After building circuit boards from artwork or kits, it’s a good idea to clean all the rosin from the board. This makes it easier to see bad connections and shorts, and also gives a cleaner appearance. You may have been using acetone (acetyl ketone or propanone); while it does work very well, it has some definite drawbacks. It is highly flammable, its vapors are smelly (not to mention toxic), and it attacks many plastics (especially styrene and blends like ABS which contain it).
A much safer substance is methanol, also called “methyl alcohol,” “wood alcohol,” or “methyl hydrate.” It is not nearly as flammable, much less toxic, virtually odorless, and works almost as well in removing rosin. Furthermore, it is harmless to plastics, so you can use it as a “bath” for your newly-completed boards without worrying about components literally dissolving away. Simply pour some into a dish containing your board, and cover it with a bowl; a few minutes later, remove the board, dry it, and inspect it for questionable connections.
Methanol is the same stuff that is mixed with gasoline in making “gasohol,” so if you have a purveyor of this substance in your area you can probably get it very cheap (under $1 a gallon). If not, you can get it at auto-supply stores under the name of “fuel-line de-icer,” albeit at a much higher price.
An even better substance (non-flammable and less volatile) is 1,1,1-trichloroethane, also called “methyl ether” or “safety solvent.” It has a stronger scent than methanol, but is not nearly as unpleasant as acetone. It is available from most industrial chemical suppliers at lower cost than acetone. Freon TF is also good, but is expensive and a little too volatile to be usable in a “bath.”
-fn