No soot is all!
I mixed my lube in a pan on a hot plate. I know you're supposed to use a double boiler. I didn't.

I also tried the pan version with an 1/8" thick sheet, lifted from the pan after it cooled, then pressed the sheet of lube over case mouth after seating the wax-wad with 1/10" powder compression.

Prior to using the flat sheet of lube version, I used a screw-driver tip into a lube cake to get roughly the same amount of lube, then rolled that into a ball & pressed that into the case & onto the wax wad over the slightly compressed powder.
That worked.
I used a wax paper disk/wad between the powder and lube ball, to allow the powder's flame access to the lube ball with appears to help it coat the bore to keep the fouling soft. This was written up by the late Paul Mathews in his book "The Paper Jacket". An excellent book to have.
I have been doing this since reading this book, as well as with BP loads and paper patched bullets, having the patched bullet barely over bore size, by no more than 1/2 thou. This also works and was the only reason we got my bro's Sharps to finally start shooting with accuracy, with black powder loads. Before getting these undersized patched bullet 1 1/2" 5-shot groups at 100 meters, when using more normal groove diameter and larger grease groove bullets & groove diameter paper patched bullets with BP, his groups were 8" or more.