First, a short talk about curly wood so the explanation about lye water will make sense.
The thing that causes the wood to look striped is the way the grain grew.
Most common wood grain grows straight unless it is close to a limb.
Curly wood grain grows in waves moving back and forth.
Take a look at this drawing to get the idea.
If you have a small piece of curly wood try splitting it along the grain. The result will not be a smooth flat surface. It will have dozens of little waves on it. :shocked2:
As most people who work with staining wood know, the end grain of the wood absorbs more stain and as a result, after staining, it is darker looking than the straight grain that is parallel with the surface.
When a piece of curly wood is shaped or sanded, the little waves get cut off exposing end grain on the surface. The end grain is usually, but not always, in a straight line across the board.
OK. Now for the lye water treatment and what it does.
Lye water dissolves the tannin in the wood and brings it to the surface. Tannin is what gives wood its brown color and even a blond wood like maple has it.
The end grain exposed on the surface in curly wood absorbs more lye water causing the lye to penetrate deeper. It also gives up its tannin more readily than the parallel grain does.
This allows the lye water to bring more of the tannin to the surface making the "stripes" appear darker than the wood right next to it.
Although the lye water treatment darkens the entire stock the difference is not great. The contrast between the end grain stripes and the parallel grain right next to it is however greatly increased.
How to use lye water:
Mix about a teaspoon of lye crystals into a cup of water until it dissolves.
Use a NYLON or synthetic paint brush to paint the lye water onto the wood in a very wet coating.
Allow the lye water to dry.
Using a soft rag, wet it with vinegar and wipe one wet coat on the surface of the wood to neutralize the lye.
The idea here is to nuteralize the lye, not to remove the tannen that was floated to the surface so, do not rub the wood while your doing this.
That would only wipe off the tannin you just worked so hard to bring to the surface.
Let it dry and your done. Applying lye several times will not do anything so don't bother.
DO NOT use a paint brush with natural hair bristles. The lye will instantly eat them and cause the brush to fall apart right before your eyes.
Also be aware, lye water will eat your skin, your cloths and IT WILL BLIND YOU if you get even a small speck of it in your eyes.
Although I always use rubber gloves and a long shirt when I do this treatment, I always end up getting a small speck of the solution on some part of my skin.
Within seconds, a burning sensation will start and if left untreated it will only get worse.
The answer to this is ALWAYS have a glass or cup of vinegar within arms reach.
Splash the vinegar onto the burning area as quickly as possible.
That will neutralize the lye and literately save your hide.
Acid treatments like Aqua Fortis or normal alcohol based stains are applied after the lye water treatment has been done.
As for the color you get with Aqua Fortis, it all depends on the piece of wood you are working on and the kind and strength of the Aqua Fortis.
After heating it, whatever the color results is the luck of the draw.
That's why I usually don't bother with Aqua Fortis and just use good brands of alcohol based stains on my stocks.
Oh. I need to add, if you are working with a cherry stock, the lye water will darken it A LOT.
If you are working with a walnut stock, lye water will turn the surface black, wiping out any nice stripes or curl that it may have.
I don't recommend using lye water on walnut unless your looking for something that looks like ebony.