back to the question of popping the grain: for what its worth, this is the process I've used on furniture in attempting to pop the meduliar rays on quarter sawn white oak: after raising the grain with water and sanding smooth, apply the transtint dye and sand smooth again. Next step is a coat of shellac and again after dried, sand smooth. The next step is where the grain has really, really popped: a coat of gel stain. And after that, the top coats. I've not used this on walnut, but I know it works well on curly maple as well.
