Get more Tips, Specs and Technical Data!

Did you know... this Forum is a service of the Studebaker Drivers Club? For more technical tips, specifications, history and tech data, visit the Tech Tips page at the SDC Homepage:
See more
See less

Phosphoric Acid

  • Filter
  • Time
  • Show
Clear All
new posts

  • Phosphoric Acid

    has anyone ever used phosphoric acid for rust removal? if so what was the steps you took. thanks
    Kevin Phillips

    53 commander

  • #2
    I have used lots of it in our small powdercoating job shop. Stopped using it when a product called PIcklex came out, This might get you there. This product is far better than they claim. hope this helps. Its great for converting and stopping rust for a long time frame , so you dont have to rush things worrying about surface oxidation creeping back in a few minutes. Tom O.


    • #3

      It would be nice if the site had the cost of the product somewhere....
      64 GT Hawk (K7)
      1970 Avanti (R3)


      • #4
        64 Champ long bed V8
        55/53 Studebaker President S/R
        53 Hudson Super Wasp Coupe


        • #5
          I use phosphoric acid to neutralize rust remaining after I sand/grind most of it away. The acid is fairly cheap and can be bought at most any paint store or by the gallon at home depot. Don't ask for it as phosphoric acid, though. That will result it all kinds of comments that we don't carry it to some excuse about it being outlawed, all of which are signs of incompetence on the part of the sales clerk. I first encountered it under the name ospho. Look at the label of whatever you find to find the phosphoric acid as the major content.

          I use it mostly on wheels that I am cleaning up and on body panels that I am making amateur repairs upon. Professional body men have better products to use. I also use it on chrome bumpers, etc just before applying at least 2 coats of polish. It keeps small rust spots from spreading, in my opinion.

          I do not use it to try to "dissolve" rust. I use it to chemically neutralize the rust remaining after physically removing most of it. It just doesn't make sense that the acid can work its way through thick rust. It is a relatively weak acid in the chemical hierarchy, which is why it is safe enough for us to use in our hobby.

          Using rubber gloves (or not if you avoid direct contact with it except for short periods) I rub it on using a throw-away rag or towel. Leave it on for the time specified in the directions, then wipe it off using a lightly damp clean rag. As soon as the surface is dry apply primer or sealer or polish to prevent new surface rusting.


          • #6
            The use of phosphoric acid is really difficult in shops as we have., lots of environmental issues regarding disposal of suchlike chemicals. A few years ago a chrome plating shop was fined and not lightly. It cost the owners their shirts. Picklex is one of the only products that has approval in Canada. You never have to worry about spills. Just hit it with water. Aircraft rebuilders like it as it doesnt eat aluminum but only the oxidation, And like in previous comments its a great treatment prior to welding, particularly Tig welding. We paid $80/ U.S. gallon 5 years ago then diluted it, It last us aroud 4 months. It really came in handy for treating old Harley Davidson frames and springer forks, all the fine rust inside tubes gets out without hassles of oven explosions from out gasing pre-heat crud getting all over the place. I drill tiny holes in hidden areas then load up tubing with picklex, leave awhile then rinse all the oxidation out then blow out, when you look inside tubes it looks brand new. After I powdercoat frames and tubing, I grease/oil the tubing so this ensures longivity. Tom O.


            • #7
              quote:Originally posted by Harvey

              I have used lots of Phosphoric acid, it is a "relatively" safe acid to use for pickling,rust removal and ferrous metal passification. Please remember it is an acid and must be respected use gloves and goggles when working with it. Also, have good ventilation, no closed containers or lids. Acids and metal generate dangerous hydrogen gas, just like your lead acid batteries.
              A good source for a blended phosphoric acid is and your local air conditioning wholesale supply house. Ask for ice machine cleaner.The base is phosphoric acid along with citric acid..
              Used acid can be neutralized with baking soda before disposal. Add it slowly until the bubbling stops. Just be careful when using any
              acid, including vinegar which is diluted Acetic acid.


              • #8
                If I'm not mistaken phosphoric acid was supplied under the name
                "Metal Prep" and was made by duPont a number of years ago.
                I also used it after grinding most of the rust off a steel part. The Metal Prep helped my clean up the rest of the rust before priming.

                '59 Lark VI Regal Hardtop
                '59 Lark VI Regal Hardtop
                Recording Secretary, Long Island Studebaker Club