Old Canaan Building Materials

Not every cedar shingle installation is left to weather naturally. There are projects where the client wants the silver-grey of aged cedar from the day of installation rather than the two to five years it takes to arrive naturally. There are projects where the existing shingles on adjacent buildings are a specific color and the new work must match them. There are projects where the cedar is on a north-facing wall that will never receive enough sun to silver evenly on its own. For these situations, stain exists — and using it correctly requires understanding what it does and what it cannot do.

Cedar shingle stain is a penetrating finish — it soaks into the wood rather than forming a film on its surface. This is what distinguishes it from paint and from solid-color stain, and it is the property that makes it compatible with cedar shingles. A film-forming finish on cedar shingles will eventually peel as the wood beneath it moves, because cedar is a species that moves significantly with moisture and the shingles are exposed on both faces to different moisture conditions. A penetrating stain moves with the wood and does not peel.

Bleaching stains and bleaching oils are the most relevant products for traditional New England work. These products contain chemicals that accelerate the natural greying process of cedar, driving the wood toward the silver-grey of aged cedar more quickly than weathering alone would achieve. Applied at installation, a good bleaching stain will bring the shingles to an even grey within one to two seasons rather than the three to five years required for natural weathering. The grey it produces is not identical to naturally weathered cedar — it is slightly more uniform and slightly cooler — but it is close enough that from any normal viewing distance the difference is not legible.

Cabot Australian Timber Oil and Cabot's Bleaching Stain have been standards in the New England market for decades. The bleaching stain product in particular is widely used by architects specifying cedar shingle work on inland projects where the natural silver is the goal but the site conditions do not favor even natural weathering. TWP (Total Wood Preservative) makes a similar product. The formulations change over time as VOC regulations tighten, and the current versions perform somewhat differently from older formulations, but the principle and the result are the same.

Solid-color stains and paints on cedar shingles are a different category entirely and not part of the Old Canaan consideration for traditional natural-finish work. Painted cedar shingles — red, white, grey — are a legitimate aesthetic choice in some contexts, but they are a film-forming finish and they behave accordingly. They require repainting every five to seven years and they obscure the texture and the natural character of the cedar beneath them. For traditional New England work where the material's natural behavior is the point, paint on cedar shingles is not the correct specification.

Bleaching stain is most effective when applied before installation — either dipped or brush-applied to all faces and edges of each shingle before they go on the wall. This ensures coverage on the concealed portions of each shingle as well as the exposed face, and it allows the stain to penetrate fully before the shingles are nailed in place. Field application after installation is possible but less effective because the concealed portions of each shingle are inaccessible and the stain cannot be worked into all faces.

Apply according to manufacturer's instructions. One coat is typically sufficient for bleaching applications. Allow to dry fully before installation. Do not apply over previously stained or painted shingles without stripping — the stain must penetrate raw or previously unfinished wood to be effective.

On coastal properties where salt air will drive even natural weathering, bleaching stain is unnecessary. The shingles will arrive at an even silver-grey on their own within two to three seasons, and the naturally weathered result is indistinguishable from the stained result. Save the stain for inland projects where the weathering conditions are less favorable.

Do not use bleaching stain as a substitute for properly specified cedar. Extra grade, re-butted and re-jointed eastern white cedar will weather evenly whether stained or not. Lower grade cedar with more variation in density and resin content will weather unevenly regardless of what stain is applied. The stain is not a correction for the wrong material.