Thompson’s WaterSeal Finish Review

Thompson's WaterSeal

Thompson's WaterSeal

Thompson’s® WaterSeal® Waterproofer Plus Clear Wood Protector is designed for all exterior wood and decking surfaces. This protection includes: Water repellency, prevents water damage, maintains natural wood grain, all while resiting mold growth. Thompson’s® WaterSeal® claim to fame is the ability to waterproof your exterior wood.

We tested the Thompson’s® WaterSeal® in the Clear finish.

Thompson’s® WaterSeal® Scores (1-10)

Appearance After Initial Stain Application: 8

- The Thompson’s® WaterSeal® Clear did not alter or change the appearance of the wood. After full drying we tested the ability to repel water. Water did bead on top of the finish and did not absorb into the wood.

Preventing UV Graying at 2 Year Mark: 1

- As far as we can tell, Thompson’s® WaterSeal® does not prevent UV graying at all. This is a huge disappointment as preventing UV graying is the number one reason to stain your exterior wood and decking.

Wear/Tear and Peeling: 8

- Thompson’s® WaterSeal® penetrates deep into the wood. There was no peeling or wearing. We would have given it a 10 if  the product still repelled water but it did not.

Cost Per Square Foot: 9

- Thompson’s® WaterSeal® is a very inexpensive product to purchase and coverage is exceptional. Unfortunately the saying “you get what your pay for” applies here as the Thompson’s® WaterSeal® offers no UV protection whatsoever.

Preventing Mold/Mildew/Algae: 1

- After 2 years the entire deck was covered in black mold. It seems that the oils used in Thompson’s® WaterSeal® feed and promotes the growth of mold spores.

Ease of Application: 9

- Since this is a clear product, Thompson’s® WaterSeal® applies extremely easy without the need to back wipe. Just apply with a pump sprayer or stain pad. This finish does not show overlap marks.

Color Shifting (darkening) after 2 Years: 7

- We would say that the Thompson’s® darkens in color since there was a good amount of mold growing in the finish.

Difficulty of Reapplication: 6

- A heavy cleaning would be needed to remove all the graying and mold from the surface.

Overall Score Thompson’s® WaterSeal® at 2 Year Period: 6.125

- Overall Thompson’s® WaterSeal® Clear Plus wood finish is a “clear” disappointment. Any finish that offers zero ability to prevent UV graying should not be considered for your deck or exterior wood.

Product Information:

Cost: $19.99 per Gallon
Stain Type: Clear Water Repellent
Available Colors: Clear
Application Temperature: 45-95 F
Coats Required: 1 coat for most scenarios
Coverage Per Gallon: 200-300 Square Feet
Application Tools: Sprayer, Pad, Brush, Roller
Dry Time: 48 Hours
Cleanup: Mineral Spirits
VOC Compliant: 250 Compliant in all States
More Info: Product Data
Manufacturer: Thompson’s

Test Deck Stats:

Location of Deck: North Carolina
When Tested: May 2007
Deck Wood Type: Teak Decking
Deck Square Footage: 400 Square feet
UV Exposure: Full sun
How Many Years Tested: 2 Years
Stain Color Used:

*All products tested and results are from our experience. We offer no guarantee of similar results. Take inconsideration that results may differ due to different wood types, exposure to UV radiation, and natural weathering.

33 Responses to “Thompson’s WaterSeal Finish Review”

  1. Mike says:

    I'm shocked at your results. I used this product on my deck and fence and it took 3-4 years for them both to start graying and they are both in full sun.

    • Mike, A clear sealer with no tint such as Thompson\’s water seal offers no UV protection. It is not possible for it to last 3-4 years. This is a known fact in the industry.

      • Peak2Creek says:


        I need to agree with the above post. Before applying Thompson's to your deck there are a few things you should consider. Firstly you are committing to the product until the deck rots off or you invest in a lot of chemical and mechanical cleaning. While there is a fair bit of debate as the Thompson's content the reality is that by its very nature the product sinks into the pours of your deck and keeps any stain applied later from penetrating which is essential for protecting your investment.

        If you have already applied the product you are looking at using a stain and paint stripper. A neutralizer. A 3 Rinse process and a serious amount of sanding with 60 or 80 grit sandpaper.

        All stains require a minimal colourant load to provide any protection from UV.

        As a 4th generation paint distributor I can assure you that you would be better never to go down that road.

        Talk to an independent paint dealer and follow there advice. Preparation is the key to success with any stain product so follow the instructions and you will have years of worry free enjoyment.

  2. Mike says:

    It's not only possible, it's true. This was my experience and that's a fact. You siue sound biased against Thompson's.

  3. Mike, the Thompson's we tested was clear and had no color, pigment or trans oxides. The only way to protect from graying is to have UV absorbers such as trans or iron oxides. It is an impossibility to have UV protection without this or something similar.

    They do offer the Thompson's in some colors. Those would offer UV protection but the clear is not capable of it.

  4. Patricia says:

    Doesn't this product say it allows the wood to grey naturally? Some people like that look

    • Patricia, yes the Thompsons will gray and oxidize. If that is the look you desire then I would consider the TWP in clear as it is a registered wood preservative by the EPA. It will protect your wood from rotting and mold better then Thompsons clear.

  5. christine says:

    waterbased k320 from benjamin moore is clear and will protect from uv rays without colour, also F076 clear penetrating oil finish will do a good job on well prepared wood, best sandpaper by the way is 80 grit as recommended by BMoore

    • Deck Stain Help says:

      Christine, Do you have personal experience with the k320 from BM where you could post a picture in to forum? I would like to see a picture of it after a year on a deck.

  6. Kevin in WI says:

    I have used Thompson's water seal with good results in the past. It appears they changed their formulation as when I applied it last year (2012) it didn't really soak in at all. The protection it offered from water was a joke. The first couple of times it rained, water beaded for a few minutes and then just soaked right in.

    I have a large deck and the cost of treating it wasn't small. The time, more so. It was a complete waste of money and time. I wouldn't waste either on this product ever again.

    • SHIRLEY MARLKE says:


      • Peter says:

        The new mix of Thompsons water seal does not work. After 6 months it had faded in colour. After 8 months water protection ceased. After 1 year most had started to peal off. Total garbage. Since it does not penetrate the wood you should be able to strip it off with a power washer. I'm about to do so on my deck. I have ordered Armstrong Clark stain to replace it. Best of luck. P.S. it should have gotten a wear/tear peeling rating of 2!

  7. Billie says:

    I was going to use this pn my mothers porch posts made put of pine. They have the product wood iron on them (put on about 30 yrs ago and then about a yr ago we put on a mixture of linseed oil and turpintine). She wants to water proof them as they are starting to get mold on the bottom portion and they do need protection from weather and snow etc. i am surprised to read your review! Any other suggestions? We bought the wood iron in Co. 30 yrs ago but it is not avail. Where she is at and also is very very expensive and I am not even sure it would waterproof anyway.

  8. BHD says:

    Do NOT expect to apply it with a garden pump sprayer = impossible even with large aperture nozzle. Thompsons claim of "Easiest application with garden sprayer" is a selling point (that sold me), that is NOT to be believed. A ladder brush/roller is near impossible to use on mountainous terrain (log home), so my job remains undone – Thompson's cost me time and money. I wondering how they will respond to my letter? Are you listening/reading Thompson's?

    • JRM says:

      Got to agree BHD this is not the same product I used 2 years ago. It's viscosity is 10 fold as to what it used to be. I to am at a standstill on my project. After 5 different pump sprayers, I'm going to have to give in to a brush and roller. To Thompsons, wake up, remove the old comment from the label. This is a new formulation and impossible to pump spray. Do the test yourself and if you find/ produce a sprayer that works, advertise it on the label. My time is more valuable than committing to product loyalty. After this year struggling with the new formula I will find a comparable product and move on.

  9. Rjm says:

    Bad product

  10. kandif says:

    I used Thompsons water seal on my wooden swing set before it was put together four days ago and when rub it i still get a oily finger. I am just wondering if it is safe to put up and why is this still happening after four days.

  11. Linda says:

    I used this product by appying it with a new pump sprayer. The spray was not coming out in a fine mist, so I think too much product was applied. Now after 2 days it doesn't seem to be drying very well. I tried to even it out with a paint brush. How long should it take to dry.
    Thank you.

    • JcSwantko says:

      Linda – alot depends on temperature, and humidity levels. I've applied in high temp high humidity and it took forever for the "tackiness" to subside. An earlier poster mentioned pump sprayers not being effective. I couldn't agree more. I've had the best luck with paint pads.

    • Steve says:

      Mine never dried. Rather, it kept a thick wax like film for one month. I then applied a deck stripper and light power wash. The thick wax became a thin wax layer. Two weeks later, I applied another deck stripper and power washed. The wax film has thinned but still exists. I regret using Thompson's on beautiful cedar wood. At some point, I may simply replace the wood. A costly mistake as a result of using a bad product, Thompson's.

  12. Steve says:

    Bar none, the worst product I have ever purchased. After application on beautiful red cedar wood, there was a wax film that covered the deck. It was slippery when dry, worse when wet, and felt as though someone had dripped wax candles for days on the deck. A decks stripper and light power wash was recommended, after which the wax film was lessened but still existed. My goal now is to strip the sealer again, brush it off and power wash it again. If the film is not removed, I will remove what was once beautiful wood and start over. A costly mistake. I have never blogged regarding a product but this was the worst purchasing decision I have ever made.

  13. Michael Moore says:

    I've used this product many times with good results–today the results were terrible. Have they changed the formula, did my 6 gallons get too hot or cold? I'll never use this product again. I've always used a garden sprayer with good results, today it wouldn't soak in, left white droplets (gazebo and spraying overhead, lattice-work and railing) that wouldn't dry or soak in.

  14. TedC says:

    The can illustrated in your article is Thompson's WaterSeal "Plus Clear Wood Protector." That product has a noticeable yellow tint, no doubt due to a UV-blocking dye. Your test results suggest that you may have tested the original WaterSeal, which is indeed colorless.

  15. TomH says:

    Unfortunately, I believe they have changed their formula… The new stuff I just bought went on milky white, puddled terribly and had to be wiped down (the entire deck). I checked with others, I've been told that's the way the new stuff is. I had to wipe the entire deck with a rag to get coverage and clean up the milky white junk… I've used Thompsons for years..but never again.

  16. deckowner1 says:

    For any users of Thompsons water seal who are desparately trying to get the stuff off your deck so that you can apply another product, I have found the solution. We put Thompsons on our new deck this past spring. After only 3 months, the boards began to gray – terrible UV protection. We bought the Thompsons deck stripper, which would not completely remove the product, which contains parafin oils and heavy hydrocarbons that penetrate the wood. After much searching I FOUND THE SOLUTION! It is a degreaser specially formulated for removing hydrocarbons. It is called EC 1800 and is sold by EcoChem.
    I used this product to completely remove all Thompsons water seal from deck and was left with beautifully cleaned bare wood to which I could apply a different water sealer. If the Thompsons product is not completely removed, you cannot apply a different sealer. It will not penetrate due to the oils from the Thompsons product that are soaked into the wood.

    EC 1800 is completely natural and biodegradable. Worked like a charm!

    • GregL says:

      Thank you for this information! Unfortunately, the company has not responded to my email or voice mail messages. Did you dilute the degreaser? If so, what ratio did you use? I notice that the sell this stuff by the liter, do you know how much area a liter will be able to clean? My deck is approximately 250 sq. ft..

      Thank you again.

  17. Dan says:

    We are putting in medium sized cedar deck in Toronto, Canada in the Spring. I just want to protect it from the elements. We don't care about the grey color at all. Which is the best clear water sealer on the market then? I understand that clear sealers don't protect from UV. I want the least amount of maintenance on Cedar as possible. Due to budget we have to stay with the Cedar building material.

    • Dan, best clear that we have ever used is the Defy Extreme Clear.

      • Dan says:

        Thanks. What about Penofin products? I can get them easier here in Canada. I am just not that into mold. I don't mined something that is easy to apply a few times a year.

        • Penofin does not make a true clear and in our tests, it has a tendency to turn black after a year or two. What brands can you get locally?

          • Dan says:

            Sikkens & Penofin — The Big Box stuff like Thompsons, Cabot, Olympic, BM. Behr, Sherwin Williams. Our deck contractor is not a fan of staining b/c of the maintenance. He is old school and suggested applying Thompsons twice a year. Thanks again!

          • Dan says:

            After extensive research on this topic I think we are going to install IPE for the deck floor. We always wanted it anyway. Apparently prices have come down a bit to make it more affordable. At least for the floor boards.

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