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Yellow chromate, whats the secret?

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  • #16
    Re: Yellow chromate, whats the secret?

    Tom,

    Email me and I'll send you some instructions on how my tanks are setup using garden "ridge risers" these are rigid PE tubes and fittings for microspray watering systems. Some are more rigid than others. They still tend to float a bit but not as badly and generally can be set in position.

    mark.smith5@baesystems.com

    Not sure with the silver pass on heating. Mine is a different setup.

    Cheers

    Mark

    Comment


    • #17
      Re: Yellow chromate, whats the secret?

      Wow, I must have the touch?

      I chromate a lot of my pieces and it works great. As soon as I finish the plating I spray rinse with DI and go right to dipping it. Once I have the desired color I pull the part and spary rinse with the same DI. I can handle the part immediately and it's rock solid. The only way to get it off is to use and abrasive. I have none of the issues you guys are seeing.

      I''ll look at the type of chromate I have and maybe a batch number? I got it right from Caswell and have been using the same batch for years.

      Comment


      • #18
        Re: Yellow chromate, whats the secret?

        There are different types of Chromates. I use 2 types.

        Ecopas (local product) is great as it won't "slough" and is hard with in hours if warm, but it is pretty much gold coloured with none of the purple/blueish hues. It will disolve in acidic solutions very quickly even when fully cured.

        Zinmax cant be touched for at least 2 days if left to air dry as it will fall off, but is tough as nails and has the nice blu/purple hues once it has cured. I air cure this for a day then bake at 150 deg C for a hour or so to harden.

        In my gallery pics, the brake callipers are ecopas (45 second dip) and the recent mix of cooper S bits are Zinmax (20 second dip).

        I always hot water dip for about 10 seconds straight from the chromate tank. this part cures the chromate enough to be more forgiving.

        Cheers

        Mark

        Comment


        • #19
          Re: Yellow chromate, whats the secret?

          Update with new setup:

          Yippee!! It works!!

          My issue with Yellow Chromate soughing off is solved. I took the forums advice of using Blue Chromate as an intermediate step between the Copy Cad and Yellow Chomate and it works great, Plus the Blue Chromate is a wonderful product in its own right.

          Here is my process with a 5 gallon Copy Cad pail system with at 25 amp recifier:

          o I prepare the parts by using a 6 inch bench grinder with a fine wire wheel, or for rougher parts, I use the blasting cabinet.
          o I wire the parts with brass picture frame wire to increase the conductivity of the wire. Additionally, I use a small spring for small bolts and a larger spring for bigger bolts. Also, I have bent a few wires to carry washers and bolts. Looks like a continuous "z" with about 10 or 12 places for washers and nuts.
          o I use the Caswell, SP Degreaser heated to 180 degrees F in a three (3) quart crock pot. I rinse the parts on the wires for 20 seconds to get rid of the fingerprints and remaining oil.
          o Then, I rinse in a 5 gallon pail with tap water for 5 seconds.
          o Then, I place the parts in Muratic Acid for only 5 seconds if the parts are rust free, to etch the metal. If I cannot wire wheel very small washers or other small parts, then I will only soak those parts for a max of 20 seconds, as I have found that the Muratic Acid will turn the nice, shiny wire wheeled parts a dark color and all I want to do is etch the parts.
          o Then I rinse the parts coming out of the Muriatic Acid for 20 seconds in the plain tap water pail and then follow that rinse up with a spray bottle filled with distilled water (NEW STEP).
          o Heat the Copy Cad to 90 degrees F and put bandages from Caswell on the anodes (NEW STEP). Personally, I plate for six minutes per side at a very small rate with small bubbles from the nuts and bolts to be plated. I am not smart enough to measure the square inches of the parts to plate. I use the Caswell Copy Cad Brightner too. A tablespoon every four cycles of plating.
          o After the 12 minutes of plating, I spray the parts with the spray bottle of distilled water (NEW STEP).
          o Then I place the parts in Blue Chromate from Caswell for 20 seconds at room temperature and I get the most wonderful, deep, shiny parts from the Blue Chromate (NEW STEP).
          o Then I spray the parts with distilled water (NEW STEP), and place them in Yellow Cromate for 45 seconds. The Yellow Chromate is heated to 80 degrees F.
          o Then, I spray the parts with distilled water (NEW STEP).
          o I hang the parts for 48 hours.
          o I have not baked the parts yet, but I will do that in the next day or two.

          This is my process, and I can tell you that the process has totally eliminated the sloughing issue of the Yellow Chromate and the parts (carb parts in this case) present in the yellow, red and green flowing colors that we all want!!

          This is the process that will not fail you.

          Good luck, Tom

          Comment


          • #20
            Re: Yellow chromate, whats the secret?

            Tom,

            Congrats on your success and thanks for the write up!!

            FYI -- I referbished a very high end golf course greens mower last year with the Caswell zinc system -- double chromate (blue then yellow) on everything. Some of the parts are carb. parts and the machine has been used all year. The zinc and chromate job has held up great!!! There are only a few parts that will need to be replated this Winter and that is because they were in high wear areas and I expected they would need replating. Even in those high wear areas, the chomate conversion coatings were removed by abrasion, but the zinc plating held up and did not expose the raw steel -- which is the ultimate goal of electroplating anyway.

            Anyway, congrats on your success again.

            Comment


            • #21
              Re: Yellow chromate, whats the secret?

              Hi,

              The best thing I can add after only having done one batch is to use Blue Chromate for 45 seconds and then heat to 200 degrees for three hours.

              Good luck, Tom

              Comment


              • #22
                Re: Yellow chromate, whats the secret?

                For the chromating process. The solution should be mixed at 1/2 to 2% by volume and used at 65 to 90 degrees F.Once the parts have been plated and rinsed with distilled water, you should dip in the yellow chromate for 5 to 30 seconds, do a cold water rinse followed by a hot water rinse @150 F, both for about 10 seconds. After these steps you should hot air dry at no more than 170 degrees F. You can use a 1% sulfuric acid etch after plating to neutralize any residual plating solution. before chromating. If you dip the parts into the chromate for a longer period than recommended it will start to eat itself off.

                Comment


                • #23
                  Re: Yellow chromate, whats the secret?

                  First,
                  I will recommend to you for future reference is "Product Finishing.com and Metal Finishing.com". I have been in Metal Finishing for 30 years and believe in "Process Control".

                  1. Chemistry control: Chrome Concentration & pH. If you control solution in
                  it's parameters should not have problems.
                  2. Time follow recommendation from Technical Data. Longer time is at times
                  the worse option.
                  3. Drying time and heat. Chem film also refered to conversion coatings with
                  chrome does not do good with high heat. Try to use about 100-125 F air
                  circulation oven.
                  4. Chromate finish can not be measured!
                  5. Also, just because you do not see the rainbow color does not mean that it
                  has no chromate film.
                  6. How durable is the chromate supposed to be? It's not formualted for
                  hardest or a strong for corrision protect. It has it's limits.
                  7. Does the chromate "harden" with time? Will it be more durable after a week
                  or two? No.
                  8. What are the most common reasons for the chromate NOT working?
                  Chemistry control! Concentration & pH.
                  9. I have seen posts where it was recommended that the acid dip be
                  skipped. The chromate process has been set and any changes will lead to
                  problems with our finish.
                  11. Recommend a predip acid dip before chromating (5-10% Nitric acid).

                  12. Other where it was recommended that one dip for a longer period
                  of time. Follow your technical data.
                  13. Some folks recommened more time flushing the newly plated
                  pieces with distilled water. Recommend but expense!
                  14. Others have recommended tap water. Could effect finish later in time
                  with corrision (Cl or Fl ions in tap water).
                  15. WHAT ARE THE REASONS FOR THE CHROMATE NOT BEING DURABLE? Not
                  formulated for hardeness. Finish is for corrision protection and for under
                  coat for paint.
                  16. More washing time? ?? Do you mean clean base material before
                  chromating?
                  17. More/less time in the acid dip? 6-8 seconds.

                  18. More drying time? Dry for 30 mins or less in air circulating oven.

                  I my experince with chromate finish has been excellent in the Hardware, auto and aerospace industry. The secret is process control for consist and repeatable finish.

                  Nol4154

                  Comment


                  • #24
                    Re: Yellow chromate, whats the secret?

                    Wait...is the yellow sold by Caswell hexavalent ortrivalent? EPi produces both. I don't think the Caswell site provides that info and I've seen both mentioned on the forums.

                    Comment


                    • #25
                      Re: Yellow chromate, whats the secret?

                      Hexavalent
                      --
                      Lance Caswell
                      Caswell Inc
                      http://www.caswellplating.com
                      Need Support? Visit our online support section at http://support.caswellplating.com

                      Please support the moderators on our site by leaving reputation for their helpful posts. Read more here.

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                      • #26
                        Re: Yellow chromate, whats the secret?

                        Thanks. Not to hijack this thread but should one wear a respirator any time the chromate tank is opened? I try to ventilate my work area (harder when it's 25 degrees out) but spend a lot of time working over the tanks and if I understand it correctly, hexavalent chromate is a lot naster than trivalent. Contact (skin) is practially nil but inhalation of vapors is a concern.

                        Comment


                        • #27
                          Re: Yellow chromate, whats the secret?

                          Yellow Chromate.pdf

                          Fumes are minimal because the solution is not agitated at all, but when in doubt, you should always use appropriate protection.

                          MSDS attached.
                          Last edited by lcaswell; 02-14-2010, 12:44 PM.
                          --
                          Lance Caswell
                          Caswell Inc
                          http://www.caswellplating.com
                          Need Support? Visit our online support section at http://support.caswellplating.com

                          Please support the moderators on our site by leaving reputation for their helpful posts. Read more here.

                          Comment


                          • #28
                            Re: Yellow chromate, whats the secret?

                            Thanks, but attachment no worky.

                            Comment


                            • #29
                              Re: Yellow chromate, whats the secret?

                              Fixed now.
                              --
                              Lance Caswell
                              Caswell Inc
                              http://www.caswellplating.com
                              Need Support? Visit our online support section at http://support.caswellplating.com

                              Please support the moderators on our site by leaving reputation for their helpful posts. Read more here.

                              Comment


                              • #30
                                Re: Yellow chromate, whats the secret?

                                And speaking of "Yellow chromate, what's the secret?", I have not had a problem with durability since I "got it right" last year. I have read the forums throughly, trying to follow every tip and keep the plating system as tightly controlled as possible and it seems to have paid off. I rarely have sloughing or any issues, so long as everything is done correctly.

                                That said, I want my items to have to most durable finish possible. Is the general consensus that the parts should be heated after they've air dried? I haven't been performing this step since I first tried it and the chromate changed to a darker (less favorable) color...I think the temperature might have been too high.

                                Since then, I just used compressed air to remove all water, then hang them to "cure" for a day or two.

                                Thanks!!!

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