[GSBN] Sealing wooden floors

[Derek Stearns Roff]

You may need to get a more precise definition of what the clients are thinking when they say "no VOC".  No wax can be applied to wood without being dissolved or emulsified in a solvent.  Or using significant heat, which would be impractical on a floor.  "Solvents" are identical to "VOCs" in the minds of many consumers, even if the technical distinctions are a bit more subtle.  Very few clear finishes can be applied without VOCs, and those that make the claim are often cheating a bit in their definition.  I think it is important to limit the VOCs, but also very important to choose products made with the less toxic and less problematic VOCs.

My first layer of finish on wood is almost always shellac.  This is a completely natural product, sufficiently non-toxic to be allowed for human consumption on many foods, such as M&Ms.  It is applied via the solvent ethanol (mostly, sometimes with a few other alcohols to make it non-drinkable).  An advantage of this alcohol solvent is that it will all be gone from a ventilated space in 24 hours.  De-waxed shellac is an excellent sealer and binder, and can be applied below any common finish.

The middle layer is the problem.  This is the layer that has the greatest thickness, the longest cure time, the highest cost, and will take the majority of the wear, if owners don't apply wax on top of it.  This is the layer that the owner will want to re-coat from time to time, when they decide to "refinish their floors".  I haven't found a product that meets all my criteria and desires.  I just checked on a product which has seemed promising.  It claims to be a "Clear, non-yellowing, odorless, hard-wearing, zero VOC varnish finish."  It is also listed as "NOT AVAILABLE".  Several other promising products that I have tried or investigated have quickly gone off the market.

Note the irony of pure linseed oil, when applied with no solvents at all.  It is a completely natural and non-toxic product, yet it releases organic compounds as it cures, whose odor many people find at least mildly objectionable.  Food-grade oils have milder odors, generally.  The odor may be detectable in the finish more than a month later, and in an enclosed space like a closet or drawer, it can persist for years.  In addition, it takes many coats and a lot of cure time, to build up a finish of natural oils, such as linseed oil or tung oil, to the thickness that the average client would call "long-lasting"

A low-VOC varnish is probably more credible than a zero VOC varnish, although I keep hoping to find the latter in a good-quality product.  I've liked many BioShield products over the years, and they don't seem to offer a no-VOC clear wood finish at the moment.  I haven't used their "Aqua Resin", but it is described as a "Dispersion of Polyurethane in Water,  Alcohol, Micro Wax, Silicic Acid, Silicone,  Anti-skinning Agent. Product contains less than 115 Grams of VOC per Liter."  It costs a bit less than $100 per gallon ($66.40 for 2.5 liters, $215.00 for 10 liters/2.6 gallons), which is a bit above average for similar floor finishes.  Vermont Natural Coatings has a low-VOC floor finish call "PolyWhey", with "VOCs less than 180 g/L".  PolyWhey was in BuildingGreen's Top Ten Products list of 2008.  It sells for $70 a gallon on Amazon.com<http://Amazon.com>, plus another $11.40 for shipping.  Vermonty Natural Coatings prefers to sell through local dealers, and their website lists one in Albuquerque, none in Santa Fe when Danny lives.
[cid:80302EB8-5C47-419A-BF7C-2FBA1B2AA259 at domain.actdsltmp]
SouthWest Green Building Center
5620-L Venice Avenue NE
Albuquerque, NM  87113
505-821-6259
http://www.swgreenbuildingcenter.com/

My final finish layer is usually wax, and I lean toward waxes high in carnauba wax (from the Tupí language of Brazil, it's one of my favorite words, sometimes spelled "carnuba").  Waxes are borne in various solvents, and I try to find one with low toxicity that evaporates quickly, doesn't have prolonged outgassing, and whose vapors do not tend to be absorbed into other things found in the home, such as carpeting and furniture.

I think those who want a maintenance-free floor finish to be delusional.  A hard wax like carnauba is an excellent surface finish, on top of the two layers mentioned above.  It needs to be reapplied in high traffic areas as needed, which might be once every month or two, or more often if you have energetic kids and a labrador retriever.  If you maintain the wax layer, then the varnish layer can last indefinitely.  A light sanding and an additional coat of varnish every five to ten years fits my standards for "long-lasting".  The shellac layer never needs to be redone, unless the wood is sanded through all of the finish layers, or chemically stripped.

I would be interested to hear other products and approaches to finishing a locally-milled wood floor.

Derek

On Feb 18, 2013, at 10:14 AM, Danny Buck wrote:

We have some fir floors made of timber we harvested on site and milled. The owners want a long-lasting no VOC finish for them. Has anyone had success with wax? Other products?

Thanks,

Danny Buck
President, Daniel Buck Construction
Santa Fe, NM

Derek Roff
derek at unm.edu<mailto:derek at unm.edu>


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