Sealing a composite deck is fairly easy, I have had good rusults using the siloxane type sealer SUPERSEAL-M. It penetrates well and seals the pourous surface creating an impermeable barrier for rain, wheather, falling tree matter, and what have you. Again this is my opinion, not the only solution. Another great quality of this product is that basically you can spray it on almost any adjoining surface without harm, when it dries it is invisable. This is only one of the many clear products available for this situation.

When you seal out the water with a composite deck sealer you also minimize or stop the mold and mildew that is prone to composite wood.

Can you please explain more about what happens when you do not make sure that you seal the deck properly. How do you ensure that you have an even coat and that you are getting the proper coverage?

Most composite decks use a clear coat to help proect against mold since these type of decks are pre-tinted and made of recycled plastic and wood fibers. When applying a clear coat without any tint it is very easy. When applying a tinted stain it is best to apply with a deck stain pad to achieve uniformity while minimizing over application.

Totally clear sealers are fairly easy as you can apply it allmost to the point of puddling and roll or pad it evenly. Tinted sealers soak in and you can see where you have missed, simply coat the area, spread it out with a pad, roller, brush, or applicator of your choice, dont over apply, and you should be good. Some sealers recommend two coats, and the same procedure should be followed as the first except for the second will spread about twice as far.

Do you normally use a clear on the trex decks or do you use a tinted sealer. Why would a customer want to use a tint on the trex? Isn't it already permanently stained when you have it installed?

Some of the older composites faded from their original color, to a very dull somewhat chalky look, so, some companies came out with composite stains so these people could have vibrant colors restored to their decks. I still see alot of fading on these types of decks, but the technology seems to be improving somewhat. Mold inhibitors are now mixed in with the composite, but as with any outdoor surface, these inhibitors will eventually break down and the mold will grow, mold will grow on any surface given the right conditions, and that is where the regular cleaning and sealing of a composite deck will keep it safe, clean, and nice looking.

Composite deck sealers protects deck against mildewstains, bbq stains, uvrays, dirt and grime, water damage and floor fade. Some products contain a very effective mildewcide to arrest the groth of the mildew.