I have posted on this forum several times about my use of household ammonia for stock cleaning. It works great for stocks that are not heavily oil soaked, but even on those, it removes much of the oil and crud. Then when you proceed to acetone or lacquer thinner, you do not contaminate the much more expensive solvents as quickly. I didn't worry about this so much when I was able to buy DuPont lacquer thinner for under a couple bucks per gallon.
As noted above, ammonia will turn the old dirty grease and oil into a soap by a chemical process called saponification. Soap, of course, is water soluble. I have never done long multi-day soaks in ammonia, so I don't know about any serious side effects that might have. All day soaks or repeated scrubbing and rinsing has had no effect. I do rinse very well and allow the wood to dry completely before proceeding to any staining or finishing. I usually use the household ammonia straight, scrubbing with old toothbrushes. Rinse well with hot water and allow to air dry for several days. Works well. With heavily oiled stocks, oil will continue to leach out into the cleaned surface wood, and acetone or other solvents may be required to finish the job. But this continued leaching can also occur when you use volitile solvents only.
