Robert Macy wrote:

Whink, mild HF acid

HF? OMG! NEVER!

Even the tiniest amount of the most diluted Hydrofluoric acid is a
calcium blocker and will stop your heart. The treatment for HF
poisoning is hit-and-miss.

I think you meant HCl or hydrochloric acid, sometimes called
Muriatic acid. Be prepared for fumes and set up some good
ventilation.

Read the label. HF acid.

I tried to etch glass with it, but too dilute.

Instantly removes rust stains almost anywhere. Keep it off aluminum.

Less than $3 a bottle, from memory.

Sigh. Where's the Consumer Product Safety Commission when you need it?