Do you mean REAL freeze-drying?
Has anyone had any success with freeze drying rough outs?
Presently I am trying to get to a large amount of maple that has spalted and I worry it might go too far if I leave it any longer. I have a freezer partly full of chunks of maple but wonder what will happen if instead of boiling or/and sealing I just put the rough outs (bowls and hollow forms) in the freezer.
I also considered coating either the end grain or the complete rough out with Anchorseal before placing in the freezer.
Anyone tried this?
Back in the mid-2000's I tried quick-drying some small "green"-turned bowls in the lyophilizer in my lab - this would be considered 'true' freeze drying, as in deep-freezing the mini-bowls in liquid nitrogen and then transferring the frozen wood to a vacuum chamber and maintaining it at less that 50-100 torr to sublimate the frozen water and remove it from the wood. The results were less than stellar. For wall thickness of about 3/8" or less, the wood seemed to apparently dry completely, but for wall thicknesses 3/8" to 3/4", there seemed to still be water present in the deepest parts of the side grain portions of the bowl; the end grain seemed to be fairly dry. This summer I will try some vacuum drying in a chamber I recently acquired, but this is more to experiment with potential reduction in shape distortion, as well as use of steamed & saturated wood to make some unusual shapes in thin-walled bowls. Given that using a lyophilizer might be considered the optimal freeze drying conditions under vacuum, I concluded it was not worth pursuing on a larger or "serious" scale. Some variation in freeze drying effectiveness also likely depends on what species of wood is used - i.e. open grain (ring-porous) versus closed grain (diffuse porous), presence of tyloses or not, relative areas of end-grain versus side grain in the shape of the piece, etc. beyond just wall thickness.
Given your suggestion of simply putting your rough-outs in the freezer, I speculate that you would be extending the drying time by leaps and bounds compared to ambient temperature drying. Sealing the entire blank in Anchorseal and then storing it in a freezer might result in 'suspended animation" where virtually no drying would occur at all. If you want to preserve the wet bowl for future turning, this would be OK, I guess, but there would still need to be a dry-down time after the subsequent turning, regardless. (You wouldn't likely be gaining much, if anything, with the freezer treatment) Freezing, itself, (i.e. -20^C) will not likely kill all of the fungi, and once the wood is warmed up and if still moist enough, the fungi will continue their gradual decay of the wood.
If you are worried about the spalting fungi continuing to degrade the rough-outs after they have been turned, one of the easiest ways to stop the fungal activity I have found is to soak the rough-out in denatured alcohol (methylated spirits for you Brits...) - not necessarily to speed up the drying, but more to kill any living fungi
in situ so they do not continue to grow in your roughed bowls. This has worked for me for years - and I turn a fair amount of spalted wood. The piece below was turned from fresh cut river birch that spalted in the log sitting on my driveway for about 7 months. I rough turned the hollow form in one night, soaked it overnight in denatured alcohol, and then allowed it to dry for several months. No evidence of continued fungal growth was seen in the rough-out, even though the end-cut from the same log section had lots of fungal growth evident after just 2 days (this usually is observed as fuzzy white hyphae on the wood surface). I suggest you try this method and free-up the freezer for storage of something nutritious!
Good Luck!
Rob
