Oldwood said:
I have not used this product but reviews indicate it works well.
https://www.rockler.com/polyethylene-glycol-peg-green-wood-stabilizer
Lots of other places to buy that is just the first one that came up.
There are some treatments that will pressure treat wood with catalyzed plastic that will virtually stop moisture shrinkage/expansion, but it's a pretty expensive deal, both the equipment and the artifacts. Plus to me, it almost seems like it's not really wood any more. My understanding is that these don't turn the wood into a solid block of plastic, but instead the plastic coats all of the internal surfaces so that moisture may get into the wood pores, but can't absorb into the wood tissue. It may be that the stabilizer that Rockler sells works like that, but without pressure treating it, it would only absorb into a thin surface layer of the wood - I've heard of products like that. If I were going to use it, I'd do more research into how it works. If you have to make a solution and soak your wood in the solution (per the Rockler Description), it can really only be practical for small parts - sounds like things that would fit in a 5-10 gallon container unless you wanted to mix up a horse trough worth of it. Furthermore, it would take a good long soak to get anything other than superficial penetration without pressure, so perhaps the intent is only to protect a thin layer of wood close to the surface. Another factor to consider is how the product affects any finishes or glues that you might be using.
What you are trying to stabilize is also a factor. If you are trying to stabilize something really porous (like "punky" wood that was in the process of rotting, but not quite there yet), it might soak through really quickly, but in that case you probably want something that will add strength, not just moisture resistance. (I've heard of people using CA glue for that, but I've never tried it.) If you are trying to stabilize an oily wood like teak or cocobolo, it may absorb the product differently than cherry or walnut - after all, oily woods already have oil in the wood tissue. Open grain woods like oak may absorb better than closed grain woods like hard maple.
A custom woodworker or hobbyist can treat wood to slow down how fast the moisture content changes in other ways. The best known is coating end grain in something like wax or acrylic so that the moisture exchange happens more slowly through the side grain. Turners sometimes store wet-turned blanks in plastic bags which they open every month or so to slow down the drying process. Some finishes will slow down moisture exchange enough to minimize seasonal expansion/contraction. Thick surface finishes that are (nearly) impervious to moisture and many (20-25) wet-sanded coats of oil that eventually hardens come to mind. Nothing I know of aside from the pressure injected plastics will prevent issues when moving from a dry to wet climate, or vice-versa. However, slowing down the moisture content exchange will mitigate some, but not all, issues.
There is no substitute for designing for expansion and contraction. Knowing the properties of the wood you are using, including both radial and tangential shrinkage, can affect the design. Lining up grain, floating panels, breadboad ends, manufactured panels, etc. are all techniques that contribute to a design that isolates a piece from moisture problems.
When talking about the properties of wood that woodworkers generally care about, I heartily recommend "Understanding Wood" by Bruce Hoad. It's not an easy read, but the info is invaluable.
