Q. First let me say how much I have enjoyed your column. It is very informative and I learn something every month. However, I must take issue with your reply to B. L. in the February 2006 issue. Although there is no doubt that he needs to stop using toluene for hand wipe cleaning due to its toxicity and flammability, there are a number of perfectly acceptable alternatives.
For instance, our patented solvents (Name and supplier withheld) were developed specifically for hand wipe cleaning in their manufacturing plants and are now the most widely used hand wipe cleaners in the industry. These solvents were designed to meet environmental regulations, have flashpoints above 100°F, minimal toxicity and clean as well or better than 1,1,1, MEK, toluene, acetone, etc. I think you will agree that aircraft surfaces have to be as clean as possible prior to painting, coating, bonding or sealing and hand wipe cleaning is the preferred method due to the size, nature and assembly location of the parts. Not surprisingly, these solvents are also used in ultrasonic cleaners and dip tanks where feasible.
I am not trying to toot our own horn but just to point out that there are hand wipe cleaners designed to meet exactly the objections you raised in your reply. Our competitors also have good hand wipe products, just not as good as ours.
The solvents you mentioned are not terribly effective cleaners although they are far safer to use than toluene and they are the most inexpensive option. Aqueous systems have their own problems in treating waste water streams as well as the initial capital outlay and continuing maintenance costs. Each cleaning need will have a cleaning process that performs in the most effective and cost efficient manner and hand wipe cleaning is a very efficient way to clean in many applications. Proper training is important but that’s true for all processes. Thanks for letting me sound off. I appreciate the information resource that you and your fellow columnists represent to the metal finishing industry. J. M.
A.Thanks J. M., for showing your appreciation of my and fellow columnist’s writings. As an officer in the USAF retired reserve, I agree that aircraft surfaces have to be as clean as possible prior to painting. However, what I said to B. L. in the February Painting Clinic was, “ In my opinion, solvent wiping is a poor cleaning method using the best solvent. Since the cleaning solvent becomes contaminated with the oily soils removed, there is too much danger of recontaminating surfaces due to infrequent solvent and wiper changes.”
After reading my answer to your comments, I think you will agree that I am not against solvents nor the solvent wiping method. Instead, I am against the misapplication of the solvent wiping method, as stated above. I know that, in some cases, solvent wiping is the only method that can clean certain products. I am sure your solvent, when properly applied, does the job. Owing to the policy of this column I couldn’t mention your solvent and company name.
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