Yellow Zinc vs CAD

Both are 'sacrificial' coatings with cadmium being the more preferred as the product as the effects of the corrosion are more prevalent with the zinc and the byproducts not desirable. Cadmium withstands slightly higher temperatures also 400+ deg vs 250 deg for zinc. They'll both eventually look crappy again just a matter of time.

 

Would also consider the quality of the zinc being done. Every gold fastener on the car is zinc and if the many years old fasteners aren't far worse the replated zinc you have a problem with your plater. I have had a lot of parts plated in yellow zinc and have never had a complaint like this.

I am no plating guru but I understand there are 3 or 4 different types of zinc plating. It may be yours was less element tolerant than others. But it seems cad is better for salt exposure than any of them.

Good platers are going the way of the Dodo bird fast. It is an industry dyeing before our eyes. Good quality work is rapidly diminishing.

 

I would just like to bring up one potential point in this case.

It could have been your zinc was not applied heavy enough or thick enough.

But yes in general cadium is "better/stronger" it can also be very toxic as well due to lead and mercury content

 

Agree...

Although the Hod Rod and Harley guys seem to find them.
For chrome any way...

 

They're still out there but fewer and fewer. It is an environmentalists worst nightmare. Lots of it going south of the border.

 

Prep work of the hardware is the key to a good long lasting finish.

 

And to saving a bunch of money, if you do it yourself ;-)

 

Dosent one of these proceses make the metal brittle.

 

Yes. I have spent hours in front of a wire wheel cleaning nuts and bolts..it sucks. But it needs to be done. I have since invested in a tumbler which I turn on at night before leaving the shop. In the morning the hardware is nice and clean..rust free and ready to go to the platers.

 

Yeah, I spent a day cleaning nuts and such on a wire wheel. Tumbler makes perfect sense if you are doing it regularly.

 

Yes hydrogen embrittlement. Both plating processes can cause it so the parts must be baked immediately after plating to diffuse the hydrogen out.

 

What's a good medium for tumbling parts prior to replating?

 

Was told If the part is not baked immediately after. you can still get hydrogen embritlement.

 

So hard to find good platters, silver paint?

 

As you know, way too much work and the results are far from ideal as wire wheels don't get into the tinny areas, etc.

Hydrogen embrittlement is a concern with hardened parts - not soft, such as mild still brackets. This is why it's very important to use a plater that is not some garage dude Also, the higher strength (hardness) fasteners require mechanical plating - not electroplating

I glass bead blast first - it removes all prior coatings and corrosion. I then finish off tumbling in plastic media. Here are some before and after followed by yellow zinc
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I used to work in a factory where we used to make ejector seats for the military, some of the parts were Cadmium plated and if i remember correctly this has a grey finish- as it was toxic they then carried a Passivation process by dipping it in some other solution to seal the Cadmium in.
Net result, the finish was a golden colour.
One of the men in the plating dept caught his hand on 1 of the spikes they hang the parts on, just a small puncture in his hand but Cadmium posioning and months of treatment trying to get it out of his blood.
Its the final Passivation that gives the final colour

 

That's "white rust" - and I guess the plating qualities/thickness will get you the number that reflects how long it can resist salt spray before rusting. ie. 90 hour salt spray vs. 300 or whatever.. One of those home "Caswell" plating kits will probably get you the look, but not the protection.

Interesting information on this site: Corrosion Resistance of Zinc Plating - Sharretts Plating Blog


Interestingly, few (if any) parts that can be exposed to the environment are yellow cad/zinc plated anymore. There are better plating options available, they just don't original.

 

I'm thinking of buying the Eastwood cad look painting kit. I've seen some pieces done with it and they look pretty good. Might even last longer and can be easily stripped and redone if that's your thing.

 

I'd say that's a bad idea. Paint has thickness - zinc plating does not (or so minor you probably can't measure it)

 

I had an Eastwood kit......parts looked good for only a short time...thru it away!

 

I was warned that glass beading would dull the finish but if it made any difference I didn't notice it. I think I used well worn glass but it cleaned well and the parts looked great after plating. Using glass is easy enough but if there's a tumbling medium that works without the need for glass beading my lazy side is interested.

Do you think that tumbling in plastic after glass beading changed the appearance of the final finish?

 

What size/type media are you using in your tumbler?