Thorough stripping and cleaning of any deck or fence is essential to get good results when sealing or staining. If the deck was previously sealed, the common practice is to strip off the old sealer to remove stain and other products on the surface. We do this to get back to the actual wood. All sealers are designed to bond best to the wood itself (rather than to bond to an aged layer of the old sealer). By stripping off at least the “coating” portion of the old sealer, we can eliminate most reasons for premature sealer failure.

If the “coating” portion of the old sealer remains on the surface, the new deck sealer can penetrate down into the wood. This results in a couple of situations that could lead to premature failure of the new finish.

The first of these problems is a reduction of the permeability of the overall sealer layers. Permeability refers to the ability of the sealer to breathe. If we clog the surface with several layers of sealer, each layer comes a little closer to closing off the wood from breathing. In that case, the wood retains humidity. This could lead to rot, as discovered in a recent class-action lawsuit against a major manufacturer of sealers. This could also lead to peeling and flaking, as the trapped humidity tries to push its way up through the layers.

The second problem is bonding. As stated earlier, most deck sealers are designed to bond to wood fibers to some degree. Many sealers can also bond to themselves (such as a second coat). If we try to apply one sealer over top of another brand (or type) of sealer, there is no guarantee that the new sealer will bond to the old sealer. If this occurs, the new sealer could flake and peel off within months. Most sealer manufacturers are reluctant to stand behind the performance of their product unless it is applied to bare wood.

Further, sealers that are designed to penetrate, when forced to dry on the surface without penetrating, will fail by design. What I mean here is that a penetrant is not meant to stand up to wear like a coating does, so when you force a penetrant to act as a coating it fails. This happens when the penetrant can't penetrate - and it dries on the surface.

There is at least one more reason to think about deck stripping every time you run across a previously- sealed deck. The reason home owners call us is because they are unhappy with the performance and/or looks of the current sealer. Leaving that old sealer in place seriously limits how good we can make the deck look with a new finish.  To prevent future problems that will require deck stripping again, we use Ready Seal deck sealer.  Contact us for more information about our deck stripping and pressure washing services.