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rust resistant surface treatments

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  • rust resistant surface treatments

    Are there any etching or perhaps quenching processees that can be done to steel in order to give it some rust protection? Something that will not easily scratch off is desired. It is also of interest to discuss treatments by metric of their abilities to preserve previously existing heat treatments on the pieces in question.

  • #2
    You have three basic choices:

    Film coatings; Paint, clear varnish/laquer/acrylic, <added> powder coat
    Conversion coatings; Black Oxide, Chromic acid, cold bluing, browning
    Plating; Copper, Nickel, Chromium <added> zinc

    The easiest of the plating coatings is copper as it doesn't require any alkaline cyanide based baths. It can be done using weak acid solutions and easily obtainable copper sulphate.
    Last edited by Evan; 09-23-2010, 10:03 AM.
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    • #3
      I think Evan has covered most of the possibilities with his list. However, I would like to add two comments:
      1. By far the easiest and cheapest treatment for steel is to heat it to red heat and then quench in oil. This give an attactive black surface that has good abrasion and rust resistance. Any oil will do including used engne oil, or used cooking oil. It does destroy any heat treatment ofthe part.
      2. Copper plating is eay and simple to do but it does not provide good rust resistance. On the copper is scratched through on a corner then the underlying steel is exposed and galvanic action between the copper and the steel will actually encourage the steel to corrode. A much better coating for steel is zinc plating. This is just as simple to do as copper plating but has the advantage that the zinc plating cathodically protects the underlying steel if the coating is scratched through. This is why steel is commonly galvanised (zinc plated or coated) for outside use.


      • #4
        I've found that I can get really good rust protection by polishing the item. The reason this works, as I have been lead to believe, is that polishing seals or removes the microscopic fissures so rust has no locations to propagate from. A coating of furniture wax or a squirt of two of some Bosheild will add to that protection and allow intermittent moisture exposure. Of course polishing is time consuming and is not practical for all items so your mileage may vary but I have done it many times on smaller items with very good results.


        • #5
          I can't believe I forgot zinc. Too familiar I guess. I do also find that polishing works remarkably well and I think it is simply because of the reduction in surface area and the ability of the polished item to shed water. Also, most polishing agents are suspended in wax and that wax is left behind in the remaining microscopic crevices and cracks in the surface.
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          • #6
            If you're looking for something that will protect metal while it is in storage Kano Laboratories (same people who make Kroil) have a brush on product that is very effective.


            • #7
              I'm suprised no one mentioned Parkerizing, it is a conversion coating of Zinc or Manganese phosphate. Requires a bit of equipment, but is easy to do.


              • #8
                Originally posted by Steve Steven
                I'm suprised no one mentioned Parkerizing, it is a conversion coating of Zinc or Manganese phosphate. Requires a bit of equipment, but is easy to do.

                And Kibby did a great thread on parkerizing called Let's Parkerize Something. I liked it so much that I copied and pasted it to my files so that some day, if I ever get around to it, I would like to try it.

                Let's Parkerize Something



                • #9
                  There are complete instructions in the reference section of my gallery on how to do black oxide.

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                  • #10

                    I have been parkerizing for several years with the same home made stainless tank that is similar to Kibbys. Mine is a bit bigger.
                    I heat with a old Turkey Fryer propane burner I picked up at a yard sale for $5.
                    I have used the same zinc solution to park about 20 guns and it still works the same.
                    Holds oil very well and stops rust.
                    It's also very durable.
                    Here are my latest guns bead blasted and Parkerized last week.

                    My grandson made the knife so we put it in the tank while the solution was hot.
                    It's mild steel and came out lighter.
                    I cut it off twice and it's still too short!


                    • #11
                      Zinc electroplate is hard to beat for carbon steel of any alloy. If scratched the neighboring plating protects the exposed metal to some extent. There are electroless dips available.

                      You don't want to galvanize any work damaged by 1000F heat and the preliminary pickle.

                      For pure home brew convenience I use Jasco metal prep solution. Scrub the item thoroughly in kitchen cleanser (I use Comet) to remove the oil and residues then dip the article in the metal prep for a couple of hours. Scrub the surface smut off in soap and hot water with a soft bristle brush. Immediately apply any light oil. The metal will be darkened but in my experience the protection is good for a winter out doors.

                      A pro version of this is called "Parkerizing" Google it. It's a process you can do in the home shop if you don't mind the mess and chemicals and the finish is a handsome crystaline black.
                      Last edited by Forrest Addy; 09-23-2010, 05:44 PM.


                      • #12
                        This is a great thread; concise and to the point.


                        • #13
                          If your more concerned with rust prevention than looks, there's a spray paint called Zinc Rich that is, predictably, very high in zinc. I think I've also seen it under the name 'Cold-Galvanize' or some such.

                          Sure, it doesn't look as nice as a well polished surface, and it's not as durable as real zinc plating, but it's as easy as spraypaint and I've had fantastic results with it on things left outside.

                          Zinc Paint vs Hot Dip Article


                          • #14
                            Cold blue is almost purely decorative. It does very little to prevent rust.
                            Hot blue isn't a particularly good rust preventative either, as any gun owner knows -- you have to keep the gun oiled to prevent rust.

                            Of all the conversion coatings available to a HSM'er, parkerizing is, by far, the most effective in preventing rust.
                            "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."


                            • #15

                              I took your black oxide .rtf file and merged it with the black oxide jpg's into one 6-page pdf file, here: