Replies

1. 
   SteveSchoene | Mar 17, 2009 11:24pm | #1

   It may or may not be lacquer.  Finishes for stringed intruments is a very arcane art, with many different formulae being used, especially since the finish can affect the tone, and presumably the value to a significant degree.  I'd consult a professional.   There may well be luthiers hanging about on knots.  Lets hope one happens along. 

1. 
   Skally123 | Mar 18, 2009 12:04am | #2

   Thank you for your response. Luthier is a new word to me. What is a luthier?
   Paul

1. 
   SteveSchoene | Mar 18, 2009 12:19am | #3

   Someone who repairs or makes stringed instruments. 

2. 
   Rich14 | Mar 18, 2009 03:01am | #4

   Paul,As Steve explained, a luthier is a person who makes or repairs stringed instruments. And the process of designing, building and repairing them is called lutherie.Depending on the age and origin of your cello, the finish could be shellac, lacquer or oil-based varnish. In fact, among violin makers ALL those finishes are frequently called "varnish."I can't claim to be a luthier as I haven't made enough guitars (yet). But I've repaired and refinished many guitars, a few violins and one cello. Contrary to popular belief, the finish does not affect the tone of these instruments very much. Better stated, a properly-applied finish does not have much effect on the tone of the instrument. If your concern is that the cracked finish is causing any problem with the instrument's sound, you needn't worry. And a cracked or crazed finish is considered ordinary aging by many.No offense intended, but since you've asked this question, you don't have the experience you need to tackle this job. My best advice is to look up violin repair, instrument repair or luthiers in the Yellow Pages and get the instrument professionally done.Gaining basic finishing experience on an actual instrument is not the way to go, (even "inexpensive" cellos start at several thousand dollars in my experience), but here is the information you've asked for.The type of finish can be determined by sequentially applying alcohol (shellac solvent), or lacquer thinner/solvent to an "inconspicuous" place on the back. First wipe the instrument with mineral spirits (paint thinner). This won't dissolve shellac, lacquer or varnish, but will clean the surface by removing any wax, skin oils or other dirt. Such grime would also lift with alcohol or lacquer thinner, confusing the results. You might conclude that the residue appearing on the rag is finish when it's just dirt.Any "hardware store" lacquer thinner will do.But you must be especially careful in selection of denatured alcohol (DNA). DNA is made by adding various chemicals to ethyl alcohol, rendering it non-drinkable (poisonous). Use only DNA denatured by the addition of Methyl Alcohol ("wood alcohol"). Some DNA is ethyl and other alcohols, denatured by the addition of ketones, making the mixture a lacquer solvent as well as a shellac solvent. I found this out the hard way when I used DNA from Home Depot to clean a guitar that had a lacquer finish. I had done such cleaning many times previously (alcohol dissolves skin oil faster than mineral spirits). But my "old trusty" DNA contained methyl alcohol as the denaturing agent. The DNA from Home Depot had ketones in it and it took the lacquer right off the wood before I realized what was happening. A simple cleaning exercise turned into a complete refinishing job.The only way I was able to determine the contents of that DNA was by getting the MSDS from the manufacturer's Web site. So before using DNA, either check the ingredients (if they are listed on the can) or get the MSDS.(You can also use "reagent grade" ethyl alcohol, but that's very expensive, available only from chemical supply houses, and likely to require you to have a license for the stuff)Carefully apply either denatured alcohol or lacquer thinner by daubing a small spot with the corner of a slightly damp rag. Here's the logic:Use DNA1. Finish comes off on rag, finish is shellac. Stop.Or2. No finish comes off on rag, finish is either lacquer or varnish.Use lacquer thinner3. Finish come off on rag, finish is lacquer. Stop.Or4. No finish comes off on rag, finish is varnish. Stop.Once you've gone through this test we can describe methods of repairing your finish. But I hope you don't go this far!Good luck,Rich

1. 
   Skally123 | Mar 18, 2009 06:35pm | #7

   Thanks Rich, for your extensive email full of knowledge. As, I said, it is a "show piece" in the living room and my wife hasn't played it for over 20 years and probably never will again. It was a high school and college interested of hers and she is now a university professor and doesn't have time nor interest to play again.Having said that, it doesn't mean I am going to "destroy" its future use by someone who will some day enjoy it. So thanks for the very valuable information on finishing, especially the info on the different DNA. Very valuable information. With your and others advice, I will put this project away, not on hold, and proceed past jail to tackle my next project which may be refinishing all the kitchen cabinets. ARG!
   Again, thank you.
   PaulPS. Better yet, spring is here.... I think I'll go fishing.

2. 
   calden | Mar 20, 2009 05:15pm | #10

   Rich:Nice summary of how to deal with finishes on instruments. It's also good to hear someone talk about denatured alcohol. I do french polishing and have a license to buy Everclear, which is the best to use with shellac.Carlos

2. 
   PeteBradley | Mar 18, 2009 04:17am | #5

   As others have said, this is one for the pros. Even pretty basic instruments have gone up greatly in price lately and it's the kind of thing that could easily be messed up. I suspect if you just look up luthiers in your area, you'll find a lot of guitar guys and hacks. A better approach is to call the music department at your local college or the strings department of a music college in your area and ask who they use for violin/stringed instrument repair.

   Pete

3. 
   Gretchen | Mar 18, 2009 02:00pm | #6

   As others have said, this is not a job for anyone but a pro. The finish on a musical instrument is an integral part of its tonality.  It may not even need refiinishing.

   Gretchen
4. 
   pzaxtl | Mar 19, 2009 07:18am | #8

   In addition to what has already been said, if the instrument is vintage you may very well destroy it's value by refinishing it.

1. 
   Skally123 | Mar 19, 2009 09:57pm | #9

   It is 50-60 years old, so I don't know if that is vintage age. Thanks, Paul