Dock Preservative
 

New dock with pressure treated pine is almost a year old and am thinking of putting on a stain/preservative. WoodRX looks very interesting and wonder if anyone has experience with this product.

Probably not legal for use over water. Stain the dock when it is out of the water for the winter.

Cuprinol
 

I used the above brand name with great luck. Pine docks are 30+ years old. Prior to that my dad uses Creosote coated wood that have lasts 50+ years.

Creosote are banned currently, and Cuprinol can only be applied when the dock is out of the water. Cuprinol is a solid green stain so not to many people care for the color, it does an excellent job preserving the wood!

If the dock is pressure treated why are you worried about treating it?

My docks and decks have always been pressure treated... every few years they get pressured washed, and if a board starts to splinter, it gets replaced... After that the pressure treatment, guarantees the longevity... I watch people use additional preservative all the time, and well yes there decks look a bit more fancy because of it... In the end I have many neighbors who have ended up replace newer decks then mine, while mine is still going strong....

You definitely don't want to stain pressure treated wood--it's already absorbed as much as it can. Just a waste of time/money, and not good for the environment.

Disagree with this. When the wood is treated it certainly is very wet with preservative hence why it very heavy. But it doesnt stay that way, it dries out like any other wood. When demoing mine the weight of the wood is not much different than untreated. The preservative doesnt keep it from drying. This is why you are instructed to not stain it for maybe 6 months. While it does dry out the preservative stays in though. I have done both with my decks and just replaced mine 3 years ago. I wont stain this one at all because it seems to only last one season. I'll live with the grey color but you certainly can stain pt and has nothing to do with having "already absorbed as much as it can".

Thanks for the various responses and opinions.

First of all, look at the www.woodrx.com web site and you will see that they strongly state that their products do not create any environmental problems.

Next is the very legitimate question of why do anything if the wood is already pressure treated. My thinking is to extend the life even longer by preventing splits due to aging. Also, the wood is getting quite light in color and I'm thinking that a preservative with a stain would blend better with the existing dark stairs near the dock.

The company representative I spoke to at length was quite knowledgeable and helpful. Final decision not made yet due to other considerations but the fact that the products can be ordered through Home Depot with no shipping charge is real plus.

Agree that the PT wood will dry out in 6 to 12 months. After that some sort of sealer is in order, clear or a stain. Without a sealer the wood will absorb rain water and then with the winter freeze small cracks will form. As the years go by the cracks will enlarge. A sealer will prevent this. As a test, pour some water on the wood. If it beads up, no problem. If it soaks in, time for a sealer be it clear or a stain.

Use whatever makes cleaning the "duck poop" easier. :D

must seal out water
 

Today's "enviro-friendly" pressure treatment is nowhere near as long lasting as the older pressure treated wood. My dock was done with the "new" PT wood and I'm replacing boards all the time from splits and rot and that started when the deck was about 5 years old. It is now 14 years old. Two years ago I decided I was either going to redeck the dock with one of the better synthetic decking boards or pressure wash and seal and try to extend the existing boards. The dock was black and many boards starting to split but I replaced all the marginal boards and pressure-washed and sealed the whole thing with Thompsons Waterseal. The whole dock went from black and old looking to like-new and has stayed that way for 2 years now, but may need a touch-up in some heavy traffic areas.

We had sealed our house deck with this product when it was new 15 years ago and the boards have never split nor rotted and still look like new today. The key is to seal the wood from water penetration as others have said. Newer PT lumber is going to not last otherwise. Whether Thompson's is the best product to use, not sure. It seems to do the trick, but if the wood is not dry when applied, it can flake off. Also, it's pretty odd when applying as it looks like milky coffee when putting it on, but dries clear, and water will bead off it nicely for quite a while.

The best dock preservative is a dock that's 100% aluminum, with maybe a couple stainless steel items attached. In the slightly acidic water of Lake Winnipesaukee, an aluminum dock will thrive indefinitely, and has a half life of 5000-years before the individual molecules that make it aluminum start to leach out..... so's you can expect an all aluminum dock to be very usable, and continue with a strong physical appearance for five to 10,000 years.