In dealing with non-stabilized blanks, you are dealing with two separate forces of nature that can cause <b>tiny</b> increases and decreases in size. Both have to do with heat and its effect on the structure of the wood.
With oily woods, the heat build up from turning and sanding causes the oil to expand slightly. As it cools, it returns closely to it's natural size. In non-oily woods, the heat associated with turning and sanding dries the wood out. Upon cooling, the wood then attains its natural moisture content based on the surrounding environment, thus causing it to expand slightly.
There are other factors involved, but this is the primary cause for the movement and leads to much of the cracking of snakewood, ebony and the like. To minimize this movement, the blanks need to be turned and finished very slowly over a period of hours if not days. For the most part, the movement is not visible although it may be felt with the fingernail test.
Most very oily woods cannot be stabilized and thus the attempt to minimize movement by boiling and drying these woods. I've had and heard mized results with this method.
Most non-oily woods can be stabilized. The stabilization replaces the water in wood with plastic. Plastic is virtually impervious to moisture gain and loss, however, plastic is subject to softening when heated, either through turning or sanding.
I am currently conducting tests on both snakewood and ebony to see if there is a process to keep the movement down during pen production. The results should be applicable to all woods on a lesser scale. I'd love to have others run the same or similar tests to see if the results are consistent and to see if any conclusions can be reached. If you are interested and commited to a trial like this, drop me an email.
On a side note, a disadvantage to turning stabilized blanks is you sure don't get the lovely scent of wood when you turn.