The burls above ground are often tumors or insect damage. They may be usable,but are mostly hollow and no good. The burls you want for knives are usually root burls from the part of the tree at and just below the ground line. These can be huge (up to several thousand pounds) and have solid wood with swirling grain.They are cut away from the trunk and roots and allowed to dry slowly for years.Some are steamed to make the wood change in character and color.After drying,they are slabbed with BIG bandsaws. The thick slabs are allowed to dry for another period of time.When all is ready they are cut into smaller pieces for things like knife handles. Stabilization by impregnation with acrylic resins is very beneficial to burl woods. The color and pattern may be significantly increased by stabilization. Soaking in Minwax wood hardener, Nelsonite, Paraffin solutions,PEG, and such things is not the same kind of STABILIZATION that you want in a knife handle.It may "stabilize" the wood from rotting or warping,but it won't make it polish or look any better. To get it stabilized right takes large vacuum chambers, pressure tanks, and very expensive chemicals.I send everything to Mike at WSSI.
Stacy