Renaissance Wax works ! for porous pipes ! (Microcrystaline wax) I just received some Renaissance Wax I bought off ebay ($25.00 for 7 ozs). I used it on my Savinelli Erica Fiamma 128 Billiard per directions and it worked well. Shined the pipe up and it is much cooler to the touch when smoking.
I bought it for my Barontini 1/2 spigot which has 3 areas of very porous briar along some fine line grain - too hot to touch even when smoking slowly. I mean scalding hot where you drop the pipe and burn your fingers because of the heat coming out of the pipe. The varnish had bubbled and I sanded the top of the pipe. The directions say to apply and wait 10-15 minutes then buff. That didn't work or didn't appear to work. I applied a second light coat and let the pipe sit overnight ... in the morning the wax had dried to the white haze described in directions. I buffed it by hand using a buffing pad for a drill. I smoked a bowl of 1/3rd bowl of Lane 1-Q smoked fast and hot --- the pipe got no warmer than any other pipe I have...in fact it only got slightly warm in those areas. It also seemed to lighten the briar a shade lighter but that may be an optical illusion.
So, it appears to work to seal in porous briar and prevent the bowl from getting too hot to touch. I definitely recommend it for any porous briar and wouldn't bother with the other waxes which are great for regular pipes but not great for really porous pipes (they melt off).
It is reputed to be the finest wax in the world and I believe it. Also it has a slight petroleum smell when applying but that dissipates and leaves no smell on the pipe.
I may do a post with some before and after pictures in a separate post. Buy some anyway as it can be used on almost any material (metal, wood, paint, cars, plastic, photos, cloth, etc.). It is also removable with mineral spirits without any damage to underlying material per pamphlet.