Fresh copy cad system leaving white swirls

[KCV6]

If you are gold chromating the parts, this should be done before letting the parts dry. Any chromate finish should immediately follow zinc plating. I always chromate as follows:

1. As soon as the zinc/copy cad (they are the same thing) is covered to my liking (usually 10 to 15 mins max), remove from tank and rinse in zinc rinse tank or bottle rinse.

2. Straight from rinse to 0.5% nitric acid bright dip. Even if my tank is getting real cloudy and due for a good filter and the parts have grey marks in them the 0.5% nitric dip for 10 seconds always brings them back to bright silver zinc. I don't agree with hydroclauric 10% dip. This mix is for stripping zinc or activating steel. Always bright dip in 0.5% nitric or 5 to 10% sulphuric.

3. Straight from nitric dip to bottle rinse and then to 15-30 seconds in chromate depending on how dark I want them.

4. Straight from chromate to bottle rinse then 15 seconds in hot tap water in a bucket to seal the chromate, then final bottle rinse and let dry for 2 days before handling.

OK clarification on a few things. for every one of my tanks I have a distilled/RO water tank of the same size for rinsing my parts as they come from the tank. As the tank gets low, I fill from the rinse tank and then top up the rinse tank with distilled/RO water. This means you are not loosing chemicals from dragout. they eventually cycle back into the tank. The other advantage of a rinse tank is if you are interrupted and have to go do something else for a while you can just leave the bits hanging "wet" in the rinse tank, this will prevent them from oxodising.

Bottle rinse is just a cheap spray bottle full of distilled/RO that I use to final rinse after chromating or hot tap water rinsing to remove the **** in the tap water which will stain the chromate.

Other handy things to have but you can get away without them. A hot air gun as previously discussed and a small electric toaster oven. after 2 days hanging I relief most of my bits at 200 deg C for 3 hours in the toaster oven.

drop the 10% hydroclauric acid dip post plating and substitute with either nitric or sulphuric.

Cheers

Mark

[seanc]

Originally Posted by MrPontiac

Sean, all im doing is copy cading parts. Then using yellow cad system, works super on the yellow, no problems at all, Still cannot figure white streaks out??

Are you clear chromating the non-yellow pieces?

Totally a lose on the green drab though, nothing at all is happening with that system.

Sorry, can't help with that. I've never used the green drab.

Sean

[MrPontiac]

Still using my hair dryer, not helping all that much

[KCV6]

When are you drying? Are you going straight to the chromate after plating or drying the part first?

As Sean has said, natural zinc/copy cad will rust (white rust) if it is not protected by either a wax or a chromate finish imediately after plating.

Cheers

Mark

[MrPontiac]

Chromate to drying immediately with hair dryer, still happening, its really a shame the parts look great as soon as they come out of the electrolite tank,within a minute or so you can see the white swirl marks starting to come on,really don,t see it on the round parts im doing but the flat parts look grappy. I did try dropping the temp by 15 degree,s it may of helped somewhat but not much.