Jerry Lynn

Please don’t think I was suggesting that I Pooh-pooh’d anything. On the contrary, a large portion of selling nicer instruments is education, and providing comparison of like items in both past and current sales for pricing.

I find this thread amusing, and I’m sure I’ll regret my usual lurker status... it brings back lots of memories working for a larger firm where one of the most common questions asked in selling a violin was “is this hand made?” After getting into 20th century violins, the most honest answer I could give was “I have no idea.” Similarly, answers to questions like “is this an oil varnish?” Or, “did they have help making this?” With out first hand or historical sources proving one way or the other, you are left to judge the instrument on its own merits. My own experience with numerical controlled cutting technology comes from restoration work. From that I can tell you that it’s none of this as easy as people contributing to this thread would like you to believe. There’s substantially more head work to achieve extremely conservative results than the head work involved in doing things the old fashioned way. In 300 years our decendents will be arguing if the wood in the instrument was grown in a forest or printed on a cellulose printer.

Removing over varnish, or any sort of retouching, is never straight forward. Testing in inconspicuous areas, I generally try several different mechanical methods and solvents to see what is the most conservative approach to preserving the varnish and possibly texture below it. My "go to" method often ends up being scraping very slowly with a small curved scalpel blade (swann morton #15 being my favorite), checking often under UV light to make sure that i'm not accidentally encroaching on the original coatings. Another mechanical method is using an artist eraser. Occasionally soft over varnish, or over varnish that's been softened with solvents, can be pulled off in little balls with the use of a good quality white drafting eraser. Solvents are not straightforward, particularly with some shellacs that can become alcohol insoluble over time. Often, I find that Im using solvents, I need to alternate between them. (For instance, starting with alcohol followed by acetone, etc) Solvents can also be too aggressive, slowing them down with castor oil, and wiping away the oil residue with white spirit can sometimes be useful. There is no magic bullet, and often a job can mean using all the tricks. Good luck!

Woof. The danger of not doing anything with worm track is if the instrument gets dropped, takes a hit, or perhaps even squeezed too tightly the results can be really bad. Dealing with them is a mixed bag of pick your poison. The current thinking tends to bend towards using non-water based fillers. If the repair fails, the filler can be removed and replaced again. At least with open trenches. I've had good luck with a flexible two part epoxy called woodepox on open trenches on the inside of ribs. Externally, some commercial fillers work well, and with practice, you can retouch them effectively. Some also have good luck with scanning/cnc replacement of missing material. Closed track is much more problematic. The trend has been towards injecting them with various flexible epoxies. As you can imagine, there are difficulties with this...

There are two different versions of Fiebings. The "Pro" is a little more permanent than the normal stuff. Back at the firm we used to use it with reasonable success. There are still some players who's sweat will cause it to bleed. If you want to avoid it all together, black hair dye is the way to go. Takes a little more time, and costs more per board than Fiebings.

There are plenty of oil varnishes that are more than sensitive to alcohol. To make things more confusing there are coatings that were spirit that are now not very alcohol soluble.

I think it's tempting to want to go fast when cleaning something like this, and use one "magic bullet" for cleaning. I've learned from experience that sometimes layers like this are hiding, whether intentionally or unintentionally, surprises underneath them. Often it takes more than one cleaner (alternating), and sometimes mechanical cleaning, to get through heavy layers. So, I'd start with the least aggressive thing and work up to the most aggressive, all the while comparing under UV light and natural light.

What hide glue are you using (source)?

If you are incredibly lucky, the crack was glued with hide at some point before CA was used. In that lucky circumstance, the protein glue acts as an insulator for the CA, sometimes you can do a controlled moistening the area and “peel” strips of CA out. Usually this only happens with center joints that have been glued with CA. But, you never know. The above suggestion for commercial debonder is good. If it is too agressive, you can incorporate a small amount of acetone into laponite for a weaker version. Good Luck! Jerry/other jerry

Most likely the arch has relaxed on one side of the break (generally it’s a smaller piece that has broken off, or a flank split from end to F hole.). You will need some means of pushing the ends into alignment. A jig using small counter forms and wedges pushing against pins is useful for this.

"Compounding" is slang for using some sort of abrasive paste (something commercial such a no. 7 polishing compound, or a fine abrasive powder and a lubricant) to wear down a finish. It can be quite detrimental to texture. Dependent on the the Chinese manufacturer it might have some sort of polyurethane coating on it, which will bubble and separate from the layers below it. Regardless, to do an adequate job with enough precision to look great, the cost of doing such a job might render it not cost effective.

I’m thinking he should just go right to sand blasting.

Congratulations, Brad. I've been using an airbrush for a number of years now as a part of my work flow in retouching. I think the first thing to remember is that it's an augmentative tool, and not a replacement for the paint brush - 95% of the time is sits unused. The areas in which is really shines are neck heels after a reset, shading work that's been done with a brush, and clear coating. Neck heels and clear coating is where I get the vast majority of use out of mine. A few points worth considering: 1) Mask of anything you don't want spray to touch. 2)If you can help it, start outside the area to be sprayed and work your way into it. 3)The closer the nozzle is to the work, the more thin, intense, and most likely glossy the spray is. The farther back the more diffuse and dry the retouch will be. This can be helpful as a mating effect, shellac based retouching can go on very dry if you wish. 4) Pretty much anything that you can paint with a brush you can get it to go out of the nozzle. Dry pigments may need to be ground further dependent on your equipment. 5) Listen for "black balls of death." As the brush becomes clogged, airflow will be become spotty. Point the brush away from the area you are painting and allow large bits to evacuate the brush. Otherwise, black globs end up on your work. Not fun 6) Clean your brush thoroughly after use. After spraying color, or clear, I run solvent through the brush to clear out obvious remainders of material. You will need, or will be forced, to take the brush completely apart to clean it from time to time. Especially if putting it away for storage. Since I use mine relatively frequently, I store mine in alcohol. It's not the best thing for it, as it degrades the rubber O rings. But, it keeps it going enough that I don't have to tare it down often. 7)buy extra needles if you can. Stuck needles can get bent, they are impossible to straighten to 100%. I think that's all I can think of now... Good Luck!

I suppose it depends on the size of the area you are trying to fill... I've had the most success with taking small slivers using a super tiny high-sweep gouge and transferring them to the outside to a channel made with the same gouge. Any wood added to the outside over time has the tendency to become more visible and separate, collecting dirt and needing to be replaced by something larger. At least that's what I see with old instruments. There are of course exceptions. I think as a whole you'll find a lot more restorers using fill, or a fill capable of having shaving glued on top. When if fails they can be cleaned, and new put back in with minimal original material loss.

Hydrocal white is my preferred casting medium, mostly because I know how it "works." You can keep the surface of the cast easy to scrape by lining with cellophane and filling with sand while it cures over the course of several days. This keeps a hard calcified layer from forming on the top. Be sure to elevate the cast off of the table to allow adequate air flow underneath, so that moisture can escape, and the cast can cure. I am currently trying to get more familiar with tecstone. I think with any new medium for casting there is a learning curve, and a comfort factor... you shouldn't expect success on the first pour. Like Jeff, I also use rigid closed cell insulation for cast forms. If you use open cell foam (styrofoam) for a cast form, you're going to be in trouble trying to free the cast from the form. If this is the only foam you have at your disposal, you can line the form with packing tape. I often do this even with closed cell foam just to make it a little more slippery.