Sandarac Finish
Advice on applying sandarac finishes to musical instruments, as an alternative to Tung oil or shellac. August 8, 2008
Question
I make small bagpipes called smallpipes and Border Pipes. I love using boxwood and Ivory palm nut on the ornamental bits. I've used a variety of finishes to try to keep the boxwood clean, with varying results. Some of the pieces are touched often. Most of my training involves using woods that need no finishing, and synthetic materials that also need no finishing. But I'm trying to get away from synthetic materials and I'm also experimenting with non-traditional woods for bagpipes. So I need the best finish that will allow the light colored wood to look beautiful, but not pick up dirt from fingers. These are round pieces turned on the lathe. Applying the finish on the lathe would be a plus.
Forum Responses
(Finishing Forum)
From contributor A:
Sandrac resin can be applied as shellac as a friction polish. Most people are not aware that the first polishes used by the French were of this material, not shellac. Temper the Sandrac with oil of lavender or pure castor oil crystal grade 1/2 percent per volume by weight of resin. A 1 to 1-1/2 lb cut is normal for use.
From contributor B:
Does the Sandrac offer an advantage over shellac?
From contributor A:
Sandrac offers increased hardness, non-yellowing, almost as clear as acrylic. It friction polishes well, has a long history like shellac as to wear and tear, and as stated it was the original preferred friction polish for French works of Louis the XIV furniture. It has as good or better wear, is not as permeable or affected by skin oils. It is a main ingredient in many violin varnishes along with other resins.
From contributor B:
I'd actually heard of it before, but I've never run into anyone that had actually used it. Is it as easy to use as shellac? Other than availability, are there any downsides?
From contributor A:
One downside is that it is more brittle than shellac so you need the oils suggested to plasticize. Sandrac is alcohol soluble like shellac. Use anhydrous 200%, not store denatured. Straining the material before using with medium filter and buchner funnel with vacuum is best but normal will suffice. Weigh the resin before solving, and then add the oil to the resin weight at 1% mix and let set overnight. Mix again, and then use. You can brush, use cheesecloth or - my favorite - friction polish. It can be applied while the piece is on the lathe at slow speed. It builds pretty quickly so be careful not to put too much on at a time. Let dry a few hours and reapply.
From contributor C:
Have you tried a tung oil? It's easily applied while your instruments are being turned. A few coats of oil applied in this fashion will yield a beautiful finish. Another finish to consider is beeswax. You might be surprised at how fast a build-up you can achieve.
From the original questioner:
I have ordered some Sandarac to test (along with the oil). I will let you know how it turns out. As for tung oil, is normal hardware grade good enough for this?
From contributor C:
I'm not so sure what is meant by "normal hardware grade" but if you can get some Southerland Welles tung oil you will be quite happy. For the first or second coat, I like to dip some sand paper into the oil (320) and burnish it into the piece while it's rotating on the lathe. Caution - the finish will come out extremely smooth once you've built up 4-5 coats so be careful the instrument doesn't slip out of your or your customer's hands.
From the original questioner:
Sutherland Welles seems to have a large line of products. Is there one in particular I should try? With tung oil, do I need to wait 24 hours before adding the next coat? That might make using it unfeasible.
From contributor C:
If you are applying it to a large surface like a table top, that might be the case. You however are going to be applying it to a small piece of wood moving at a high RPM. You are also sanding it into the wood, and that speeds up the building up process. I might suggest you try applying some regular Watco oil to a sample piece of wood. Apply it while the sample piece of wood is spinning on the lathe. Dip some sandpaper into the Watco and apply it to the spinning piece of sample wood. If you are happy with the results the regular Watco gives you, you will be happier with the results you will get with the tung oil. Make up some samples in your spare time and judge for yourself. Oil finishes do take time to complete compared to solvent types, however the end results are awesome.
From the original questioner:
There is a hardware store nearby that carries the Sutherland Welles tung oil. I'll go pick some up tomorrow. I work at home, so "spare time" is kind of a joke. But I'll give tung oil a try. Something like 3-4 coats? Can you do them all in one sitting? I've never used an oil finish on the lathe.
