I restore a lot of classical guitars and find myself french polishing a lot. I have read in old books about adding tree resins and ox gall to make the shellac more durable. As of now I use the standard shellac/190proof mix & elbow grease. Have you had any experience with additives and shellac. Click the link for more pics.
Very nice looking FP jobs there!
There is a company in OZ that makes U-Beaut Hard Shellac which has additives to supposedly make it more flexible and tougher at the same time. I've never used this product but I have owned it before deciding not to use it because when the manufacturer came on another forum that I participate with he was less than forthcoming as to what the additives are. I understood in advance the need to keep proprietary info just that, proprietary but when I amended my question to simply ask if there is anything more toxic in this stuff than what's in regular shellac I received no answer.... Part of the beauty of using shellac to me is the lack of toxic substances and my ability to use it pretty much anyplace.
The first iteration of this product caused some crazing on instruments that it was used on so at present we are on the second iteration. The company has a forum I believe and you may be able to find some tips on shellac additives on their forum since who participates on this forum are folks looking for shellac like performance but with more toughness. Google the product name and that will take you to the manufacture and their site as well.
Regardless though I'm not keen to believe that with additives shellac would be much tougher than it is as is. It's an excellent seal coat and even pretty water resistant for a spell contrary to popular belief but as far as being a tough, resistant ding barrier like a polyester finish is this will never be one of shellac's attributes.
Also check out www.shellacfinishes.biz in so much as this man, Vijay, is a great source for not only "fresh" shellac but shellac info as well
I thought about the U-Beaut Hard Shellac but chose not to use it for the same reasons. I work with mostly fine classicals and the last thing I want to do is use a product that is not reversible. Thanks!
A standard additive that I have always used is gum sandarac. My usual mix is 1 part by weight sandarac, 10 parts shellac flake, 100 parts alcohol.
I mixed some gum Arabic but found it did not go on as smoothly. I will try your mixture! What I have been doing is after the shellac has gassed out for a few weeks I apply many coats of pure carnauba and or bees wax, I find that the players burn through the wax and not the shellac. Pure wax is a natural and does not affect the shellac or tone.