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recommended bath concentration for 12A/ft^2 current density

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  • recommended bath concentration for 12A/ft^2 current density

    I want to try out some 12A/ft^2 anodizing, mainly because it will be faster, and was wondering what electrolyte concentration to use to obtain a pore size favorable for dyeing. Thanks!

  • #2
    hey, what caswell used before for the HCD anodizing was 1:1 of battery acid and distilled water. this worked out to be more specifically 25% sulfuric acid. the high current is what im using right now.

    have you had any luck with figuring out your problem?

    i found my problem was using dyes at room temp (which works fine for me) but out in the garage room temp this time of year can be too low.

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    • #3
      Battery acid in a 1:1 mix with Distilled water is actually 17.5% by weight (or 9.5 by volume), not 25%.

      If you're dyeing at under 110 degrees, you are extremely lucky that it is being absorbed at all. Room temperature is not the temperature of any room you happen to be in. Typically it is a range of 65-75, but I wasn't aware that any of Caswell dyes were recommend for use at room temp. In any case, I'm glad you got your problem resolved.

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      • #4
        i know im going off topic here, and i apologize to neomoses for hi-jacking his thread

        ive read from published sources that cold dyeing (room temp 65 - 75) produces very good results that are superior in color depth and brilliance to 'zapping' the part with hot dyeing. i would otherwise agree with caswell were it not for my own fine experience with room temp dyeing. that and buying 14 heaters is not an especially appealing notion. you should try it at room temp once or twice, see how you like it.

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        • #5
          No problems, potsked. Your answer to my question was exactly what I was expecting.

          I'll also agree with potsked on the room temp dyeing. It works quite well, although it might be a bit slower than dyeing with warm dye. However, seeing as how LCD takes about 90 minutes to anodize, another 15 minutes to dye doesn't bother me.

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          • #6
            Thanks guys, the 1:1 acid:water mix is working quite well with constant current anodizing at 12 A/ft^2. I've only done a couple of batches, but it's looking like this will only take about 45 minutes per batch, a definate time saver.

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            • #7
              Why would you want to do this when we have a MUCH better system. OK it's slower, but SO MUCH MORE RELIABLE

              PLEASE change over to the LCD system. We aren't giving tech support on the old method.

              http://www.caswellplating.com/kits/lcd_ano.pdf
              --
              Mike Caswell
              Caswell Inc
              http://www.caswellplating.com
              Need Support? Visit our online support section at http://support.caswellplating.com

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              • #8
                Why would you want to do this when we have a MUCH better system. OK it's slower, but SO MUCH MORE RELIABLE
                Being a mechanical engineer, I'm an incessant tinkerer at heart. I have 2 tanks, one LCD and one 'test' tank. Don't get me wrong, I'm a huge advocate of the LCD system; it is very reliable and inexpensive.

                My goal with all of this is 100% understanding/mastery of the anodizing process.

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                • #9
                  did you ever figure out that resistance problem? im using ye olde High Current Density method for now, until you figure it out (yeah im lazy, real lazy)

                  i read a post a little bit ago that referred to very similar voltages and currents that you and i were experiencing.

                  hope you figure it out, good luck

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                  • #10
                    Originally posted by potsked
                    did you ever figure out that resistance problem? im using ye olde High Current Density method for now, until you figure it out (yeah im lazy, real lazy)

                    i read a post a little bit ago that referred to very similar voltages and currents that you and i were experiencing.

                    hope you figure it out, good luck
                    I think my problems were with my black dye, which had been left out, exposed to the air for a couple of weeks. I don't see the same problems with other dyes or the new black that I mixed up.

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                    • #11
                      Neomoses,
                      Recall that you can use PAR detection at 12A/sq.ft, or any other current density. The value of PAR will be a little higher than 2.5 Ohms/sq.ft., the peak will be very pronounced and hard to miss. You will need about 30 Volts peak, anodization time should be around 15 minutes. Your agitation system will really earn its keep, since power dissipation in the electrolyte will now be a concern.

                      Is 30 Volts peak and 15 minutes anodization time what you are seeing?

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                      • #12
                        12 amps a sq foot is what caswell was advocating before you came along, and they suggested anodizing for around 45-50 minutes.

                        im not really sure how much current is going into the parts, but from others i know that chargers usually put out 10 amps a sq. foot.

                        crude as it is, i still find the let it rip method adequate for now.

                        Comment


                        • #13
                          Originally posted by Fibergeek
                          Neomoses,
                          Recall that you can use PAR detection at 12A/sq.ft, or any other current density. The value of PAR will be a little higher than 2.5 Ohms/sq.ft., the peak will be very pronounced and hard to miss. You will need about 30 Volts peak, anodization time should be around 15 minutes. Your agitation system will really earn its keep, since power dissipation in the electrolyte will now be a concern.

                          Is 30 Volts peak and 15 minutes anodization time what you are seeing?
                          That's not really what I saw with this batch, so I chose to let the parts go for 45 minutes (my old method) instead of detecting PAR.

                          Instead of seeing the distinct peak like you did within the first 15-20 minutes, my voltage:time curve looked much like the 4.5 A/ft^2 curve for LCD with a quick rise to a certain voltage and then a nearly constant voltage for the remainder of the time. I believe that the more concentrated bath may have something to do with this, and I'm not going to speculate too much since I have only done 1 real batch with this method. Over the next few weeks, I'll anodize more parts in this bath (for now, let's call it the SCD or Standard Current Density Bath). I'll try to keep better logs of voltage and post them when I get more trials completed.

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                          • #14
                            Originally posted by potsked
                            12 amps a sq foot is what caswell was advocating before you came along, and they suggested anodizing for around 45-50 minutes.

                            im not really sure how much current is going into the parts, but from others i know that chargers usually put out 10 amps a sq. foot.

                            crude as it is, i still find the let it rip method adequate for now.
                            Guys, can we just let this rest for now? Old Timers, can we just suffice to say that the old method can (and still does) work, although it may not be the best solution for a beginning newbie?

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                            • #15
                              OK.
                              Post your data when you're ready.

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