The rule of thumb for thickness is 10% of the diameter. This gives room
to re-turn after the wood warps during drying. The rule can be fudged
if you're familiar with how much the particular wood is likely to warp.

I wait about 6 months on a 10 inch bowl with 1 inch wall thickness. I
don't pack the paper bag with shavings unless I'm trying to encourage a
bit more spalting during the drying process. Some wait longer, but if
it "feels" dry, it's probably ready. Again, experience will guide you
after some time. I'd suggest you start with 6 months time, then
experiment until you have developed your own "feel"" for the wood by
species in your climate.

I've never heard of using a stick. It may work well on some woods, bu
will likely encourage others to split. The wood moves during drying to
relieve internal stresses that develop. These stresses are what causes
splitting. If you keep the wood from moving, the stresses are not
relieved, and it seems splitting is more likely.

The purpose of bagging is to slow drying, allowing less difference in
moisture content between the outside and inside of the wood. This also
reduces stresses by keeping the shrinkage rate more uniform. Packing
the wood in shavings further slows drying, as more moisture must move
through the paper barrier.

Jim

william kossack wrote:
I'm trying to solve a problem coming from the fact that most of my bowls
are turned from sopping wet wood.
I've not had too much problem with cracking but my finished bowls are
warping considerably. As an experiment I've started few new bowls using
very wet wood and then buried them in paper bags filled with fresh
shavings inorder to slow the drying process. Using this process I have
placed 5 bowls in bags over the past month and only found cracking in
one. However that one had a rather large tenon and a bottom much thicker
than the sides. None of the others appear to have cracking in them.

One question is how long to leave the rough turned bowl in the bag. In
denver the humidity runs fairly low but I don't know if that should be a
factor or not. I've heard anything from a couple weeks to many months.

Another question is how thick to leave the rough turned bowl. This
should depend on how much warp I might get as the bowl is drying. Most
solutions to the problem of cracking and warping seem to mainly be for
cracking.
One solution would be to wait until the logs/blanks are dry before
turning them but frankly I don't have enough room to store large logs
for years and years.

I ran upon a couple unique solutions for the warping problem and I'm
wondering if anyone here has tried them.

Some ausi turners mentioned putting a stick into the roughed out bowl
against the grain ends to prevent warp from closing in from that
direction. Another post suggested circles cut from MDF.

Any thoughts?