Soft oil varnish - how do you...
As already mentioned earlier, I happen to own a fine viola with rather soft varnish and as I'm playing without SR, it's a bit of a struggle. Now I added a violin of similar characteristics, and although its not 13 years but 52 years, the varnish still lacks what I'd call "completely cured". It just sticks to my t-shirt! When I add a piece of chamois, it will stick to that. Best works a piece of microfiber, but it's too slippery. From my viola I know it's not a big deal to have these marks polished out once in a year, but... it sucks.
Go to maestronet this is where Luthiers hang out. If the varnish (obviously oil based) is to ever cure it will need a lot of UV light exposure. Some oil varnish will still be soft after centuries! Makers use UV light boxes nowadays to speed up the curing process, and if it were me that is what I'd be looking for. There may be some chemical treatments possible (and likely risky), but only a luthier could advise you on that and in any case would have to be done by a professional, hence maestronet. 52 years and still this soft make me wonder how there's any varnish left! My instrument (brand new at the time) had very soft uncured varnish, and the UV box made a significant improvement in both hardness and tone, but it wasn't 52yrs old though (the varnish that is, the wood is however 70yrs old since harvest).
I don't think I'd buy a violin where the varnish felt sticky.
I am currently varnishing a guitar with a very simple oil varnish. After one day in direct sun, any parts exposed to the light will be completely dry and hard enough to sand. Presumably your violin has had more than its share of UV exposure over its long life... the varnish still being soft is simply unacceptable.
Oh no, this can last for centuries?? I happen to have such a violin, which is just 5 years old. I have a piece of leather at the bottom, and that sticked, and the varnish got marks. It got polished, last year, but now, I am at the same point, again.
57 years ago I had in my hands a 250 year old Stradivarius violin. When I handed it back to the owner my fingerprints were still embossed in the surface. They vanished in a minute or so.
My go-to varnish for home woodworking projects is Minwax Helmsman for an oil-based varnish and Benwood Stays Clear for a water-based product. I've never had these issues with these fine products.
If the varnish has not dried by now, UV will do nothing more than bleach the color. One way to possibly solve the problem is a coat of [only!] orange shellac. I can't guarantee this will work, however, and I would try it on a violin I did not make myself. I would contact the maker for his advice.
Strange that you have two fine instruments that you like with varnish that has not set properly. An unset overly elastic varnish can heavily damp the tone - perhaps your ear is attracted to that? I'd take the instrument to a luthier to have it revarnished with a proper setting varnish. Any competent maker would do that for you.
I purchased a new instrument that had the same issue. A suspension case left impressions at the top and bottom. Eventually, I got it back to the maker, who polished it out a bit. But it won't look new ever again.
I think my description of the situation was a bit unprecise, so I'll try to go into detail...
Nuuska, congrats on your acquisitions. The instruments sound beautiful but a tiny bit temperamental regarding the varnish issues. I would use a SR. Have you tried the VLM Diamond? It’s very light and will allow you to get the violin up close. At least it works for me. Best of luck!
I double the suggestion of French polishing with shellac. This serves no other purpose than concealing the stickiness with another resin.
John, it is the VLM I finally ended up with after acquiring a representative collection of different brands and models... For me it works because it goes down low and can be angled towards the collarbone, but that's a different story.