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Originally Posted by bpu699
WHAT ARE THE REASONS FOR THE CHROMATE NOT BEING DURABLE?
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BRIGHTENER! DO NOT USE IT w/parts to be yellow chromated.
I have found that yellow chromate is not as durable on bright plated parts. Others here say otherwise, but I get far better durability on parts plated w/out the "brightener".
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Chromating for 3 seconds or so (what the manual states)
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I don't know which manual you have, but mine states 30 - 60 seconds. 3 seconds will do virtually nothing (it's probably a typo).
Immersion time will depend on the finish you're after. Shorter times result in lighter yellow w/more iridescence, longer times result in darker yellow w/less iridescence. The strength of mix also results in different depths of color & iridescence. You just have to experiment to see what gives the results you're looking for.
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Is it supposed to wipe off when wet?
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Yes. Fresh chromate is quite soft and will rub right off. It has to be given time to cure.
I have also found yellow chromate to be UV sensitive for up to 48 hours after chromating. I leave yellow chromated parts to cure for 4 days in shade before handling.
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How durable is the chromate supposed to be
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When done properly, it is very durable.
As for acid bright dips, it is not
really necessary if you chromate immediately after plating, but does help a bit. All chromates are acid based to begin with, so are in effect "self brightening". A pre-chromate bright dip does still improve the look, but only slightly.
Yellow & clear chromates are nitric acid based, black chromate is sulphuric based. Use only nitric or muriatic bright dips for yellow/clear, and only sulphuric for black.
You only need to dip the parts until it stops brightening. You will be able to see it changing color, when it stops changing, that's enough. How long it takes depends on the type & concentration of acid.
DO NOT LET the parts dry at any time between plating & chromating! Do it quickly & keep them wet at all times. As KCV6 said, if it's allowed to dry before chromate, then you must reactivate in an acid dip.
Sean