Conversion Varnish

Good Morning Folks.

I saw the term Conversion Varnish in a description of a Sheppard mandolin, and I am not familiar with the term. Of course, being a good American, I googled the term and watched a youtube video.

What I got from all this was that the CV uses a two part system with a catalyst, has higher solids than Lacquer, higher expense than lacquer, and was usually about twice as thick as lacquer yet more elastic. I realize thickness is application dependent.

Any opinions on this finishing material? Opinions? Us? I know.....

Disclaimer: I am not a builder. I am curious.

Sounds like a great product!

Let us know in a hundred years how it's held up. If it is the sane stuff as used on one of my newish instrument, it might as well be a plastic mandolin, look and feel wise. But I tend to be a grouch when it comes to plasticlike instrument finishes.

Anybody else? With an opinion of an educational nature?

Wayne Henderson and Jimmy Edmonds use a conversion varnish that is acid catalyzed. It produces a brilliant, durable finish that is much less work to create than traditional lacquer. As mentioned, it is a high solids finish, and it sands and polishes very easily. However, there are two problems that will prevent me from trying it. Number one is the tendency to turn certain examples of Brazilian rosewood bright green. It almost looks fluorescent, and in some cases, the effect doesn't show up for months later.
The other problem is that it sometimes has a milky appearance, especially when viewed at low angles with bright lighting.

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Sounds like a great product!

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If it's a product, who makes it? I'm still wondering what "conversion varnish" really is. Catalyzed polyester—any kind? I've seen green fluorescent Brazilan that did that light show under nitro and French polish, so I wouldn't hasten to attribute the phenomenon to the finish. Anyone got brand names, or more specific (not anecdotal) information?

I had a can of such lacquer years ago... My uncle worked for a large furniture producer and had large barrel of it so he gave me some for my first guitar "project". He called it "acid hardening" nitro lacquer. He added hardener into the can and it worked perfectly on the guitar, just like nitro, just faster drying (almost like poly). It had nice natural color that aged to slight amber just like with regular nitro. He told me it was great specifically for their MDF parts as it dried on top rather than soaking in and making it fuzzy. No brand name, though (Probably different here in EU than what OP saw). I'll ask what it was...

Years ago (25?) I used a product called conversion varnish. It was made by Sherwin Williams. It sounds like similar to what the OP was talking about. It was very tough stuff. It was also so toxic and nasty that a regular respirator wasn't good enough. You had to wear a whole facemask or your eyes would burn. The stuff, once the catalyst was mixed in, had a pot life of about 72 hours, IIRC. Had to get things cleaned up in a timely manner or your equipement was ruined.

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Originally Posted by Dale Ludewig

Years ago (25?) I used a product called conversion varnish. It was made by Sherwin Williams. It sounds like similar to what the OP was talking about. It was very tough stuff. It was also so toxic and nasty that a regular respirator wasn't good enough. You had to wear a whole facemask or your eyes would burn. The stuff, once the catalyst was mixed in, had a pot life of about 72 hours, IIRC. Had to get things cleaned up in a timely manner or your equipement was ruined.

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Looks like some form is still available HERE and HERE

and possible others. Just go to the sherwin-williams site ans search for "conversion varnish" or go HERE

Alan D.

That's the stuff.

Wow. The MSDS on the SHER-WOOD® Water White Conversion Varnish (UV Absorber Added), Gloss looks terrifying.

I'm still wondering about the fluorescent green phenomenon in BRW John mentioned. I've seen it in a few old Larson Brothers guitars, and an array of modern instruments, all of which I discovered were made from BRW purchased from one dealer, DiGiorgio. I had the good fortune once to discuss that wood with Mr. DiGiorgio and he offered an interesting background on the 800 or so sets he had had of it, all of which came from three huge trees in a single cluster. Some (that I saw) were finished in nitro normale, some in 2-part catalysed finishes—so I suspect it was the wood, not the finish. Certainly the Larson Brothers guitars weren't finished with a modern finish, but they sure flashed green in direct sunlight and under artificial UV. Bob Taylor made a few guitars made from that DiGiorgio wood, Stefan Sobell got a lot of it, Dana Bourgeois also had built with it. I actually really like the look.

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Originally Posted by Paul Hostetter

Wow. The MSDS on the SHER-WOOD® Water White Conversion Varnish (UV Absorber Added), Gloss looks terrifying.

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Looks like pretty standard solvent fair to me - bare in mind that exposure to almost all solvents (including the alcohol we all FP with) is bad for you. Used in a properly ventilated space they're fine as long as your not actually bathing in the stuff. Come to that a lot of the old time Chemists did use to regularly wash their hands in benzene, toluene or whatever came to hand, not recommended, but seemed to do strangely little harm.

I do FP with ethyl alcohol, which if you drank enough of it straight could mess you up, but it's otherwise fairly harmless. The other aromatic hydrocarbons seem way more dangerous than what's in standard lacquer thinner or acetone.

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Originally Posted by Dale Ludewig

The stuff, once the catalyst was mixed in, had a pot life of about 72 hours, IIRC. Had to get things cleaned up in a timely manner or your equipement was ruined.

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So this seems to be different from the acid hardening lacquer I had. My uncle mixed it for me when he gave me the can and I used it at least two weeks later with no problems. I recall we thinned it with acetone.

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Certainly the Larson Brothers guitars weren't finished with a modern finish, but they sure flashed green in direct sunlight and under artificial UV.

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What you are describing is fairly common in BR, and not anywhere near the same degree that I have seen with this finish. It is plainly visible under any lighting. My use of the word 'fluorescent' is a description of the bright green color, not to indicate its appearance under UV light. That said, it would not surprise me if the effect were even more pronounced under those conditions.

The reason I am blaming the finish for this phenomenon is that I have never seen anything like it with other finishes. Some of the BR sourced from me has done it....BR that I have never experienced the problem when using conventional lacquer. It has caused the luthiers I mentioned to consider refinishing some of the affected guitars.
The reason I have not made the effort to find out exactly which products they are using is that I want no part of it.
There are at least two different brands or types that have shown this effect.

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So this seems to be different from the acid hardening lacquer I had. My uncle mixed it for me when he gave me the can and I used it at least two weeks later with no problems. I recall we thinned it with acetone.

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That does fit the general description. The solvent is acetone or lacquer thinner. The catalyst smells like vinegar. Pot life can vary with different formulations.

Here's one from Mohawk...
http://www.mohawk-finishing.com/cata...asp?ictnbr=577

You can get the MSDS and PDS by clicking on the links on the right. I've been looking into whether and how to repair this stuff. I have an Ovation guitar in for finish repair and I've discovered that it's not at all easy to repair. With nitro lacquer, just add some butyl cellosolve and spray. With varnishes it's even easier. But with this catalyzed poly you really can't apply anything and be sure it will bond. Once this stuff is on, it's a rock. I've since found that Bourgeois and PRS, and of course Taylor, among others, are using these finishes. I'm not sure about small mfgs like Huss and Dalton. It's only a production shortcut, as these finishes build faster and can be buffed 24 hours after application. But they must also be re-coated within 4 hours or you won't get a chemical bond. I know that Collings still uses nitro lacquer, I think Rockbridge does as well.

I would avoid these finishes due to the fact that they are very difficult to repair without witness lines and debonding of new finish. I think I'd varnish everything with oil varnish or just use French polish if time was no issue at all. But guitar people expect lacquer, mandos and fiddle expect (or want) varnish.

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I know that Collings still uses nitro lacquer,

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My latest info is that Collings uses a UV cured finish (polyester?) as an undercoat to build a level surface. Nitro is sprayed on top of it.

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I've since found that Bourgeois and PRS, and of course Taylor, among others, are using these finishes.

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Taylor also uses a UV cured finish.

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Originally Posted by John Arnold

Taylor also uses a UV cured finish.

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Yep. Just patched a big hole in the side of a Taylor guitar, and told the guy up front that I couldn't really fix the finish. I finished the repair with superglue, and all in all, it doesn't look too bad. Lacquer sure would'v been easier...

I thought conversion varnish is when they add varnish in with lacquer to get a compromise in how finish affects the durability/tone of the instrument and for ease of application. I like the look of the finish on the Sheppard you mentioned...

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I thought conversion varnish is when they add varnish in with lacquer......

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I cannot imagine that mixing varnish and lacquer would have a satisfactory result. The problem with the word 'varnish' is that it refers to finishes that can be as different as night and day.

Conversion varnish? Got me. I never heard of such a thing. I would suspect that it is a product that is supposed to be an alternative to regular old oil varnish that dries quickly. I wonder what it is converted to or from.