I couldn't find it at my local Home Despot or Lowes. Perhaps this is a regional issue. I've heard that costal areas carry the stuff - widely used on boats I understand.
Seems hard to find recently for some reason, it is called 'metal prep' or 'rust converter' sometimes - check your local shops and look at the labels to find phosphoric acid. Not that the ingredients list will show anything more than 'acid' or the like!
I finally found a product at my local Tractor Supply store - cheap too! NAPA has a product that is phosphoric acid with an encapsulator that I use as well - it's meant to ne brushed on.
If you haven't used this stuff before, be careful. Using a respirator is a really good idea. Very Good eye protection is essential too.
Today I was using a spray bottle with phosphoric acid. I couldn't find my good eye protectors so I used standard shop safety glasses. While applying, a shot of the stuff hit me in the eye!
I got to the faucet FAST to flush my eye out, and then rinsed my eye with baking soda in water. I think all is OK but my eye does not feel good tonight.
It's prudent to have a suppoly of clean water close at hand, and also a container with water mixed with baking soda for a quick neutralize.
