Tips on Drying/Finishing Aussie Burls
Aussie Burls, like all other burls, no matter how dry they appear, will still move and "wrinkle" over a period of time if you turn/carve from start to finish. If you don't mind movement or wrinkling, then you can either wait a few weeks to finish, or re-sand and re-finish after it's finished moving/wrinkling. In some cases movement may not be a big deal or may even be desirable. But I suspect most people would rather not have that happen.
So what can you do?
I turn twice, first rough turning and leaving the piece relatively thick, usually sealing with Anchor Seal or Bullseye Shellac, and drying in a homemade dehydrator (see below) for 1 month or more per inch of thickness, then re-turning inside and out (for hollow forms of course) to final thickness. How thick I leave the piece when rough turning naturally varies with the size of the piece. I might leave a 6" hollow vessel about 1/2" thick . . . I might leave a large winged bowl an inch or more thick. In any event, the dehydrator works well . . . If I'm not in any particular rush, I'll leave a piece in the dehydrator longer than the 1 month guideline. No matter how dry the burl appears, I strongly recommend rough turning, then treating in a low-temperature kiln (or oven if you don't have a kiln) to relieve internal stresses, before final turning/finishing.
Alternatively, you might consider cooking in an oven. After nearly 18 months I've yet to see any perceptible movement or surface wrinkling in a piece I cooked in the oven. Never having been accused of being patient, I really don't like to wait a month(s) to re-turn something I'm excited about (if you're not excited, why bother turning the piece?) . . . so I tried cooking a rough turned (3/4 - 1 inch thick) White Top Burl Vessel and Gummy Corrugata and Red Morrel Winged Bowls at 170F (the lowest setting on my oven) for 18-24 hours (there's no rule saying you can't do so longer, I cooked a large Giant Mallee Burl piece for 36 hours) . . . I then turn to completion and finish with either oil (100% tung is my latest favorite), lacquer, a combination of the two, or wipe on poly. I've seen no "wrinkling" and no warping/distortion well after the time I've seen them occur on burls I've turned from start to finish. I believe this method probably works well because the relatively low heat relieves the internal stresses in the burl (like with heat treated steel), therefore precluding it from warping and wrinkling.
Lastly, most everyone has also heard at some point about using a microwave. I personally don't do so, but it works . . . just be careful not to microwave for too long a period at one time or you might actually burn the wood/burl . . . best to do so for shorter periods multiple times.
As for finishing, that is really a personal decision. I am an advocate of 100% Tung Oil, Wipe On Poly, Bush Oil, Waterlox, Danish Oil and Mohawk Lacquer . . . I am also starting to soak pieces in tung oil cut with turpentine (including the inside of rough turned hollow vessels) prior to final turning . . . it really helps these hard Aussie burls cut very nicely and minimize sanding. I don't use Waterlox much anymore, but should you chose to do so there are a couple of tips that will make your use of the product successful. I start by blowing the piece off with air, wiping with Turpentine (and air drying), and applying a coat of the sealer (with a brush or lint-free rag). Most importantly, when applying Waterlox, DO NOT "play with it" if at all possible - meaning, if using a brush/rag, do not repeatedly brush/wipe over the same area, lest you will get brush marks. I allow the first sealer coat to dry overnight (longer depending on humidity), and then apply a second coat of sealer (again, allowing to dry at least overnight . . . when it no longer feels tacky, I will sand with 1200 grit (you might also try 0000 bronze wool), blow down the piece again with compressed air, and then apply a coat of Waterlox Satin to knock down the gloss just a bit . . . gives me a nice deep lower luster . . . (remember, like I said, finishing is a personal decision . . . sometimes I will just use the sealer - like with the large Jarrah Burl bowl in my gallery . . . I sometimes will use BriWax (apply with 0000 bronze or steel wool), Myland's or Satin Wax over the final coat of Waterlox depending on the desired effect.
I like clear Danish Oil because it does not give as much of a yellowish tint (sometimes I really don't want the sapwood to appear yellowish, e.g., the Vasticola Burl carving below) and will produce (with enough coats and elbow grease) a beautiful low lustre finish with depth . . . after waiting at least 72 hours, I will frequently apply Mohawk Sanding Sealer (2 coats then sand) followed by X coats of Gloss or Satin Lacquer . . . you will get far less orange peel than with Deft and have to do a lot less rubbing out. As for the rubbing out, I use 0000 steel wool or 800/1200 grit sandpaper after 72 hours and sometimes (rarely these days) buff using the Beale System (be cautious not to generate too much heat) and wax.