Waterborne and solventborne coatings come in two varieties: reactive and non-reactive. The reactive variety of wood coatings contain catalysts. Catalysts allow the molecules in the coating to bond together much tighter, which produces a more durable, better performing coating.
Waterborne wood coatings have been available for years as either acrylic or acrylic/polyurethane blends. Non-reactive waterbornes, as their title states, don’t react with anything. They just cure through evaporation, because no chemical catalyst to activate the curing is involved. We see these in both brush and spray-grade products.
At the July AWFS Fair woodworking show in Las Vegas, we entered the new age of low Volatile Organic Compound (VOC) coatings. This is the result of an explosion in new resin technology. This year at the fair, M.L. Campbell introduced a zero formaldehyde post-cat clear wood finish.
It has earned GreenGuard certification. The new product, called EnviroVar, is also one of the recipients of the 2011 woodworking industry Sequoia Awards. Congratulations to them for their achievements.
Also, Sherwin Williams introduced its Sher-Wood F3 Kemvar Varnish at AWFS. Sherwin Williams market director David Kennedy described the F3 Kemvar as a “formaldehyde-hazard free, isocyanate-free finish that eliminates the need to change equipment or processing set-up, or sacrifice the aesthetics of traditional catalyzed coatings.”
Kennedy says the growing impact of regulations and specification programs that reference stringent limits on formaldehyde emissions means you will increasingly need to be able to provide this type of formaldehyde hazard-free, high performance finish option to your customers. “For these finishers, the ability to offer wood products with no post-cure formaldehyde emissions can be a significant differentiator in their marketplace and open up new opportunities with a wider range of consumers,” Sherwin Williams said in announcing F3 Kemvar Varnish.
These two products result from the need to make the rather benign (and at times temperamental) non-reactive waterborne coatings perform at the same levels as good solvent-borne pre-catalyzed and post-catalyzed coatings.
As we have noted before, a pre-cat coating is one that arrives at your door from point of purchase with the catalyst already mixed into the pail. A post-cat is one that you have to mix in batches to add the catalyst just prior to application. The reason for the existence of the two forms is that catalytic reaction is finite in length. Once it ends, the coating no longer performs per specification.
Such chemical reactions are common in wood finishes. The positive outcome of this chemical reaction is a more durable, chemical and water resistant finish. The negative outcome is that both pre-cat and post-cat solvent technology produces formaldehyde to some degree or another.
But formaldehyde is an indoor air pollutant. Products that release formaldehyde are not going to help your shop earn LEED points for your clients.
Now, technology has come to the point where we can still have the strong finish film that the acid and the urea resin combination create. But the new resin technology has erased the formaldehyde release. Welcome to the era of zero formaldehyde release coatings!
Until next time…spray on!
Bernie Bottens (WoodworkingNetwork.com/blogs) teaches wood finishing in industrial woodworking to shop owners, foremen, spray technicians and finishers all over the Pacific Northwest. He is wood finishing specialist with Wurth Louis and Co., Portland, OR. Reach him at email@example.com.
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