MANWORKS How to Finish Cedar

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Thanks to Lanark Cedar and Canadian Homes and Cottages magazine for technical data on this article.

Step #1: Assess yourself. Do you really have the time and ambition to maintain a wooden deck finish?

Step #2: Choose a deck finish that has proven itself effective through independent scrutiny.

Make sure your wood is ready:

New wood does not respond well to finish nor does wood that has been allowed to turn grey. According to research, the only independent testing of deck finishes has been Consumer Reports, which has been surveying results for almost 10 years. (See below)

A moisture content of less than 14 per cent and a surface that is absorbent and receptive is required. Even if wood is very wet when purchased, a few weeks to a couple of months of summertime drying should reduce the moisture content sufficiently.

Milled lumber will have a degree of burnish or “mill glaze” caused by the spinning action of planer blades. This glaze prevents liquid from penetrating as deeply as it should and thus premature peeling is a possibility. There are chemical mill glaze removers available to increase surface absorbency, or you can sand your cedar before applying a finish. Experience tells me that most people are not likely to do this. Instead, allowing the wood surface to sit is the most effective way to open the pores, allowing the finish to soak in more freely.

However, this may cause other problems. Once wood begins to turn grey, it indicates that surface fibers have loosened. While the wood may be thirsty, it is loose which will cause the finish to flake or peel. Try to stain your deck or fence before it begins to turn grey.

Finishes:

Three main types of deck finishes: clear transparent formulations, semi-transparent products and opaque deck finishes.

Clear, transparent deck finishes attempt to keep new wood looking that way but have little or no protective surface film to protect against ultraviolet rays. “Olympic Water Guard 57560C is the only clear deck finish that has proven at least a good appearance over a three-year period”.

Tinted, semi-transparent products offer greater durability and allow some visibility of the wood grain. “The current available-in-Canada leader in this category is Sikkens Cetol SRD”.

Opaque paint-like finishes offer the greatest durability and protection against UV. “Cabot Decking Stain has claimed the lead in this category for a number of years running”.

”Most people are surprised to learn that deck finishes don’t do much to extend wood life. Finishing your deck is an aesthetic thing, and that means that natural weathering of wood is okay as long as that grey, barn board appearance is acceptable to you”.