Thompson’s WaterSeal

Yesterday, I had an interesting conversation with someone over at the Thompson’s WaterSeal company, owned by Sherwin Williams. I was calling because after trying to use their product to coat a neighbor’s fence, I found myself not able to use the product in the way the manufacturer recommended.

I have been told many things while getting advice at the hardware store and any advice I get I keep in mind that the person giving it to me is more-than-likely not an expert but might have some knowledge above what isle the product is in.

My questions included:

  • What type of sealer should I use to seal my deck or fence?
  • How can I apply that sealer quickly and thoroughly? Could I use a brush, roller, pump-up sprayer or a spray gun?
  • How often should I apply the sealer? Once a year? Every two years?
  • What could cause the sealer to degrade to the point that it would have to be redone?
  • Should I apply multiple coats or just one?

When shopping for sealers, I was told by the man in Home Depot that, based on his 30+ years of experience in the paint area, Thompson’s WaterSeal is not the best product. It has been around a while but it is the low-end consumer grade product. He said it would not last very long and putting it on in the fall is probably not the best time because the winter weather could be rough on it. He thought I might likely have to reapply it in the spring.

But, my neighbor who I am helping has an adjacent neighbor who already coated their fence using Thompson’s. So, that is what I was going to have to use for the project, to make it look the same. I bought two five gallon containers for the wood sealer.

In my call with Thompson’s, I was told that the wood sealer is totally oil-based and has UV protection so it will prevent the wood from turning grey. The other product, not in the green and white can, is a hybrid of oil and water and is better, for various reason, on concrete, stone and other similar surfaces.

One of the Home Depot store reps told me that I should go to the sprayer isle to look for the appropriate sprayer. One of the electric sprayers was rated for “sealers” so I purchased that one. It was about $90. Not too expensive if it could save me a few hours of work.

Then, while reading both the Thompson’s WaterSeal container and the electric sprayer instructions, there was a problem. The Thompson’s WaterSeal container did not specifically say if it was water or oil based. But, it did recommend applying using a pump-up sprayer. And, the electric sprayer, despite being rated for sealers and Thompson’s being one of the leading sealers on the market, was only to be used with “water-based” sealers. Neither of Thompson’s sealers at the Home Depot were water-based.

Therefore, I went back to the pump-up sprayer option with a back-brushing strategy. Apply the sealer with the sprayer and use a brush to spread it out is what I thought.

That didn’t work out. The thickness of the Thompson’s WaterSeal was too much for the sprayer. It came out clumpy and would not fan. Not only that but because it went on in a stream, when the stream hit the wood, a large amount of the liquid soaked into the wood causing a line of liquid, for lack of a better way of explaining it.

When doing my second project that day, I decided the sprayer was not going to be a good option. So, I used a brush to apply the sealer. It look about four hours to seal the deck vs. probably two hours if the sprayer had worked. The deck was recently powerwashed so it was clean and the boards were all similar. But, it was clear the following day that some areas were lighter than others and the areas around knots in the deck looked cloudy, for some reason.

After applying their product, I have the following questions?

  • Why did they recommend a pump-up sprayer when clearly it doesn’t work?
  • Why don’t they include whether the product is water or oil based on their packaging? Pretty basic stuff if you ask me.
  • Is there a way to dilute the product to a degree that would make it easier to spray on?
  • Is there a way to even out the look if the product goes on unevenly?
  • How can I fix the look of those areas, especially over the wood knots, that look hazy?
  • Why did the areas around the deck look cloudy?

In my call with Thompson’s, I was given the following answers. First, despite recommending a pump-up sprayer, the “recent batch” of the sealer was a bit thicker than previous batches so other customers were complaining that it was not working with pump-up sprayers. Second, the marketing department is responsible for putting information on the container and, for some reason, they did not put information about oil-based vs. water-based.

I was advised to skip the pump-up sprayer and revert back to applying their sealer with a roller or brush but even if applied with a brush I should use a backbrushing technique so that the sealer doesn’t sit on top of the wood but rather soaks into the wood.

When asked if I could put another thin coat on top to even out the look, I was told that would not be a good idea because the second coat would just sit on top of the first coat and could become sticky or “tacky” to the touch, much like tree sap on the outside of a tree I suppose. Their recommendation was to wait a few months, possibly until spring, and apply a thin second coat on top.

Finally, when I asked about the cloudiness on top of some areas, I was told that it could be because of moister that was in the wood prior to application of the sealer. Or, it could be that the sealer did not soak into the knotted areas. Either way, the only recommendation was to use some kind of degreaser or paint thinner sparingly to get rid of the haze and then wash it off immediately so it didn’t effect other areas of the deck.

I just told my neighbor that I will have to wait until I have enough time to use a brush to apply the sealer to the rest of her fence. I also contacted my customer about his deck and told him we should wait a few months to see if the color evens out and if he was unhappy with the cloudy areas he could use some Dawn dishsoap – an active degreaser – for about “one minute” per the Thompon’s rep recommendations, and if he wanted me to help with that I would stop over.

For now, I am going to stick to the slightly more expensive sealers. I do like the rich look of the Thompson’s product on new wood but on older wood or powerwashed wood, I definitely recommend a lighter water-based product that will last for 2-4 years and can be applied with either a pump-up sprayer or an electric sprayer.

I am surprised by how such a large well-funded company could have such basic communications issues about their product but that might be why Home Depot doesn’t sell Thompson’s products anymore. I get it now.

Stay safe and keep an eye out for future articles.

-Gary Pick