I've said it once and I'll say it again. If you put a thin coat of washed linseed oil on your white violin and leave it in the sun for a long time (this is where your patience has to take command), you will end-up with a violin that has a natural, golden color and you can then put a pore filler on the wood ( I use a high quality shellac ). Once that's dry (don't sand the pore filler), I start putting on layers of color. Every time I started using shellac as my ground coat, I've never had it fail when I start putting oil varnish on the instrument.