Mr. Don,
I am afraid I have no experience with Holly. But here in the Pacific Islands many of the turners use a product called Turners Choice from Cedar Cide. The link to their web page is
http://www.cedarcide.com/woodturners.asp (I don't sel this stuff or have any interest in the company by the way)
It is a non toxic product marketed as a wood stabilizer. It gets used for the same purpose soaking wood in Denatured Alcohol. Remove moisture, stablize the wood, reduce cracking, etc. It also seems to kill and drive off certain insects we suffer from here in Hawaii like the Powder Post Beattle.
I have been using it, but only on a few bowls so far. Nothing challenging yet though.
The turners here who use it swear by it. They started using it for Koa, a local wood, highly prized for bowls and calabash forms, and a wood that sells for big dollars if you have even modest skill as a turner. The turners found that they had to rough a Koa bowl and then sit it on a shelf to dry for 6 months to a year before they could safely do the final turning and finish it. Even then they were losing an unacceptable number of bowls to cracking as they dried.
They tried a variety of things but didn't find anything that satisfied them until they tried the Cedar Cide stuff. To use it, they rough turn from green stock, then paint the stuff on liberally and let it soak in. For Koa they let it dry about 2 weeks. For other woods they let it dry about 3 days. Then they do the final turning and finish it. All done. Once dry it does not appear to alter the color or affect the woods ability to take a finish. It costs about $50/gallon on the mainland, $60/gallon here in Hawaii, but they pay it readily because of the way it has changed their turning timetables. Understandable. If a turner can take a highly priced bowl from green to the gallery in under a month versus having to set it aside for year, and risk losing a fair amount of their work to cracking while they wait, then this is a great stuff.
I also believe a few turners are doing the alcohol soak method as well, and they seem satisfied with that. Someone in Hawaii wrote to me in another post about that and I will be darned if I can remember who. If that person is reading this would you mind chiming in please???
The wood I want to try this on is Ohia. It is very dense, and as it dries has a tendency to crack like mad. I have done OK with it so far but want to try it with some of the Turners Choice on it and see how it changes this characteristic. I get the impression Ohia does not sell well in galleries here, but I really like the looks of it myself. Very Subtle figure and colors. (I have 2 pieces of it posted in my gallery here if you want to look) So it would be nice if I could get it to behave better, even if I only end up using the wood for personal stuff rather than for sale.
I hope this helps a little!! Let us know what you end up using!!! If you want to try it but don't want to spend the bucks on a test let me know. I will be happy to see if I can find a waterproof container I can trust and ship you some. I don't believe this is flammable so it should be OK to send from here.
Dave