Shop Tip #185
© Frank Ford 2006; Photo by FF

Learn to know  your plastic containers.  Some, like the styrene portion cup on the right, are soluble in acetone, MEK and lacquer thinners.  A minute after I poured in some acetone, the bottom dissolved and glued itself to my bench. Others like the yogurt container are made of polyethylene, and resistant to all the solvents we have in our shops. A quick rule of thumb is that if the cup cracks immediately if you squeeze it hard, then it's styrene (most drink cups, including styrofoam) and vulnerable to ketones, but safe to use with alcohol, kerosene, naphtha and mineral spirits. If it's really flexible, and hard to break (most packaged food containers, for example) then it's likely to be OK with any solvent.