The subject of violin varnish has likely been exhausted so please excuse this question. I know it will sound simplistic to many of the experienced luthiers who visit this site.
In my experience there are two kinds of mineral spirt varnish used mostly on furniture these days: polyurethane varnish and the so called rock hard variety (Behr Rockhard). I’m not going to mention those horrible water soluble kinds seen in the chain stores these days.
The major difference between these two is hardness of the finish. Polyurethane is relatively soft and cannot be polished with fine abrasives after application so one must decide on gloss or semi-gloss appearance by choosing the product prior to use. The rock hard variety does allow post application polishing with abrasives that give variable luster depending on what is used (pumice or rotten stone).
Are either of these suitable for violins?
I know one can spent $100 or more for a few ounces of violin varnish, but a fiddle mechanic like myself just can’t justify spending that kind of money on the fiddles I putter around with, mostly for my own use.
I see lots of varnishes here http://www.internationalviolin.com/Shop/varnish-supplies for alot less than $100.
I understand though that there's more to finishing a violin than just the varnish.
Varnish is a subject that you can make a simple or complicated as you want. Look on Joe Roberson's website for a good place to start. You can go spirit or oil but I would do a lot of testing and practice before doing it for real. It is usually a three or four step process from ground to,color, finish and compounding.
I would go with a no to the two types you mentioned. Get some violin varnish or violin shellac from a reputable seller. Although I have a fiddle that was finished with marine spar varnish that sounds pretty good....
Stay away from both of those!!! Some people (me included) have had some success using oil based spar varnishes. Specifically, the Ace Hardware Oil/Solvent Spar varnish. This is no longer stocked in the quart size(gallons are available), but you may be able to find some somewhere. There may be other oil based spar varnishes around, but stay away from polyurethane.
Note!!! These would be for use on New wood only! If you're working on old fiddles, spirit varnishes are used for touch ups. It's generally considered stripping and re-varnishing old fiddles to be a VERY bad idea.
Edited by - FiddleDoug on 04/20/2017 03:33:56
The last couple of comments are interesting. Both seem to say don't use hardware store stuff, but then...
The fiddle I'm currently working on was non-professionally re-varnished sometime in the past.. It was left slightly roughened and uneven with a finely bubbled surface.
I'm hoping to smooth this off with 600/800 grit paper, used either wet or dry, then apply one or two coats of something that can be polished to low luster, but still retain the appearance of an old fiddle.
Does this seem reasonable?
Edited by - RichJ on 04/20/2017 05:26:02
From outside the box...I'm probably swimming up-stream on this, but just to provide a counterpoint...I think fiddles produce better volume and tone with as little varnish as possible. In fact, I think they sound best with no varnish at all and I have seen published material that supports this (e.g. Bruce Ossman's book Violin Making). Varnish basically serves two purposes, first to protect the wood and secondly to provide a nice shiny finish for clientele who pay a lot of money for these things and expect them to look new. It succeeds with both only marginally, look at any old fiddle (dings, cracks, darkened varnish, re-varnished, lost varnish, etc). While it initially succeeds in making the finished instrument attractive (again time will have its way...), the wood--particularly the belly plate--must physically move to produce both tone and volume. Virtually any varnish that is applied to the surface stiffens the wood by way of tension and this is why luthiers have traditionally preferred soft varnish. Historically the trick with tone wood varnish is to produce an attractive finish that has the least effect on volume and tone. My personal preference (feel free to politely disagree but please hold off on the ALL CAPS and flames) is to varnish the hard maple back plate in any way you find attractive (the back plate is generally not supposed to move with the sound, but to reflect it), then put only a light coat or two of oil on the belly plate to bring out a bit of natural color. OMG, Strad is turning in his grave...
Anyone ever used this?
Looks like a spirit varnish which should be good for touch up.
Coloring requires aniline dyes which are alcohol/water soluble and also carcinogenic.
Edited by - RichJ on 04/20/2017 08:54:58
I have been using Zinsser Bullseye Shellac and like the results for repairs. It is alcohol based and dries nice and hard. It is easy to touch up. I have added analine dyes filtered through a cloth to top coat and match existing colorations. It is a hot finish that will dissolve previously applied coats, so you coat and move on. If you have ever french polished, you know that you work quickly and move on. But touch ups are easy. And I like the results.
I've used it (Behlens). It's OK for that. There are also natural color extracts that you can use with it.
Edited by - FiddleDoug on 04/20/2017 10:09:04
I use Tru Oil on new instruments, and have used other linseed oil-based products before. It works quite well for me, and I do not attempt to color instruments because I am colorblind and can't tell what I'm doing very well. I like to let the wood be whatever color it naturally is.
Best to think of a finishing system and technique. Materials are likely to be less important in many aspects.
Bare wood sounds pretty good. A proper ground can make sound better. Dirty bare wood sounds horrible.
Most people don't bother with treatment/primer. Borax and many other treatments exist. I expect they do little harm. Some will deepen the tap sound, but no idea whether that really carries through.
Sealers are many. Nagyvary reported plant gums. Some research suggests oil varnish. Or various other things. Vernice bianca referenced often. I know top maker who uses casein. Shellac seems fine. Straight gum arabic seems fine. Gum arabic changes the tap tone a bit to the more focused. YMMV. No idea whether this carries through.
So now there's wood with treatment / sealing. One of the important things that should do is make the figure pop out. The other is to keep the ground from penetrating too far. UV tanning or something to slightly darken the wood and pop the grain. Various solutions available.
Ground is the most important. I suspect the casein acts as a ground and sealer. Pretty cool stuff. I use a mineral ground. Currently aerosil, which was superior in my trials to the Rubio ground, pumice, rotten stone, fine ground glass, and probably other things. I've always wanted to use nano-diamond. Vehicles for putting in that I have seen used are mostly oil varnish, but I've seen other varnishes, the organic sealer mix, and just a rub in and seal with shellac used.
Now the violin sounds better if strung up. More power and focus. So I would concentrate on the ground. This site discusses: http://www.rubioviolins.com/ I would not use that system, but it's a system. Too aggressive a sound for my liking. YMMV.
Color. I have seen people put tea walnut dye etc directly into the wood. Often some mellow yellow in the ground. The Rubio ground is a bit yellow itself. First color coat on the old work seems often to have been a layer of strong red. Delicate to work with. Regardless, transtint dyes are good. Oil color or direct pigment often mulled in. Or a glaze is easy with a bit of practice. 100 fiddles should get your technique down! Rubio site has glazing as well. Need fine particles of right optical match, thin layer, or things will be muddy. I used to take off almost all the color layer - down to a firm wipe. Just a tiny thickness of particles in vehicle. So a strong color is required. Think of this as transparent painting. This was done in the old days. I've seen old fiddles with wipe marks, fingerprints etc., even some good ones. Not that it was always done, just one of the techniques was clearly by hand application.
Varnish. I would not use the plastic varnish. The old Ace oil spar worked fine. Not so convinced on the new. The Howard Core or International Violin supplied cooked varnishes are good. Various spirit varnish recipes are good. I wouldn't use straight shellac. Forever build. I've used Darnton mastic varnish, which is very authentic. The stuff has a hard time ever really drying, takes imprints, is a pain to take care of, and wears off. Just like the original. Will not use again, but might experiment sometime. Here's a tru-oil article. http://www.mikeouds.com/messageboard/viewthread.php?tid=12156 Fun stuff. I have done similar finishes with polymerized tung oil with good success, before I found that nice thread. Thin seems the way to go, which takes strong color.
I expect that the nicest final result comes from the preparation of the wood to just right show figure, sealer that doesn't screw that up, a non-penetrating ground that tightened up and focuses the sound as well as armoring the wood a bit, then concentrated thin layers of strong color, possibly near primary in different shades. I have a reddish violin now I want to cool down, and I'm considering whether a layer of pure ultramarine might not do it. Could turn it purple in some light and at angles, and reddish with just a tinge of purple direct on. I've done that before, and still have a surprisingly purple violin from 15 years ago that I made. Doesn't look purple except in the right light.
My recommendation is to seal and ground, then use commercial oil or maybe tru-oil.
Now I'm excited and will pull out my polymerized tung oil, whip something lush up!!
OP, in part, inspired me to try making an easy brush or wipe on/wipe off varnish that kicks off pretty fast. Something that starts to set quickly before it runs, but can be brushed for a while, and will also allow final thin layers by rub on/wipe off (gets a really smooth finish). I have something, but it's only good for mixing and using. Proportions not particularly important, but good materials are:
Well before hand: mastic in real turpentine, let sit a few days. I just keep mastic in turpentine all the time, and add one or the other. Shake it whenever I go by.
1 part polymerized tung oil (probably not required, but dries pretty fast and is a hard oil)
2 parts really nice linseed oil, pure, the real thing
3 parts whatever oil varnish you're using, so long as it will run into the first two components. I imagine even the modern "oil" and "spar" varnishes will work, maybe better because I suspect those are mostly resin & solvent mixes, rather than cooked. Who knows on that one!
1 part or more the mastic/turpentine. Mastic is a drier and keeps the varnish supple. Probably helps layer to layer adhesion, too.
Whatever color you want, pretty strong to get a tint in the thin. I haven't tried pigment suspensions, but I imagine they'd be fine. Have to go quickly - this stuff kicks pretty quick once thinned out by brushing.
Will set in the jar!! I am just using from a big glass mortar. Mix enough for 4 coats and apply, adding turpentine to keep at consistency for brushing. Wipe on consistency is a bit more thinned. Cleanup right away or forget it, will keep things sticky.
The mastic / linseed oil / tung oil will set and gradually polymerize on its own. The oil varnish component seems to kick more quickly than usual. UV kicks it fast. I imagine a drop of cobalt drier would give a 24 hour set to hard. If you're a good fast worker - careful with driers. I prefer not to have them on violins, but other stuff, sure!!
Now if you want to experiment, just find resins that will dissolve in turpentine. Dissolve them. Then mix the turpentine mixture with good linseed oil and brush on. Mastic in there will help the setting a good deal. There are likely other oils (e.g., Tung) that will do as well.
Distinguish turpentine ($$$) from "turps" at home depot!! Distinguish linseed oil ($$$) from garbage health food oil.