knots on cedar wood

Hey guys,

This message is going out to all deck people who have coated cedar decks. If the deck has knots they usually turn white in less than a year. I know its not the fault of the sealer its just the wood. But, anyway I usually thin down a coat of my sealer and spot prime the knots and then apply the sealer over the entire deck. A painter that has been around for years told me to use paint thinner on the knots before applying the sealer and the thinner will glue the knot together so the sealer will last longer. any suggestions? When I talk about sealers I'm talking about F&P and Super deck -not solid colored stains Thanks
Hi Tom,
The reason you have problems with knots is because knots in wood are around 70% resin. Have you ever noticed that when a piece of wood or a tree rots, the knots are always the last thing to go. Some sealant manufactures use the resin from these knots for their base. Expensive, but good.
Sense these knots have so much resin in them, it is very hard to get them to accept any penatrating finish. You really have to back brush to get the finish to penatrate.
When you apply a surface coating over knots, oil/water base, it will not make a solid bond due to the resins. They will, over time lose any bond they have and you will get the whitesh look your talking about.
I belive that if you strip this deck and use a good penatrating oil finish and back brush, you can solve the problem.
Hope this helps.

Jim Bilyeu
Exterior Woodcare
Hey Tom
We use Ready Seal on all our decks, When we do cedar decks we add mineral sprits(Paint thinner) to the sealer it helps the knots absorb the sealer deeper and tends to look better and last longer, Chris@ sunbrite

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