Cleaning in the 60s

Question:

You’ve probably seen this question/issue pop up frequently. We are an environmental consulting firm doing some research for an industrial client. We are trying to find a definitive information source(s) that lists the predominant solvent for vapor degreasing in the period 1962-1972. We have significant anecdotal information but nothing that’s firmly based.

Would you know of an article, journal, book, etc. that might be helpful? B. M

Answer:

Unfortunately, I do not know if the hard published facts exist out there. I can tell you that 1,1,1-trichloroethane (TCA) was first introduced in the mid 1950s as a metal cleaning agent. It gradually replaced other solvents due to its lower toxicity that in turn lead to higher allowable exposure limits. Due to their very similar physical properties, trichloroethylene (TCE) was the chlorinated solvent most affected by the introduction of the TCA.

It is possible that the lower toxicity of the TCA is what contributed heavily to its eventual phase-out due to the Montreal Protocol and the Clean Air Act Amendments. Because of the lower exposure limits and relatively low cost, it could be used without much regard for containment of the vapor. This in turn led to very high emission levels of the solvent over the period of years that is alleged to have contributed to the depletion of the stratospheric ozone layer.

To answer your question, it is likely that in 1962 trichloroethylene was the predominant metal cleaning solvent, but by 10 years later, 1,1,1-trichlorethane was the primary solvent of choice. I have forwarded the question to the Halogentated Solvent Industry Alliance (HSIA,www.hsia.org) and will let you know in a future column if I receive any further information from them.