I recognize the light burl...

How you are doing it it basically the same exact method I use. I stopped using the vacuum method only because I wasnt in a rush for the burl. Leaving it sit for a week is just as successful and I already had a lot of burls to use.

I used mason jars with the vauum because of the strenght of the glass - now I use a giant pickle jar. I have not found a better hardener than Minwax...but I havent looked very far past the shelves of Home Depot, Lowes, and the local hobby store. If you find something please share that info.