Yes....that is the number one precaution with DMSO....to insure the area to be applied is completely cleaned.
We sometime clean the area (depending on area :) with 3ppm CDS (chlorine dioxide solution), allow to thoroughly dry, then, apply DMSO with CLEAN hands, or, 100% cotton swab or ball.
Typically, 70% dilution from waist, down. 30-40% dilution, above waist. Again...depending on purpose/cause for treatment.
Do NOT apply with or on fingertips with nail polish on ... this will be carried internally, and, you don’t want that.
“Typically, 70% dilution from waist, down. 30-40% dilution, above waist. Again...depending on purpose/cause for treatment.”
Does “above waist” include finger joints?