Veneer Flattening

This viewer question comes from Thomas. He writes:

I have never attempted to do thin veneers before, but since I always like to do things over the top, I chose to purchase not just a regular veneer but a yew burl one that has more waves and ripples in it than an elderly fat farm on nudist Wednesday. My plan was to use it as a top for a humidor. That being said, my question is, how do you go about veneering such a complicated surface? Do you have a good method for flattening the burl or does that happen once it’s pressed and glued to the surface? Do you use contact cement? Etc. Got any tips?

And here was my reply: Hey Thomas. I like your taste! In veneer, that is. Not in your choice of nudist colonies. As for the veneer, you should definitely flatten the veneer before gluing. This is an easy enough process that can be done in about a day. First you need to make a veneer flattening solution. Here’s a decent recipe (there are others):
Four parts water, two parts glycerine, one part alcohol, and two parts plastic-resin glue. Mix thoroughly and apply to both sides of the veneer with a brush. Saturate it pretty good. This solution will soften the fibers and allow them to flex. But the glue in the mixture will keep the veneer in whatever position it dries in, so you need to press the veneer flat while it dries. To do this, it’s a lot like setting up a traditional veneer press. Use two plywood cauls to make a sandwich. Cover the veneer on both sides with fiberglass window screen and place some newspaper between the fiberglass and the cauls. So your sandwich would be: caul, newspaper, screen, veneer, screen, newspaper, caul. Make sense? Then you just need to clamp the two cauls together and let it sit overnight. Change the newspaper and let it sit for another 12 hours. If the temperature is cooperating, the veneer should dry within a day or so. If not, keep it pressed and keep changing the paper as needed. Once dry, it will be nice and flat and it will stay flat. But remember, the embedded glue will inhibit the absorption of stain, so only do this technique with pieces you dont plan on staining.

As far as gluing goes, my favorite veneer glue is plastic resin glue. I like Unibond 800. You could use contact cement, but there is just something about working with that stuff that I really don’t like. I really like a good wood to wood contact when it comes to veneering and using contact cement feels more like adhering the veneer to rubber, then to wood. In the long run, you will be better off with plastic resin glue.

I know there are numerous other flattening solutions out there. I am curious if anyone has one that wont be an issue with staining later. Respond to this post if you do.