A friend was recently given a nice looking violin, a German Strad copy, which looks to be in virtually unused condition except for a short, 1/4" hairline crack radiating from the bottom of the bass f-hole towards the butt. It's all the way through but closed and not displaced. It's probably from a previous period of dryness here in the Arizona desert. What's the best way to fix it? I'm thinking of just floating a little hot hide glue in the crack while it's warm. I'm not sure it even will need finish touchup. The finish is a darker brown but I'm not sure whether it's varnish or lacquer although I suspect the former. It's 4/4 size, probably a student model. What think ye?
I say get the hide glue in and maybe a cleat. Sounds like varnish to me.
Hot hide glue rubbed into the crack is the way to go. Shouldn’t need a cleat. Clean off any glue ooze inside.
shouldn’t require any finish touch up.
Hot hide glue is practically mandatory on violin repairs. The violin restoration and conservation industry has a 300+ year old set of traditions. I find the methods they use to be based on observation of how well different types of 100+ year old repairs have held up. For instance, they would not approve of now many of us shape the cleats we use to repair cracks. They also seem to spare no expense. There are several classic violin repair texts (Hans Weisshair) and much information readily available. The routines they use for touch up are also quite sophisticated, since they deal with an endless variety of finishes and colors. To read about violin repair, do a google search for your topic and maestronet ("crack repair maestronet") and read to your hearts content.
You can learn a lot from the violin restoration and conservation industry. Many methods are simply the best one to use even with guitars. That said, a violin is very small compared to a guitar. The weigh of one cleat can actually change the tone in a violin, not so much on a guitar. So, guitar repairmen like me don't have to got to the same extremes as a violin repairman.
Actually the shape of cleats can force the cracks open or even create new cracks, the shape, not the thickness is one of the issue.
I know that cleats on a violin should be made like an inlay, as much wood as the cleat is cut away from the top and the cleat is fitted snug into the cut out. Naturally glued with HHG. Just to maintain the exact weight before and after.
As for the shape, I have heard that there is at least two schools for how the angle of the grain in the cleat should be over the crack, 90 or 45 degrees. I think it's the German and Italian way, both sides think they are right ;-)
Never seen or heard of cleats being inlayed into the wood. It would be impossible to inlay over a crack without disassembling the instrument. Also never noticed cleats effecting tone or volume, even on a violin.
I know there are some violin repairmen that have strange ideas about things that make no sense at all to me.