Various people have asked about OSPHO.
I have not personally purchased from this company. However, this seems like a pretty good price for this item:
Reading the MSDS (Material Safety Data Sheet) this contains only Phosphioric Acid. I would have expected some additives.
I am in the drawn out process of doing some bodywork on my 69 LeBaron and any time that I grind or sand to bare metal I put some of a product like this on the metal to stop rusting. I usually put it on with a paper towel and bare hands, washing my hands very soon there after. It keeps the freshly exposed metal looking freshly exposed.
Fred Joslin