YOU CAN BUY SOLVENTS like acetone and turpentine from a hardware store, but you really shouldn’t. Solvents sold in the hardware store are not refined to the level required for cleanroom cleaning. When applied to surfaces, the hardware store variety of solvents will leave visible residues behind after they have evaporated.
Cleaning With Acetone Or Turpentine
Acetone and turpentine are excellent solvents to be used in the removal of adhesives and other soils. There may be occasions in which solvents like these can be used with knitted polyester cleanroom wipers or hydro-entangled polyester-cellulose cleanroom wipers (both of which are fully compatible with acetone and turpentine solutions). If possible, however, this cleaning should be done outside the cleanroom. Moreover, as a final step, the surfaces should be wiped using a dilute solution of isopropyl alcohol (IPA) to remove any non-volatile residue (NVR) left behind by the acetone or turpentine.
Again, even these solvents should be purchased from a laboratory supply house to ensure maximum purity and minimum residue. Hardware store varieties will leave residue behind.
Keeping Acetone And Turpentine Outside The Cleanroom
It’s worth reiterating: acetone and turpentine should not be used on cleanroom surfaces. These surfaces require routine wiping (usually once per shift or, at a minimum, once daily) to remove particles, NVR, ion contaminants, and the like. The usual cleaning solution used to dampen the wiper is a dilute solution of IPA in deionized water. After wiping there should be no detectable residue left on the surface.
While acetone is fully miscible with deionized water in all proportions, it should not be considered a replacement for IPA as a cleanroom cleaning solution. Acetone is highly flammable and has a vapor pressure at room temperature six times greater than that of IPA. This means much of the acetone will quickly evaporate, often before the requisite cleaning can be performed. In addition, operators will be exposed to higher levels of pungent vapors with acetone. Acetone will also leave behind higher levels of NVR than IPA.
Turpentine, well known for its ability to thin oil-based paints, is poorly suited as a cleanroom cleaning solvent. It is not soluble in water, has no ability to remove polar residues (i.e., salts), has an objectionable odor, and will leave behind high levels of NVR.
Stick with IPA solutions for routine cleaning of cleanroom surfaces. Use acetone and/or turpentine sparingly for removal of heavy soils.
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