I am awaiting delivery of a second-hand Big Muddy mandolin, which, in conversations with the maker, I have learned is finished with French-polished shellac.
As I have never owned a shellac-finished instrument before, I am wondering a couple of things: First, how durable is the finish? I'm pretty sure I don't want to get any water on it, but is there anything else to look out for?
I'm also wondering if there is a safe way to add a subtle sunburst effect to the top, using colored shellac, or if I should just get that idea out of my head altogether and let well enough alone.
No alcohol or acetone on Shellac. You can use a microfibercloth. A good way to add a sunburst would be to spray a sunburst with tinted shellac, then clear sprayed shellac coats. As far as I know, you can't make a sunburst using french polishing and shellac.
Thank you. One more question: does a shellac finish darken over time, like a nitro lacquer finish?
The benefit of a french polish is in the surface, cover it with anything and it is basically gone. So please, no sunburst.
Shellac won't be hurt be anything you *want* to have on your musical instrument :-)
One more thing to remember is that shellac is more prone to scratching. It's also easier to fix but the the instrument should be handled a bit more carefully.
I think it yellows with time and exposure but if you want to change the tint it's fairly easy to do. Besides tinting with dyes, there are different types of Shellac that have different properties including color.
Not to contradict Pierre-Antoine but I think it would be possible to do a burst by hand because of the way the finish builds one very thin layer at a time. That said, spraying is the only way I've tried to do it. I'm not anything like an expert but I've had some pretty decent results in repairing sunburst with tinted shellac through an air brush. I've found that I must use a much higher ration of alcohol with the shellac than I would with French polish or it will go on dry. Once you have the burst like you want it you can FP over it but you should be pretty careful to begin with because the alcohol can soften the sunburst layers and pull it around a bit. In other words, make sure to get some build with the clear shellac over the sunburst before you go to town with pressure on the FP.
Don't be afraid to contradict Ned! I've heard that some do bursts using french polishing but with alcohol dies on bare wood. I didn't think it was possible by french polishing shellac. Anyone using that technique?
As I said, Pierre, I haven't actually tried it by hand. I just know that shellac builds such thin layers that it seem to me that it should be possible. I've also never tried to do a sun burst on bare wood. I don't particularly like putting stain directly on the wood. I spent too many of my teen years staining cabinets for my father to not understand just how variable a stain can be on a piece of wood.
I do have a low end mandolin that I will get around to repairing some day. I may try it on that just see if it's possible.
Best place I found for excellent shellac is; www.shellac.net Various "colors" too !
Just remember that if you do try a sunburst using shellac you won't be able to get a high gloss finish without french polishing the surface.
What this means is, if you don't know how to french polish you will never get the gloss surface you are looking for.
Shellac won't generally take a "polish' by conventional means such as rubbing compound or automotive polishes.
You CAN , however, apply lacquer over the shellac. (prep surface as you would normally for lacquer)
I am in NO WAY suggesting that you do this, but if it were me and I wanted a sunburst finish on this Mando, I would do it in lacquer