Thompson’s WaterSeal Advanced Performance Trial

While it’s certainly understandable and possible to preserve the look of new wood, there are specific things you need to do to make it happen.

lumber_thompsons_watersealWeathering, mold and foot traffic all conspire to discolour your new deck, and the process usually takes less than one season to get started. If you want to retain that new wood look, you need to fight against the forces of discolouration using a two-part process: water repellent application to keep wood looking bright as long as possible; then a deck brightener to restore the new-wood look when the inevitable discolouration eventually sets in.

Thompson’s is the long-standing favourite in the water repellent category because they invented the stuff back in 1929. That’s when Edward Addis Thompson, a polymer chemist, developed a liquid to prevent water absorption in masonry. Water repellents have also been used successfully on wooden decks for almost 30 years, though they typically need to be reapplied each year.

Thompson’s WaterSeal Advanced natural wood protector is unusual in that it claims a two-year working lifespan. That’s good news if it’s true, and I’m testing right now with wood samples I’ve coated and placed outdoors in full sun. I’m using white pine because it shows discolouration most obviously.

  • one board has been sanded with an 80-grit abrasive before application of Thompson’s on half the surface, with the other half left bare;
  • the other board was prepared with unsanded wood

So far my tests with WaterSeal Advanced are looking good. I’ll keep you posted on the results.

One thing you need to know about WaterSeal Advanced is that more product is not better. Definitely not better. In fact, it’s essential to apply only one, thin coat to the wood, and even then, make sure the liquid is fully spread out. You can apply it with a pump-up sprayer, but the surface still needs to be physically brushed to even out the application. A pad-type applicator performs very well for working the product into the surface. Heavy coats or multiple coats will remain sticky and probably promote peeling. WaterSeal Advanced can also be applied to pressure treated wood immediately after new construction. The product works best after the application of mill glaze remover, to maximize the absorbency of the wood surface.

All water repellents eventually stop working, and deck brighteners are effective for restoring a light wood colour. The results are not exactly the same as new lumber, since deck brighteners bleach out some of the variation in wood grain colours, but they still do work surprisingly well just the same. Roll on a deck cleaner/brightener, pressure wash it off, give the wood a quick sanding if surface fuzziness has formed, then keep the new look with a water repellent.