[Sixpackfrank]

I'd like to know what liquid can be mixed with orthophosphoric acid?
I'm going to set up a large tank to dip car panels into a phosphoric acid mix to remove minor surface rust in areas. The panels are stripped down to natural steel. At the moment we mix it with water and even though we've got good results I'd like to eliminate water as the mixing agent. I've tried to mix it with methylated spirit but it separates...what mixes that doesn't seperate and is cost effective.
Thanks in advance.frank.

[Arkcon]

Acids such as phosphoric only work as acids in solution in water, especially as metal pickling, like you're doing.  Also, the ionic acid may just not be soluble in alcohol.  I dont know where you're going to find a fluid cheaper than water, at least on this planet.  Now, if you w as nt to make the solution of phosphoric acid, in water, to be 10% alcohol -- to lover surface tension, remove air bubble formation, kill germs, then that might work.

[Sixpackfrank]

Thanks for the information...the main reason for eliminating water is to ensure that there is no flash rusting in areas between the sheetmetal skins like hoods where I can't see or treat...I know water is the cheapest but if there is something to replace it with that's cost effective I'd look into it. New sheetmetal isn't a problem for flash rusting but 40 year old metal which has been spot sandblasted to get it to clean metal has broken the surface and becomes prone to flash rusting...any ideas???...we do flood the panels with fisholene afterwards so maybe we keep doing what we do...

[Enthalpy]

In several baths maybe? First, let phosphoric acid in water do its job, drip, then rinse with clear water, drip, finish with ethanol containing little water so it evaporates with no residue - like window cleaning liquids do.

Blowing hot dry air would help too. It removes water, but leaves the dissolved salts, or which many (especially chlorides) promote corrosion - hence the clear water.

Phosphoric acid does more than remove rust. It converts steel's surface into a layer that is not bare metal and resists corrosion better.