Shellac questions for Brian Howard

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Shellac questions for Brian Howard

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Brian,
Here are a couple of URLs that point to formulations of shellac. One is traditional high gloss and the other is a low gloss finish. I'm wondering what your opinion is of these products. Specifically, whether these products are breakthroughs and worth exploring or a marketing-speak for standard, but perhaps, not well known formulations that can be made up by the average guy? Thanks!

Alcohol and heat resistant Royal-Lac and Seal-lac
http://www.shellacfinishes.com/shop/

Low gloss shellac finish
http://www.shellacfinishes.com/coming-soon/
B. Howard
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Re: Shellac questions for Brian Howard

Post by B. Howard »

http://www.shellacfinishes.com/shop/
Appears to be a very traditional shellac, I see no mention of any modifying resins being added. They do not list the cut either so how much shellac you actually get is a guess. As with all pre-mixed shellacs, freshness is always a concern. Some will have preservatives added to increase shelf life. I do not see any type of preservative listed on the MSDS so shelf life of unused product may be fairly short. That said, I don't have a problem with pre-mixed shellacs. I have and still use them on occasion.

http://www.shellacfinishes.com/coming-soon/
This is something you see from time to time....but it never seems to really catch on. Most people interested in a satin finish would rather simply brush or wipe on two coats of polyurethane than mess with shellac. The ones I have seen in the past were always a bit soft when done for my liking. This one mentions the use of synthetic resins. I imagine this is possibly some nitrocellulose or glyptol so it can receive a conventional flattening paste. It is the flattening paste that softens the finish. This is true of any non catalyzed finish. I also see the mention of a water borne version. Which tells me the synthetic resin content may be quite high, as that is the only efficient way I see to keep shellac dissolved in a water based product. Which then questions is it really a shellac?

People have been adding modifying resins to shellac since forever. Sandarac to harden it, copal to improve abrasion resistance, pine pitch as a filler just to name a few. At which point these coatings stop being a shellac and become a spirit varnish is a matter of opinion. Most spirit varnishes can still be applied in a conventional FP method. They will however age differently and this will vary by blend. This is why most violin makers develop their own special variety and then guard its composition like a state secret. I personally like shellac buttons for my FP as the process to produce the buttons polymerizes the shellac and adds some of the benefits of a modifying resin without the hassle.

As to the claims of heat and water resistance from their main page, I agree. I have always stated that a properly done FP finish is just as durable of an interior finish as nitro. This is not specific to their product but equally true of other brands of pre-mixed shellac and those we mix ourselves. The FP process when done correctly will by its nature produce a very tight and impervious coating. Most of the bad reputation these finishes have gotten comes from the fact that so many, even some of those I see done by other professionals, are just poorly done or simply not completely finished. IMO shortcuts like spraying or brushing the first few coats definitely have a negative effect on film integrity.
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Brian Howard
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Tom West
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Re: Shellac questions for Brian Howard

Post by Tom West »

Currently there is an ongoing thread about some of these products on the Official Luthiers Forum. Worth a look, and to me shows a company who knows how to give product support.
Tom
" A person who has never made a mistake has never made anything "
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