Yellow Chromate & Copy Cad

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Hi. I had the kit for about three weeks now, it is still awesome. Have absolutely no complaints, praise only. However, I was under an impression that Yellow Chromate will dye even commercially obtained zinc plated items. I tried to "yellow" some nuts and bolts from a local hardware store, the color seems to be right, but the yellow finish can be rubbed off with a shop towel (24 hours later)! The items were properly degreased and I tried some battery acid on them, zinc reacted very rapidly. What am I doing wrong? I must note that my freshly plated parts accept Chromate well and finish seems somewhat durable, still VERY easy to remove the yellow coloring with steel wool. My chromate solution is applied for two minutes at 22 deg. Cel. Thanks.
Andrew.

[mcaswell]

You might want to try freshening the zinc plate on your store bought parts with the plating kit, then chromating them.

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That's what I did, will let you know when the parts dry out.

[newman]

i too am having a hard time getting the yellow chromate to hold, right after i zinc plate i rinse with water and dunk into chromate for about 1-2 mins ,after 2-3 days i can remove all the color off with water and a rag, im running the bath @80%.... any ideas how to resolve this?
would a Nitric Dip help right before chromating?

thanks .

ps: im zinc plating old carb castings from the 60s.