I have rough turned a 22"x5" bowl from green walnut using the 10% rule for thickness; the walls and bottom are 2.25 " thick. I have coated it with Pentacryl to stabilize it during drying. Jimmyjames thinks it may take a year for the bowl dry for final turning and of course I would like it to dry quicker. Does anybody have any suggestions to speed things up? I was thinking of letting it dry to some point, turning it to 1" thick and letting it dry the rest of the way from there. I have no idea if this would help or if it would cause problems and I don't know what would be the ideal moisture content for this second turning. Any thoughts or recommendations on this idea?
Drying a large rough turned bowl
- Thread starter AustinTom
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After someone (Grumbine) suggested turning the bottom a little thinner I have with no problems. It will lose water quickest through the end grain and the bottom is mostly side grain. So for one with 1” walls I taper down to about3/4” in the bottom.
You may be able to rough turn twice (I have never tried it). It will still be the wettest in the center and if you take it down to one inch at the second turn it may warp too much for the finish turning. That is just a guess.
Here is a link to equilibriums; Austin is on about page 11. Looks similar to Harrisburg and I figure it is good to go at anything below 14-15.
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf
I have never used Pentacryl (I use Anchorseal) but I only coat the outside and maybe an inch down on the interior. I have had no problems but it may not work for you or with that product.
You may be able to rough turn twice (I have never tried it). It will still be the wettest in the center and if you take it down to one inch at the second turn it may warp too much for the finish turning. That is just a guess.
Here is a link to equilibriums; Austin is on about page 11. Looks similar to Harrisburg and I figure it is good to go at anything below 14-15.
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf
I have never used Pentacryl (I use Anchorseal) but I only coat the outside and maybe an inch down on the interior. I have had no problems but it may not work for you or with that product.
You may want to include the photo of it tom, this bowl is somewhat shallower and the sides aren't as tall , I would think it would "football" less since the sides are shorter? Maybe?
I don't turn a lot of bowls, but when I do...( NO, not Dos Equis 
) I follow the lead of the bowl turners. I boil them. Boiling will not prevent warping, but will HELP eliminate cracking, and will help decrease your drying time. If you treasure your rough-out though, you will not push the drying time beyond that. From the boiling pot, I'd put it in a plastic sealable bag and spend the next couple of weeks turning the bag wet-side out on alternating days.
) I follow the lead of the bowl turners. I boil them. Boiling will not prevent warping, but will HELP eliminate cracking, and will help decrease your drying time. If you treasure your rough-out though, you will not push the drying time beyond that. From the boiling pot, I'd put it in a plastic sealable bag and spend the next couple of weeks turning the bag wet-side out on alternating days.
I have found the Walnut dries faster then most of the woods I turn I have roughed out 10 bowls and am working on 8 hollow form roughs today. After the first week or 2, when they are surface dry I stack them in a coolish place to finish drying. Getting the surface dry is important to prevent mold. I boil Madrone, and am trying it with Holly, ( I loose about 25% of my holly due to cracks too deep to turn out). I would not waste the gas boiling maple, walnut of any other hardwood.
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jimmyjames said:
Here is a link to a picture of the bowl in another thread. The walls are 5" high an the radius of the curve of the sides is about 4".
http://woodbarter.com/attachment.php?aid=23356
AustinTom said:
Rounded over corners fair better than squared off corners (rim).