Hi
 Well, There are  2 different types of preserving. First, is just general preservation to make the wood a little more resistant to rot and or to give it a bleached, deadwood look and then there is wood hardeners that basically are used on already soft or spongy (punky) wood to save it (can be used as a preventative as above also).
 What is commonly used for preservation is lime sulphur solutions (jinn fluid). This is also known dormant tree sprays because they are often used in a very dilute solution on deciduous trees in winter to kill pests and fungus, etc. They can be used full strength or diluted a little depending on the artist. It is best used in dry weather. If used straight, they go on looking yellow, but a few days drying in the sun, they turn the wood a more white color. Repeated applications turn the wood more white and also protect it better. Unless you have a juniper, it would look a little unnatural for it to be so white. most people will add various amounts of india ink (I use black water color) to darken it up. You can use a light dilution at first then add more coloring with the next applications until you get the color you like. Stark white would absolutely look unnatural on a maple. The texture and finish of the wood would remain the same. Lime sulphur wont make it shiny.
 You can carefully use a small torch on the inside of the hollow to burn it (this also helps preserve the wood, but please be very careful to cover and protect all living surfaces including your fingers), then use a wire brush and by hand or dremmel machine, brush out most of the black burned surface and apply the gin solution over that. You can do it so the deeper part of the hollow has more of the burn left causing an interesting and natural looking hollow. There are many books and web sites that show this technique.
 The wood hardeners like minwax in the USA, actually permeate the rotten wood fibers and effectively turn it into plastic. Get rid of the very spongy wood first and apply as many coats at 1 time as the wood will absorb. Try not to spill it on the live parts, but I have never had anything die from getting dripped on by accident. You can use the gin solution first to get it the color you want then the wood hardener, as once you use the wood hardener, the gin solution will not penetrate it.
 There is a new product some people are using called paralax 44d. It is used by museums to preserve paper and wood artifacts without changing the look of the material. It comes in little plastic looking beeads that you mix with various different solvents you can get at a paint store or even ispropyl alcohol (rubbing alcohol). do a google search for it including the word bonsai and you should find some articles on how to use it. After the wood hardener is dry, it will look slightly shiny, but you can brush it slightly or in the case of the paralax, you can rub some alcohol or paint thinner lightly on the surface to take away the shininess. Try see these methods for yourself or at least really study them on line or from books before you apply these potentially toxic chemicals to your valued specimens. I used practice on dead tree stumps first that I found at the beach or by the side of a river to improve my carving, preservation techniques.

Yes, paraloid is what I was referring to in the post before your Chris, I just got the name wrong. I got my from a book preservation company called talas in New York (talasonline.com) I recreated the experiments on bonsaibasho using an old rotted Xmas tree trunk.
 I used paint thinner, rubbing alcohol, denatured alcohol, and acetone. I couldn't find toluene, etc for sale here in California, so its probably banned. The acetone worked pretty good in dissolving the beads( the other stuff failed badly). I like that you can control the viscosity of the paraloid by adding more acetone or paraloid. I use the thicker viscosity as a glue for broken jins etc.
 I found that its easier to dissolve if its warmed to slightly above room temperature. I dissolve it in an aluminum soda can that I cut the top off of, put some paraloid with about double the amount of acetone in it and put that in a bowl with pre warmed up water. Don't heat the stuff directly as the acetone is flamable and an explosion would wreck your day of bonsai fun. if you use water above 100f, you will get some cavitation (Tiny bubbles) in the final solution that shows up on your wood and ruins the effect.
 Like you said, it absorbs great and any shine you may get disappears with a tooth brush dipped in rubbing alcohol. I painted the live trunk and some leaves on a ginkgo sapling and not only did it not kill the tree, but the leaf stayed green and alive till fall! You can add some sumi ink or whatever water color to the solution if you want, but it will be hard to change the color after the stuff is in.
 The only advantage I see minwax has over the paraloid is minwax has a fungicide, but you can use a fungicide on the wood first (Like lyme sulphur) if you want, but since this stuff basically turns your wood into plastic, fungus won't attack it anyways.
Talas sells other paraloids for gluing and preserving ceramics (works great on broken pots) and metals. In fact, there was allot of stuff in their catalog that we can use for bonsai. Their prices were excellent and I got a huge bag of the paraloid for like $45 delivered (easily = to 10 or 15 bottles of minwax).
Thanks!

Thanks Elliot for the extra info on usage!  Great to hear some others have tried and liked it.  I'm going to give it a try as I've never been a big fan of lime sulfur.  Having lived in Cali, I forgot how much stuff they have outlawed.  Now Toulene?  I know they used to sell it.  Same thing here in IL, but not as bad.  I bought a bottle of Malathion in Tx. over Xmas as it's illegal here in IL to spray for fleas and ticks in the back yard next spring.