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painting rusty steel

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  • painting rusty steel

    I have 2 one-trip 20 foot seacans that got cooked in last years wildfire. One is
    pretty well rusty brown all over with roof and sidewalls bulged out from stuff going boom while the other is structurally straight and has quite a bit of good paint on the
    outside, with bubbled and worse in some areas. Inside is totally black. While not in the best shape, they are too expensive to replace and are still weather tight [no floor in one] so painting the outside [and inside of one] is appealing, however a proper prep job, sanding off rust etc. is out for me. I'm thinking of pressure washing both then
    painting them with...what? Any suggestions for a paint that will cover tight surface rust
    and/or tight but imperfect paint and last for a while? I plan on using a spray gun.

  • #2
    Perhaps investigate rust conversion paint. Google it for leads on brands and supply. I used some decades ago on a rusty vehicle. It worked fine. Color painted over the 'rust primer'. That vehicle is long gone but the coating did its job for a number of years.
    Bill Pendergrass
    Rotec RM-1 w/Rusnok head
    Atlas TH42 QC10

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    • #3
      I was reading recently that Penetrol is a good additive to add to oil based paint when painting rusty metal.
      From what I read it helps penetrate tiny pores in the metal which helps coverage and adhesion.
      Never used the stuff myself but apparently it is used a lot with good results.

      https://www.google.com/search?q=Pene...firefox-b-1-ab

      https://www.lowes.com/pd/Flood-Penet...-fl-oz/3376246

      Good luck with it.

      Dwight

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      • #4
        Get a sandblaster tip for your pressure washer
        and wet blast them. Also get a soap injector
        for the pressure washer and inject phosphoric
        acid while wet sand blasting. This will convert
        any iron oxide to iron phosphate, which is a
        passive surface coating. Then use an alkyd
        (alcohol-acid) based paint.

        -Doozer
        DZER

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        • #5
          I have used a pump up garden type sprayer to spray phosphoric acid on rusty steel and then used an airless sprayer with oil based paint for a finish coat.
          Location: The Black Forest in Germany

          How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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          • #6
            If you really want the paint to last try using POR 15. If you prep it according to the instructions and use 2 coats it will never come off. I have used it to paint 2 permanently mounted LP tanks on motorhomes. The tanks were extremely rusty with the original paint peeling off in sheets. I followed the instructions and both turned out excellent. One was painted about 12 years ago the other about 3 years ago. The paint forms a hard shell. It's almost impossible to chip even when hitting it with a hammer. I used the silver mainly because it has more metal content and will make a smoother finish over rough areas. For the finish coat I used Krylon machinery grey.

            Here's a link to their website: https://www.por15.com/Rust-Preventive-Coating_c_11.html

            It's some pricey stuff so make sure you're sitting down when you check the prices.

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            • #7
              What are "one-trip 20 foot seacans"? Is that slang for travel-trailers/motor homes?

              I second the phosphoric acid treatment, although I don't know that spraying it on is the safest way, even for such large surfaces. A quick search found the acid available in quantity on the sites below, although I'd check the MSDS for any I considered buying, just to be sure exactly what's in the product. Shipping might be another concern.

              https://www.globalindustrial.com/p/j...yABEgLhXvD_BwE

              https://www.speedclean.com/product/s...5-gallon-pail/

              Loose rust and scale needs to be mechanically removed first. Pressure washing/sand blasting of thin metal should be done carefully, as too much force will distort the metal more. Superficial rust doesn't require either, but cleaning off the remains of paint, dirt and other accumulations would.

              As for painting, the best I've seen is the Rustoleum 9100 series; I've used it for large tanks subject to both mechanical and chemical damage with very good success:

              https://www.google.com/url?sa=t&rct=...EHhKwc7L3aevb_

              If your county has a Toxic Waste program, it may also have a Giveaway operation for reusable materials which have been separated from the true waste ; this may include exterior house paint and even the H3PO4, so might be worth checking into. What State are you in, california? Others have had large fires too, although not as many or as large.

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              • #8
                Yup! A million years ago... or 25ish anyway when I worked at Tool & Supply we had a huge paint department. One of the products we sold a lot of was called Extend. Scrape, sandblast, sand, or whatever all loose rust, dirt and scale away, and then turn the rest into a rust preventative.
                *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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                • #9
                  Aren't containers normally made from COR-TEN???
                  Location- Rugby, Warwickshire. UK

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                  • #10
                    Originally posted by CreakyOne View Post
                    What are "one-trip 20 foot seacans"? Is that slang for travel-trailers/motor homes?
                    I think he means 20 foot shipping containers; the kind that can be hauled on a semi truck and stacked in a ship.

                    OP - rust converter is what you want for a durable coating and minimal prep. It converts the rust to a dark brown or black coating that is tougher and harder than most paint, and protects very well. You can paint over it if desired. The stuff is available to either brush on or spray on, and of course is available in aerosol cans too for smaller jobs.

                    You're supposed to brush off any loose rust scale, but if there's no scale you can just leave the surface rust in place and spray over it.

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                    • #11
                      Originally posted by Yondering View Post
                      I think he means 20 foot shipping containers; the kind that can be hauled on a semi truck and stacked in a ship.

                      OP - rust converter is what you want for a durable coating and minimal prep. It converts the rust to a dark brown or black coating that is tougher and harder than most paint, and protects very well. You can paint over it if desired. The stuff is available to either brush on or spray on, and of course is available in aerosol cans too for smaller jobs.

                      You're supposed to brush off any loose rust scale, but if there's no scale you can just leave the surface rust in place and spray over it.
                      re Seacans: I guess I just had too many other things on my mind; I should have immediately realized that myself ...

                      Many "Rust Converters" are a mixture of phosphoric acid with some type of compatible paint or coating. They work, but for the long term, I think doing the two jobs separately is better.
                      Last edited by CreakyOne; 08-01-2018, 12:01 PM.

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                      • #12
                        Kinda funny actually..... looking at the Penetrol SDS, it may be, as has been suggested, linseed in naptha and ethylbenzene as a solvent.

                        Funny because I suggested diluted linseed a few years back on another forum, and was told in great detail, with references to my probable ancestry and mental acuity, how totally impossible it was for that to work on rust in any way.

                        https://www.loghelp.com/images/MSDS_Penetrol.pdf
                        1601

                        Keep eye on ball.
                        Hashim Khan

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                        • #13
                          I went through the same thing with five of the things. I had to replace floors as well
                          I wasn't about to sand five of them.
                          I pressure washed several times and painted with any paint I got my hands on.
                          Gave them a few weeks and pressure washed the peeling areas again, then repainted the whole thing.
                          It ain't pretty but I have a shop to work out of.
                          And a lot of it came from you guys on this forum and your generosity.
                          Thank you.

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                          • #14
                            I agree with the other posts.

                            Now, for a quick and dirty method. Pressure wash and paint with an industrial coating containing red oxide. I have done it with outdoor metal sheds that I didnt want to prep correctly and it held up very well.

                            Some of the other coatings are very expensive (por) and I have used them and they work.
                            JR
                            My old yahoo group. Bridgeport Mill Group

                            https://groups.yahoo.com/neo/groups/...port_mill/info

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                            • #15
                              I was going to say painting a shipping container with POR 15 would cost about the same as building a house, almost.
                              Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router

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