Plating technics - NCRS Discussion Boards

Plating technics

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Rob M.
    NCRS IT Developer
    • January 1, 2004
    • 12695

    Plating technics

    Hi all,

    I suppose that since this is a restoration related forum questions on the aspects of restoration should be considered on-topic so hereby a question about zinc plating.

    What is the best preparation before metal is plated?

    I've just bought all the needed bits for zinc plating (salts, anodes, adapter, preparation salts, wiring, clips, etc.) and setup the set. But when I try it out with a piece of scrape metal the zinc don't seem to attach evenly over the service and also turns dull dark gray. I've slightly polished the metal before I started the plating process and degreased and prepared it with some special salts which was provided with the set. I made sure the used voltage is not to high (1,5 volts for appr 4 square inches of metal) and allowed it 1 full night (12 hours) to plate. After plating I rinsed it of with water and fixate it with another supplied fluid.

    Any additional tips and recommendations out there to get a perfeclty even and shiny zinc layer on my experiments (before I throw in the real Corvette stuff) ?

    greetings,
    Rob.




    Attached Files
    Rob.

    NCRS Dutch Chapter Founder & Board Member
    NCRS Software Developer
    C1, C2 and C3 Registry Developer
  • Jack H.
    Extremely Frequent Poster
    • April 1, 1990
    • 9906

    #2
    Re: Plating technics

    First, the ultimate sucess of plating (glad you found stuff locally, Rob) lies in the surface cleanliness to start with. 'Pickling' a part to remove prior plating, dirt/grease is a good start and, depending on the part, media blast + wire wheel polish with a FINE wheel prior to plating can be even better.

    From a Rocky Mtn Chapter Tech Session a few weeks back where we toured the facilities of a local Cad plating shop (Aero Propeller), here's some of the techniques they use:

    (1) Clean/prep and hang parts in the plating tank.
    (2) Turn the variable voltage up to 3 VDC.
    (3) Bump the current up in 2-3 discrete 2-minute intervals so as not to 'shock' the part and stop 'bumping' the current when you JUST start to see random bubbles forming on the target part surface.
    (4) Let 'er sit in the plating tank for about 25 minutes total, then remove and rinse.

    From what you showed, I think you were in the bath TOO LONG. But, if you LIGHTLY buff the finished surface with a FINE wire wheel/brush, I'll bet it'll gleam like new (despite the surface pit you didn't get out via part prep).

    The trick is coming up with a process that eliminates/minimizes post-plating secondary operations (buffing). Some parts have curvilinear surfaces making it hard to uniformly buff the part out without 'burning' through the plate to get down into the crevices.

    Another trick the plater showed us is to use a light wire wheel or very fine steel wool to post-plate buff. Then, re-hang the part in an active plating tank for a manual count to FIVE (about 5 seconds). This trick was used to improve the final surface finish on parts with pit, bubbles, or individual 'spots' that didn't originally plate uniformly....

    Comment

    • Rob M.
      NCRS IT Developer
      • January 1, 2004
      • 12695

      #3
      Re: Plating technics

      Hi Jack,

      Thanks for your response. I've just bought a 2nd hand high percision power supply with both voltage and current control (and readout) so I should be able to control the process now a bit more...

      the increments you mention in bullit 3 arer these in Amps ? (sounds a bit high to me). Or do you mean ad 2-3 volts at the time ?

      My second experiment (see photo) was done at 1,5 volts for appr. 6 hours. I think still to long and maybe not enough voltage. I sanded the part with very course sandpaper in advance and wet sanded it again after plating and fixation. Still not as it should be so I think I should experiment a bit more...

      All input and suggestions are more than welcome before I throw in my hood support and hood brackets (for the real thing)...

      greetings,
      Rob.




      Attached Files
      Rob.

      NCRS Dutch Chapter Founder & Board Member
      NCRS Software Developer
      C1, C2 and C3 Registry Developer

      Comment

      • John M.
        Expired
        • January 1, 1999
        • 1553

        #4
        Re: Plating technics

        Rob,

        The real key to controlling the plating process is to control the current and let the voltage do what it may. The voltage is irelevant since it will change as the need for current changes. (E=IR)
        Depending on which chemistry of Zinc plating setup you are using, a current of 25ma to 70ma per inch of plated should work well. Generally speaking, higher currents yield brighter surfaces, while lower currents yield duller surfaces. however, too high a current will tend to bubble the plating, and you will see kind of a black edges on the part where the current is strongest. It will look like the plating is burned fight on the edge. This is a sure sign that you are using too much current. I found a industrial DC power supply on Ebay that allows me to control the current by just setting a knob, and that made my plating much more repeatable.
        Agitation is absolutely required to achieve bright surfaces right out of the tank. I use a fountian pump in my tank that moves a lot of water and really keeps the solution moving. I have seen a lot of people reccomend using an aquarium air pump and air stone to agitate the solution, but all this does is make a layer of foam on top of the tank which makes it real hard to see what the parts are doing. Every chemistry of Zinc plating solution has a brightener additive that will make the parts really shine, but make sure that you are using the correct brightener for your chemistry. The additive for a chloride based setup is completely different from one for an alkaline setup, ask your supplier. All brightners are consumed by the process, so you will have to add small ammounts on a regular basis to keep the parts bright.
        Jack is absolutely correct about cleaning the parts! Blasting the parts with glass beads is not sufficient to assure a nice job. A lot of these old parts are Cad plated and not zinc plated, and the two metals are not compatible in the plating tank. I allways remove ALL traces of the old plating with muriatic acid before plating the parts. The acid removes the plating very quickly whether it be zinc or Cad. You will see the parts bubble srongly when you put them in the acid, and when they quit bubbling, the plating is gone. If you fail to remove the cad, you will contaminate your solution and eventually the new zinc will start blistering off after a couple of days.
        Jack is also correct about the ammount of time. A proper setup should be able to plate a part to correct thickeness in no more than 20 minutes.
        Keep in mind that the plating just follows the condition of the underlying surface. If the surface is rough the final plating will be rough, and if the surface is polished to a mirror finish, the finished plating will look like it is polished. Glass beaded parts will look like they have been glass beaded, and the plating will not cover that texture unless some addiional polishing steps are take, either pre or post plating. A lot of parts on these old cars were not bright to begin with, so you need to keep that in mind a vary your technique to get the look that you need. Many of the parts on C1 cars had a light gold dichromate finish to them, while many did not. The dichromate rinse is a very easy process, but is very time sensitive. 2 seconds too long in the dip, and the parts will be too dark gold! This is something that only experience will help. I reccomend that you keep a notebook and write down all the details of exactly how each batch is processed and the results. This will be invaluable as you try to perfect your plating technique. The learning curve is steep, but it is a short one if you learn from your mistakes.

        Regards, John McGraw

        Comment

        • Rob M.
          NCRS IT Developer
          • January 1, 2004
          • 12695

          #5
          Re: Plating technics

          One more experiment, now with 4,5 volts for appr. 20 minutes, pre sanded, rinsed in water and prepared with the special preparation salt and rinsed again (left side plated):




          Attached Files
          Rob.

          NCRS Dutch Chapter Founder & Board Member
          NCRS Software Developer
          C1, C2 and C3 Registry Developer

          Comment

          • Rob A.
            Expired
            • December 1, 1991
            • 2126

            #6
            Re: Plating technics

            Rob,

            I have a simple plating kit from Eastwood. It sounds like yours is much better quality. Anyway, I use what I think is 00 steel wool to polish my parts after plating to get the desired brightness. For me, I'm just replating small items, bolts, etc., that have become surfact rusted. I don't want them to stand out as obviously replated, so I just buff them slightly with the steel wool. However, If I choose, using the steel wool I can polish them to a fairly bright finish.

            Comment

            • Rob M.
              NCRS IT Developer
              • January 1, 2004
              • 12695

              #7
              Re: Plating technics

              Hi Rob,

              The set I'm using contains of the following components:

              Power supply: Current controller: Preparation salt: Plating bath: Fixation bath:
              greetings,
              Rob.
              Attached Files
              Rob.

              NCRS Dutch Chapter Founder & Board Member
              NCRS Software Developer
              C1, C2 and C3 Registry Developer

              Comment

              • Gerard F.
                Extremely Frequent Poster
                • June 30, 2004
                • 3803

                #8
                Rob, here's my workhorse for both

                cleaning and finishing:


                Just a drill in a vise with a blue (medium soft) Nylok wheel. I'm using the Caswell system for zinc (copy cad)and here's how I do bright zinc parts.

                1. Pickle it in Muriatic (cut 1 to 2) to get all rust off or etch the old zinc plating. (you could also beadblast or both).

                2. Then use the Nylok wheel and bring it a bright shiny finish.

                3. Then cook it in your degreaser (five minutes). I now use TSP in a crockpot, and have used Caswell SP degreaser.

                4. If the part dulls up in the degreaser, dry it and buff it again. Always wear nitrile gloves in handling the part prior to plating. After rebuffing, do a short dip in the degreaser.

                5. Prior to plating, do the water test. Spray the part with distilled water, if it sheets over evenly you're OK. If it beads up or is uneven go through the cleaning process again.

                6. In plating with a power supply, adjust your volts up (4-6Vmax)and amps to 0.
                then adjust the amps up until you see a light effervescence on the part. Then lower your volts maintaining the effervescent. (The volts will probably automatically go down.) Zinc takes a lot less voltage then cad, the voltage I have measured across the tank (anode to cathode)is usually in the order of 1/2 to 1 volt. If over 1 volt you might be plating too fast and getting an uneven plating thickness. Lumpy plating at edges closest to the anode. A lower voltage and lower amps will give a more even finish. I usually plate for only 30 minutes, but your system may be different.

                7. If the plating is dull and looks even, then dry it and buff it to a bright finish. Caswell makes this Zinc Brightener which is added to the plating solution, but I find that buffing works just as well.

                8. If you want to keep the bright zinc finish then you need to protect it as zinc corrodes rapidly. You might try WD40, Triflo, light oil, or a clear coating.

                I looked at your pictures and I think your parts were not sufficiently clean, you are using too much voltage, or you have contaminants in your plating tank.
                I'm sure you used distilled water for the plating mix, but any iron, cad or copper in the plating solution will give you dark spots. Make sure your copper hanging wire for the anode is not in the plating solution.

                Too much voltage can also cause uneven plating and dark spots.

                Good Luck and have a Heineken on me.

                Jerry Fuccillo
                #42179
                Attached Files
                Jerry Fuccillo
                1967 327/300 Convertible since 1968

                Comment

                Working...

                Debug Information

                Searching...Please wait.
                An unexpected error was returned: 'Your submission could not be processed because you have logged in since the previous page was loaded.

                Please push the back button and reload the previous window.'
                An unexpected error was returned: 'Your submission could not be processed because the token has expired.

                Please push the back button and reload the previous window.'
                An internal error has occurred and the module cannot be displayed.
                There are no results that meet this criteria.
                Search Result for "|||"