2 hours.

Q: How do I know if my deck needs waterproofing?

Perform the “Splash Test”. Sprinkle water on various sections of the surface to be sealed. If the water absorbs and darkens the color of the substrate within five seconds, surface is porous and considered ready to be treated.

 

Q: Will Thompson’s® WaterSeal® Clear Multi-Surface Waterproofer impart color to my deck, concrete, or brick surface?

No. Thompson’s® WaterSeal® Clear Multi-Surface Waterproofer applies white but dries clear and allows your wood to gray naturally over time. Prior to covering the entire surface, a test patch should be done in an inconspicuous place. The test patch will give you an indication as to whether you will like the look of a clear product.

Q: How do I know if my surface needs waterproofing?

Simply perform the “Splash Test”. Sprinkle water on various sections of the surface to be sealed. If the water absorbs and darkens the color of the substrate within five seconds, the surface is porous and ready to be treated. If the water beads up or otherwise sits on top of the surface, then it does not need protection at this time.

Q: I applied Thompson’s® WaterSeal® Clear Multi-Surface Waterproofer and it has not dried. What happened?

“More is not better”. The situation that you have described is an over-application of Thompson’s® WaterSeal® Clear Multi-Surface Waterproofer. The “excess” is due to the fact that Thompson’s® WaterSeal® Clear Multi-Surface Waterproofer was unable to penetrate into the substrate. Because of this, you need to make sure that the surface is completely dry and free of debris prior to applying. If over-application occurs and there is puddling of the product, redistribute product within 15 minutes to a dry area or wipe off.

Q: Will the formula of Thompson’s® WaterSeal® Sport Seal® or Fabric Seal change the feel of the treated surface?

No. These products will not change the surface’s feel or leave it sticky.

Q: What fabrics can be treated with Thompson’s® WaterSeal® Sport Seal®?

Thompson’s® WaterSeal® Sport Seal® can be used on many different fabrics, including canvas, nylon, polyester, cotton, and flannel. It also enhances the water repellency of performance fabrics and factory-applied treatments.

Q: What fabrics can be treated with Thompson’s® WaterSeal® Fabric Seal?

Thompson’s® WaterSeal® Fabric Seal can be used on many different fabrics, including canvas, nylon, polyester, and cotton.

Q: Does Thompson’s® WaterSeal® Fabric Seal resist color fading?

Yes. In addition to providing maximum strength waterproofing protection, Thompson’s® WaterSeal® Fabric Seal also contains UV inhibitors in order to resist color fading caused by the sun.

 

Q: How do I know which type of cleaner to use for my wood before applying a clear waterproofer or exterior stain?

It’s important to choose the right cleaner for your project to ensure the best adhesion during the waterproofing / staining process. Use the below guide as a reference when selecting a surface cleaning product.

For Exterior Wood Surfaces:
If you need to remove: Use:
Stains from dirt, mildew, algae & fungus and there is little or no trace of a residual finish Thompson's® Water Seal® Deck Wash
Weathered clear waterproofers & transparent or semi-transparent stains in addition to stains from dirt, mildew, algae & fungus Thompson's® Water Seal® Heavy Duty Deck Cleaner
Oil & water-based solid stains and long-lasting, hard-to-remove semi-transparent stains & waterproofers in addition to stains from dirt, mildew, algae & fungus Thompson's® Water Seal® Maximum Strength Deck Stripper
On REDWOOD/ CEDAR/ HIGH EXTRACTIVE Wood: Tannin staining and restore lighter color of Redwood Cedar, Mahogany or other highly extractive wood species in addition to removing stains from dirt, mildew, algae & fungus and/or, as instructed to neutralize any wood species after using other cleaners
Thompson's® Water Seal® 3 in 1™Wood Cleaner
For Exterior Multi-Surfaces:
If you need to remove: Use:
On exterior surfaces such as wood & composite decks, fences, concrete & masonry, outdoor furniture, roofs & siding: Stains from dirt, mildew, algae & fungus with a non-bleach, chlorine-free oxygenated foaming formula Thompson’s® WaterSeal® Oxy Foaming Action Exterior Multi-Surface Cleaner

Q: How important is it to properly clean my deck before applying a clear waterproofer or exterior stain?

Proper surface preparation is necessary for the best waterproofing / staining application and performance. All exterior wood – from decks to fences to siding – should be cleaned before sealing, staining, or painting to remove waterproofers, wood stains, or stains from dirt, mildew, or algae. Even new wood can have dirt or other invisible barriers to the penetration of a coating. For instance, new wood can have invisible mill glaze, caused when the heat of the milling equipment reacts with the natural oils in the wood, that needs to be removed.

Q: What is the best way to apply Thompson’s® WaterSeal® cleaners?

The fastest way to apply is with a pump-up sprayer (using a coarse setting), but you can also apply with a brush or a roller. You should apply liberally. In the case of areas with heavy discoloration or dirt, apply a second coat, brush lightly with a broom and hose off.

Q: How long after cleaning can I apply waterproofers or stains?

Weather and environment can create various factors. Always follow the instructions on the waterproofer or exterior stain product label.