Refinishing problem

[PeteM]

I’m refinishing and old (not antique) desk. The top is a nice, reasonably thick, mahogany veneer. The problem is that it was grain filled with white filler before it was sprayed with the usual thick toners to cover up that nice veneer.
I’ve stripped and sanded it but the white filler remains in the grain. I’ve tried applying stain and spraying a light coat of toner but nothing seems to stick to the white filler. I also tried removing it with a soft brass brush and some mineral spirits and lacquer thinner. Neither had any noticeable effect.
Any ideas how to “get the white out” or am I stuck with white specks in my desk top???
pete

 

[pslamp32]

Will shellac stick to it? Shellac toned with Transtint works great...

 

[Tarhead]

May also try Transtint on it first before the tinted shellac. The factory probably followed a dye/toner/glaze/sealer schedule.