In solitary, he had hosted an elderly man with a limp who had applied acid to change - painfully - his fingerprints.

Some people apply folic acid directly to the gum for treating gum infections.

Do not apply salicylic acid and sodium thiosulfate topical to large areas of open, broken, burned, or infected skin without first talking to your doctor.

He applies muriatic acid to metal to develop shades of turquoise, blue, green or rust.

As a prevention measure, cover the surrounding skin with a doughnut-shaped pad or bandage when applying salicylic acid.

Do not cover the affected area after applying azelaic acid.

Spit-biting is a process whereby the printmaker will apply acid to a plate with a brush in certain areas of the plate.

Before applying salicylic acid, soak the wart in water to help loosen and soften skin.

They applied acid to free the fossil from the surrounding mineral.

Only a qualified doctor or other healthcare professional should apply aminolevulinic acid.