We had a home built about five years ago. Our deck is constructed with
pressure treated wood and while it is under a roofed area, it has south
exposure and gets quite a bit of sun. Our builder did a couple of things
that appear to have paid off:
1) Suggested we not treat it with anything for at least six months. He
wanted to let the moisture bleed out of wood via exposure to sunlight before
2) He gently steered us away from Thompson's. He admitted it was partly an
appearance thing, but he preferred Olympic Water Guard. He also thought
Olympic had more staying power. He said to plan on washing and retreating
about every other year. However, based on your comment you might not want
to use Olympic because it does add an amber tone to the wood.
We followed his advice and are pleased. At the end of six months the deck
had sun bleached slightly. I cleaned and sprayed two coats of Olympic which
gave it a slightly amber look. Both of my subsequent retreatments were
preceeded with a light pressure wash using deck cleaner. These subsequent
treatments were done with a brush (one coat), which I believe does a better
job than spray. Again, the deck will retain a golden brown appearance which
you might find objectionable.
By comparison, I built a deck at a previous residence and used Thompson's.
I can't say that Thompson's provided a bad finish but it added absolutely no
color to the wood. It was like brushing water on - at times it was
difficult to tell where you had treated. We sold the house before we could
see how it aged. As far as cost goes, they are both in the same ballpark.
I belive Thompson's has been running a "5th quart free" sale for the past
3-4 years - Still talking about $12-14 dollars for a 5 quart can.