What is the best way to get rust out of an original gas tank? I have heard that vinegar works. If that is true could a person use straight acetic acid? Does diesel work? Thanks!!!
I use phosphoric acid. Phosphoric acid converts rust oxide to zinc oxide (similar to galvanizing. Phosphoric acid is not a "bad" acid it is about the same acid level as orange juice. They also use it to clean the inside of milking equipment and lines at dairy farms.
Donnie, what was your source for the phosphoric acid.....Thanks....J.
Phosphoric acid will not turn Iron oxide(rust) to Zinc oxide. It reacts with the iron oxide and converts it to Iron phosphate .It will also form a layer on the surface of the metal(tank) which resists further oxidation. It is the reason it is used as a metal prep. Good stuff,and I too would like to know where to buy some. Used to see it in some toilet bowl cleaners,but if you read the labels ,they are about all Hydrochloric now. Big Brother at work again...
Google phosphoric acid. Big brother Amazon lists it in various forms.
Eastwood sells Zinc Phosphate in gallon jugs.
Thanks Donnie. I work in agricultural sales so I am familiar with phosphoric acid. My manufacturing company uses it in its process of making products for ag. The iron phosphate makes sense since phosphorus is negative charge, iron is positive (cation). That should make a hard bond. I have some decent tanks so I really want to use original if at all possible. Thanks to you all!
I use "Klean Strip Phosphoric Acid Prep and Etch" that I get from the local Home Depot.
Phosphoric acid metal conditioner: DuPont 57817S. You can order it at O'Reilly. We used it in the sign factory to prevent rust from forming under paint.
Ron is right. It's been a couple of years ago but the last time I bought some it was from Home Depot.
Thanks Ron, I will look for that.
Buy the metal conditioner at an automotive paint store. Most of them will carry the Dupont product Steve mentioned or equivalent.
I buy it at my local ACE Hdwr. under the name Ospho, made by the Skybryte Co. 3125 Perkins Ave., Cleveland Ohio.
My bad, Iron phosphate is correct, I do not know where in my brain zinc phosphate came from . I used to buy my pure phosphoric acid from a local dairy. I have not bought any in several years. best I remember it was about 165.00 for a 15 gallon drum, but it mixed 20-1 ratio with water. I had a plastic 55 gallon drum dip tank that I put most of my parts in to de-rust them. I like diping because it soaks into the seams and converts and kills the rust. I have only read about "do not dip hardened parts", but they say do not dip any hardened or tensil strength type of items. things like spindles, axles, bearings, crankshafts, camshafts, rods, valves, gears, ect. It is supposed to change the surface molecular structure of the parts in a undesireable way.
If you are using the epoxy primer, DPLF 90 (or any of the other numbers, 90 is the black version) do not phosphate first, the DP sticks better to bare metal and provided greater corrosion resistance than if you phosphate the metal. This is noted in the printed documentation & I found it true when I did a corrosion resistance test of various coating systems decades ago (at the time, I thought it was an anomalously in my test, but the next year the MSDS stated this).