It sounds like this Asphaltum would fill the pores in walnut, is that the case? Gary
Not sure I'd want to use it on walnut, and I don't think it's stiff enough to fill the pores. Although it's thick, it rubs right in. I think walnut (personally) is at its best with a clearer finish - filled pores are great, but I've never felt the need to darken it up. This stuff is dark - I rubbed some on a walnut blank today and it was very dark. It'd wind up being - I'm afraid - a big mess.
Incidentally, I put some BLO on the piece I tested (on maple) and couldn't tell that it darkened it at all, which was a strange thing. I'm used to oils and varnishes darkening whatever is there, but not with this.
Here's a photo of some on a piece of scrap. The photo makes it look much duller than real life - it's actually quite glossy.
I keep waiting for Flintriflesmith to chime in...