Replies

1. 
   SgianDubh | Dec 07, 2002 08:36pm | #1

   Certain shellac types are safe to go under any film finish, such as oil varnish, water based varnish, and the nitrocellulose family of lacquers, such as pre-catalysed, and post catalysed type.

   Dewaxed shellac specifically is safe for this purpose-- you can de-wax your own if you you dissolve the flakes yourself, by letting the liquid settle into layers and separating them. Or you can buy dewaxed flakes, and lastly, there is a product called SealCoat made by Zinnser in the US which is a ready to use dewaxed in a can designed specifically for the purpose of sealing the grain and creating a barrier coat. This stuff can aslso be used as a polish in its own right.

   Typically, but not exclusively, a shellac barrier coat might be used where you perceive there might be an adhesion problem between the polish you desire to finish with and the timber-- examples are applying a water borne varnish (or even an oil borne varnish) over oily timbers such as teak, or a refinishing job where you are suspicious that silicone or other contaminants might be present, or you wish to polish or paint a resinous timber such as many pines, particularly around knots, and the like.

   As such, creating a barrier with shellac will prevent true oil finishes, such as tung oil, or boiled linseed oil from penetrating-- if that was your specific question.

   There are other uses for shellac which I'll avoid going into much as the uses are unrelated to your question, but briefly, in one use in thinned out form shellac can be used to help in some of the timber staining, dying, grain filling, and polish tinting processes often used by furniture polishers. Slainte.

   Some stuff I've made.
1. 
   dwsouthwick | Dec 27, 2002 04:56am | #2

   Thanks for the information. I took a look at the items you have built and I recognized one right away. That bed you designed and built for the Woodwork Magazine, very impressive. Thank you for sharing your expertise online and in the magazine, it really helps those of us that aspire to such projects.

   ds

1. 
   SgianDubh | Dec 29, 2002 03:23am | #3

   My pleasure ds. Always happy to help if I can--- well, except for when I'm playing the fool and trying to get a rise out of someone, ha, ha.  Slainte.Some stuff I've made.