How bad is 1% solution of HF? I was helping my mom clean the driveway rust stains, using some "weak" chemicals, when our neighbor walked over and offered to help. He brought over this nice rust remover poured on the driveway rust stains and it worked very well. So I looked at the list of active ingredients and my jaw dropped. Active ingredients are oxalic acid and hydrogen fluoride. Looking at actual msds sheet it says less that 1% concentration, but still surprised to see HF in $10/gal solution available at Wal-Mart. No spills happened, no exposure or any other oopsies, but I am just curious how bad can it be... I bought 3 gallons of that same cleaner to finish driveway cleaning next week. Usually I'd not use things this bad unless I need to, so might still go with HCl instead of this cleaner. Just curious how careful should I be with 1% solution. Goof off rust stain remover is the actual product if anyone wants to look up msds. It basically states HF <1% and oxalic acid <10%.