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Spirit varnish without shellac


Michel Aboudib
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I am looking for a spirit varnish recipe that does not contain shellac. I am a guitar maker. I usually French polish with a shellac based varnish that also contains other resins. For this instrument, however, I can’t use shellac due to the believes of my client (please don’t make this the focus of the conversation).

I tried modifying a sandarac based recipe, but the varnish was easily scraped off.

I also tried sandarac turpentine and elemi (in alcohol), with the same results.

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10 hours ago, Michel Aboudib said:

I tried modifying a sandarac based recipe, but the varnish was easily scraped off.

Was this applied to the guitar or did you try your recipe on scrap wood?

The issue with using the guitar for testing your finish is that the soundboard surface will retain some finish while in other areas it appears it is removed but not really.  So it all looks the same until you go to put a finish over it.  Then blotchy areas appear - very disheartening.  Some people don't care but for a maker results should be better.

I've had good results using an oil based wood varnish, let cure for a long time and then apply nitrocellulose over the oil varnish {sprayed}.  The oil must be cured or dry/hard firstly.

An acrylic water based semi- gloss or gloss polyurethane will almost be fool proof for all of the parts other than the soundboard - too difficult to get smooth.  At least it was for me. 

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4 hours ago, uncle duke said:

An acrylic water based semi- gloss or gloss polyurethane will almost be fool proof for all of the parts other than the soundboard - too difficult to get smooth.  At least it was for me. 

What is the recent fixation with tops being smooth? Isn't a smooth top one of the easiest ways to identify the cheapest of the  factory instruments?

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I know that a popular finish among guitar makers these days is Epifanes gloss clear. It's supposedly/possibly a polyurethane/tung oil varnish and dries overnight without light. It's tough, but you can't French polish it (move surface with alcohol) at all--the polishing has to be mechanical.

Most spirit varnish possibilities that I could think of making without shellac would not be that great in some respect or other--usually a lack of even basic durability. Shellac is a really wonderful material in a way that other spirit-soluble resins aren't. In spirit varnishes shellac adds the same kind of tough flexibility that oil adds to oil varnish.

David, I don't think non-smooth guitar tops was ever a thing, unless recently when I haven't been keeping track as much as I did when I was making guitars.

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I think the answer is yes. And further, following lute tradition, the one in Vermillion has colored varnish on everything but the top, and I'm going to guess that the top originally only had an egg white glaze, as on lutes. And I think the first modern classical makers in the early 1800s had smooth tops, too.

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15 hours ago, David Burgess said:

What is the recent fixation with tops being smooth? Isn't a smooth top one of the easiest ways to identify the cheapest of the  factory instruments?

About 25 years ago I saw one of the Cordoba's fine pieces of work for sale here in K.C. -  appeared to be perfectly finished but don't recall if it was oil, shellac, or nitro used.

Identifying cheap for me is to look at the rosette first.  Is it a decal or real wood.  Next would be does the guitar allow playing above the seventh fret, ninth fret, twelfth fret?  Consider playability at the fourteenth fret a real bonus with these cheaper pieces of work.  

For violin I like my dirty homemade varnish - it's not a Daryl G. looking varnished fiddle when all said and done but I'll get there one day.   

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Not to make this the topic, but if you're tacking about something like vegan beliefs, you might remind your client about hide glue.

Back to the subject. Urethanes and many synthetic finishes are made from oil. A nitrocellulose  lacquer might work for you. What about a nice Japanese Urushi lacquer (toxicity)?

https://guitar.com/guides/essential-guide/all-about-nitrocellulose/

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16 hours ago, David Burgess said:

Do Stradivari guitars have smooth tops?

I'll agree with Michael's observations.  My memory of the one in Vermillion (from 8 years ago) is that it does.  The lighting in these photos does not show surface texture at all, but there is also no indication of dirt in low areas of grain like there is in the dents etc.  Of course someone might have sanded it...

https://emuseum.nmmusd.org/objects/7192/guitar?ctx=61cd4eb6-48d1-48b9-8c7d-e71287c95d12&idx=2

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2 hours ago, Mark Norfleet said:

I'll agree with Michael's observations.  My memory of the one in Vermillion (from 8 years ago) is that it does.  The lighting in these photos does not show surface texture at all, but there is also no indication of dirt in low areas of grain like there is in the dents etc.  Of course someone might have sanded it...

https://emuseum.nmmusd.org/objects/7192/guitar?ctx=61cd4eb6-48d1-48b9-8c7d-e71287c95d12&idx=2

Four or five steps into that photo sequence does reveal what appears to be dirt accumulations, corresponding to "reduced-level winter grain lines'.

So far, I have reached out to the curator of the Ashmolean Museum, the curator of the National Music Museum in Vermilion, (both of which have Stradivari guitars) and Charles and Peter Beare. Next will be Andrew Dipper, who somewhat specializes in early instruments. It will be interesting to see what comes out of all that, if anything.

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I made an inquiry this morning of the shop that did the restoration on the 1679 "Sabionari" Stradivari guitar that's being promoted as being the only playable Strad guitar (check youtube), Sinier de Ridder, in France.

Francois quickly got back to me saying that he'd examined the three European examples of the Strad guitars before doing the work and he was of the opinion that the top wood was treated the same as the violins (that implies a scraped, corduroy finish, I think, though there isn't any evidence of that remaining on those examples) but that this wasn't clear on them because they'd all obviously seen a lot of use, wear, and repeated cleaning. He also commented that as in the contemporary guitar practice of the time there would have been no varnish on the top, ever, only egg to prevent the wood from getting dirty and turning grey. 

He commented on some other aspects of the restoration, the most interesting being that there were modern wood replacements by Marconcini, and that all of these had been devoured by worms which didn't touch the original Stradivari wood!

Check out their website. It looks like they are involved in some incredibly interesting projects:  https://www.sinier-de-ridder.com/

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On 10/25/2020 at 6:47 AM, Michel Aboudib said:

I am looking for a spirit varnish recipe that does not contain shellac. I am a guitar maker. I usually French polish with a shellac based varnish that also contains other resins. For this instrument, however, I can’t use shellac due to the believes of my client (please don’t make this the focus of the conversation).

I tried modifying a sandarac based recipe, but the varnish was easily scraped off.

I also tried sandarac turpentine and elemi (in alcohol), with the same results.

The guitar top has different needs from violin's. Problem are nails and secondly, violin needs more elastic varnish than guitar's top. As you said, Sandrac varnish is soft. Elemi is soft too. So problem no 1 is that you use soft resins. Shellac, Copal, amber etc are harder, but from them only shellac is proper. 

Althought, Sandrac + turpentine or alcohol (without elemi or other soft resin) are not bad choices but I don't know what recipe you used. 

The comments above are all right. 

Look above for an alternative with tru oil etc:

http://www.mikeouds.com/messageboard/viewthread.php?tid=12156

http://www.mikeouds.com/messageboard/viewthread.php?tid=12229

Think about burnishing - and no varnish at all. 

Also, go to older (pre medieval) receipts as egg yolk+ linseed oil+levander. 

Lutes, (and ouds) before shellac era had egg as protective layer. 

 

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1 hour ago, TJ Fuss said:

The other possible objection I could understand would be the working conditions and wages of the people harvesting and processing the shellac.

I didn't consider that becaause the argument that people will be better off if I refuse to buy their product and thereby deprive them of any income at all is a strange one to me.

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On 10/25/2020 at 9:17 PM, Michael Darnton said:

I know that a popular finish among guitar makers these days is Epifanes gloss clear. It's supposedly/possibly a polyurethane/tung oil varnish and dries overnight without light. It's tough, but you can't French polish it (move surface with alcohol) at all--the polishing has to be mechanical.

Most spirit varnish possibilities that I could think of making without shellac would not be that great in some respect or other--usually a lack of even basic durability. Shellac is a really wonderful material in a way that other spirit-soluble resins aren't. In spirit varnishes shellac adds the same kind of tough flexibility that oil adds to oil varnish.

David, I don't think non-smooth guitar tops was ever a thing, unless recently when I haven't been keeping track as much as I did when I was making guitars.

More than few folks apply Epifanes (or similar oil varnish) and after final smoothing with 400-600 grit they apply several wiped layers of Tru-oil and buff that out. You can buff the Epifanes but you can get witness lines easier than with the Tru-oil top coat.

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35 minutes ago, Michael Darnton said:

I didn't consider that becaause the argument that people will be better off if I refuse to buy their product and thereby deprive them of any income at all is a strange one to me.

I agree. Back when the internet was young, I was involved in the Old Tools List (an early email list group of collectors and users of old hand tools). We did a group buy that one of the members arranged directly with the source in an attempt to get more of the money to the producers. I still have several lifetime's supply of almost every shade of shellac flakes possible.

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Thank you all so much for your replies and your research. Well, you guessed it, it is about veganism and my client knows what shellac is and I didn’t use hide glue or fish glue in his guitar (or bone).

He does want a shiny finish (as in guitar shiny). So I guess the best option is nitrocellulose laquer. Urushi would be great but a bit too pricey for this project.

Actually I left out an important information—mostly because I really wanted to know about non shellac possible spirit varnishes—The guitar has a few coats of tru oil (gives it a beautiful satin finish). It was finished that way first then my client decided he would prefer shiny.

The mixture of sandarac and other resins I tried was based on the Watin spirit varnish that I tried to adapt. So really from the tests I made it seems few things stick to anything like shellac does.

Here’s what it looks like now (the clear pickguard is temporary). Shiny would definitely look great on that rosewood.

Front.jpg

15092020-_DSC2822.jpg

15092020-_DSC2821.jpg

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Nice. I like the disintegrating rosette! And the ziggy-zaggy bridge!

You should know that you might have trouble with nitrocellulose directly over oil varnish. Nitro is susceptible to failing to harden in such a situation, as it can pick up the oil as a plasticizer.* This can happen if the oil isn't totally dry, or also because lacquer thinner is a solvent for oil, even when it's dried. This might be pointing you back to a polyurethane based finish.

Regardless, there might also be adhesion problems with anything you use that isn't also oil-based.

Both of which lead back to Epifanes. . . .

 

*factoid: if you use a 60s hippie cloth guitar strap with plastic on the inside, don't store it with the plastic against the guitar--the plasticizer will leak into the guitar finish and leave a soft stripe up the back! Nitro LOVES plasticizers.

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On 10/25/2020 at 11:09 AM, uncle duke said:

An acrylic water based semi- gloss or gloss polyurethane will almost be fool proof for all of the parts other than the soundboard - too difficult to get smooth.  At least it was for me. 

I experimented with water-based poly-acrylics and they gave crystal clear finishes. Every detail of fine and complex grain came through. But as you noted, they are difficult to get smooth.

The basic problem is the short drying time (about 2 hrs) which means a short working time and lack of ability to "level" as they dry. I could not develop any type of French Polish technique to get it flat. There were always witness lines in the final direction of the rub (or brush).

Also, poly-acrylics require some light sanding to the initial surface since they stick primarily through mechanical bonding. This can be a no-no if dealing with a fine colored varnish finish that you want to polish up with the poly-acrylic.

I did achieve some degree of success by putting on a few coats, then carefully and progressively sanding from 600 grit to 3000 grit, and finishing with a good quality auto-paint polish. Because poly-acrylics go on so thinly, one must be careful not to sand through the layer to the underlying wood or colored varnish. Also, it is extremely important to remove every last spec of sanding dust before applying another coat or else it dries with tiny holes that look like areas of missing varnish.

Unless there is some special need for wear or chemical resistance, I found it a lot simpler to polish up an oil finish with a dilute solution of clear shellac rather than deal with all that sanding and careful cleaning. Shellac is remarkably durable and can be easily refreshed.

Another option I explored that might be of interest to the OP is modern oil-based spar varnishes. They have a long work time and dry flat without any brush witness lines. They have excellent leveling characteristics, dry overnight and once thoroughly dry can be easily sanded or polished to get various degrees of gloss. Most also add UV aging protection.

A down side is that they create quite a thick layer with each coat. I had some limited success with various diluting liquids, like mineral spirits. Perhaps a thickish layer is not an issue with the back of a guitar or lute? Also, they do add quite a bit of transparent amber color to the finish.

 

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You can get pretty deep shine with Tru-oil. Why don't yu do just that? Many mandolin makers do it. I think Tom Ellis is one ot the better known.

Or are oil products also non-vegan for your customer. (isn't crude oil/ petroleum also animal product?)

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