Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Alcohol Evaporating
Status: other
Grade: other
Location: WA
Country: USA
Date: October 2007

Does 70% rubbing alchol completly evaporate ? or does it leave any residue why would it need to be rinsed off???


70% of it is isopropyl alcohol. The other 30% is water. Alcohol and water can both evaporate completely, leaving no residue, if there are no solids dissolved in them. Having little or no such solids is certainly one of the main requirements for bottling drugstore grade "rubbing alcohol".

So, no, I see no distinct reason to rinse after briefly wiping one's skin with rubbing alcohol.

But individuals may have fuzzy self-determined reasons. For example, alcohol de-greases your skin somewhat, though not as badly as acetone does. Some people might feel their skin feels more natural, less dried, if they rinse & dry after swabbing with rubbing alcohol. It adds water and possibly redistributes remaining skin oils, and maybe has less of the whitish look of dried dead skin fragments. Try dabbing a spot on your fore-arm with acetone and see if the skin looks dried, whiter. That appearance and feel might be a clue why some people would prefer to rinse after alcohol.

Y'know, I still don't know what purpose and manner of exposure to alcohol you are referring to, whether for sterilization or fever-cooling or accidental spills or many other possibilities...

Jim Swenson

The alcohol in "rubbing alcohol", chemically isopropanol, will leave a small residue at 25 C. However, for all practical purposes the increase at body temperature, about 37 C. will ensure that the alcohol will evaporate. There is no need to "rinse it off". In fact, doing so could introduce pathogens that would be a greater risk than any residual isopropanol.

Vince Calder

Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory