Has anyone used a Alkaline type dye or dyes used in Luthier projects

Good Wraps Bob

I've never found anything that will dye cork evenly and deeply. It has always come out 'blotchy" and just a slight sanding deep.

i don't believe it is the type of dye that is the problem. it is the cork itself. the only thing that might work is to use a vacuum or pressure to help the dye into the cork. even then i dont think it will penetrate much further than the surface. if you have a pressure pot or vacuum you might try it and let us know the results.
i believe the colored composite corks have the dye added when they make the composite and that is the reason it is colored throughout. if you look at them closeley you can see the dye doesn not penetrate the cork, but is in the strata around the cork pieces.
if you try it let us know your results. i tried to dye some birch bark once and had the same issues, but didn't try to vacuum or pressure.

With all the playing I have done with cork.

A tint in a thin mixture of finish whipped on the cork will color but not completely cover it.

let dry - then one or two coats of a finish you like

That is about all you can do - with cork But it does look pretty !!

Bill - willierods.com

Cork is a closed cell material and as such will NOT absorb liquids including dyes whether under pressure or not,!. Any type of liquid remains almost exclusively on the surface

Composite colored cork has the color in the adhesive used to bind the pieces as JP stated above.

I've had good success using Minwax exterior stain on composite or burl type cork handles. It doesn't get any deeper but it does hold up very well since the material is tougher.
Although this doesn't answer the original question...

Bill, won't a thin coat of finish crack or peel over a flexible material like cork??

I have tried canning, using almost straight dyes. The results were all the same blotchy surface stain that buffs off. One of these days I will run into something and make a million LOL thanks Guys

Good Wraps Bob

Rick

I after shaping the cork , clean it well. Then mixing the finish and thinning whip it on even with a paper towel . It does sink in, if even just a little adheres and seals as well With a tint in it it will adhere to the cork.
It will stiffen the cork but is very flexible.

Try it on a scrap piece.

Bill - willierods.com