Before: Weathered and failed Sikkens coating
Before: Weathered and failed Sikkens coating
Always do a sample.
Always do a sample.
How it looks during final rinse, after chemical strip.
How it looks during final rinse, after chemical strip.
  • During the deck sanding step
    During the deck sanding step
Apply a high quality penetrating oil, following the mfr specs.
Apply a high quality penetrating oil, following the mfr specs.

This was one of our favorite and much anticipated projects of 2013 at Topcoat Finishes.

It was a decade or so old custom redwood deck in a harsh lakeside location with a badly failed Sikkens coating on it. The process of stripping a failed film forming coating is not for the faint of heart. Once you start, you are in it to win it.

Because decks are horizontal exterior surfaces, they have one of (if not THE) harshest weather exposure on the house. Often times, decks will hold up ok for a little while, and then fail quickly before the homeowner really knows it has happened.

Here are some guidelines that we recommend when hiring a professional for a redwood deck restoration.

1. Sample

In order to figure out how the deck will strip and refinish, we recommend doing a preliminary sample to ponder during the process.

At the very least, it is a good idea to sand out part of a deck board, and apply finish samples so that you have a sense of the end goal.

This way, you can select and purchase the desired finish so that when the deck is sanded, finish can be applied immediately. Trust us on this one, deck stain is a decision that you want a few days to ponder.

2. Pressure Wash – Chemically Strip and Neutralize

Honestly, the use of a pressure washer and stripping chemicals is best left to professionals with a track record of success in the field of chemically stripping decks.

The chems are hot, or caustic, and can do immense damage to people and property if not understood and used with discretion.

It is sufficient for the purposes of general discussion to say that chemical stripping is a two step process: stripping and neutralizing. If both are not done correctly and safely, the job will not go well.

The fundamental process here is a fairly radical chemical reaction in which the failed coating is released from the wood surface, and the ph balance of the wood is restored during the neutralizing step.

Stripping film coatings at this level is not a quick process. It requires many passes and reapplications of chemicals, and a great deal of clean water rinsing.

3. Let Deck Dry, Then Sand

It is important to allow a day or two of good drying weather before proceeding. Premature sanding of soft wood that is still any kind of damp can tear up the grain in a hurry.

Chemical stripping of decks raises the grain of the wood pretty dramatically. This is called "furring". For proper and even stain penetration, it is critical to remove the furring through sanding.

Depending on the size of the deck, sometimes an upright floor style sander is the most efficient method. If this is not an option, aggressive electric hand sanders are a also an option. It is time consuming, and knee pads are required. Whatever sanding method is employed, be sure that proper dust containment is used. Topcoat attaches all of its sanders to hepa filtered dust extractors made by Festool. There is too much funky dust of organic matter to risk breathing it in.

4. Apply New Finish

On softer wood species, we prefer penetrating oil finishes to bring out the depth of the wood grain. Clear or slightly pigmented blends that contain transoxide pigments are a great choice. Always apply finish per the manufacturers specifications (read the can).

Please feel free to use the comment section below if you have questions about how Topcoat can handle your redwood deck restoration situation.

We also service all manner of decks in other wood species with the same level of care and expertise.

Contact Topcoat for a consultation on your deck.

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Topcoat tests and reviews new product technologies, in many cases, months in advance of their release to the public. Our projects and state of the art shop facilities are the testing grounds for our paint tool reviews. For more information, visit topcoatreview.com