SeanR

Here's one for the experts.

Brad had a bunch of misc parts taken to a plating company and had them do what they do. Upon pick up, all the nuts/bolts/clamps looked fantastic, but when it came to the larger parts that were sent, they looked like ****.

What would cause some parts to look good, and others to look like they sprayed them with gold spray paint? Here is an example, two fuel rails, one good, one bad, and the A/C heat shield.

I don't know the process used, Brad will have to chime in about that.

jleidel

did they not heat them evenly during curing?

Giovanni

What did the plating company say?

a4sfed928

The dull parts were bead blasted ???

SeanR

That was my first thought. The issue with that is, the parts were delivered clean. Not perfect, but good enough to have been dipped and then plated.

Landseer

I think electrical setup / proximity of stuff to the sacrificial metal in the tank is important, line-of-sight or something like that.

ALKada

These links might shed some light on the process and why the parts did not turn out consistantly.


http://www.ehow.com/list_6390022_zinc_chromate_plating-properties.html
http://en.wikipedia.org/wiki/Chromat...ersion_coating

It might be in the color step in the process...

Rob Edwards

Greg has had his place do 3 batches for me, with highly variable results. The nice thing about ****ty results in Greg's shop is that he tapes on his scary biker mustache and beard and goes over there and asks that the pieces get re-done for free. And they do it. The second time is usually a charm.

Brad's place oughta re-do the pieces that didn't work for free.

As to why the big pieces didn't work, I'd guess that one of the plating solutions was old, so not enough metal was deposited on the pieces with larger surface area. I bead blasted all of my pieces first, so that's not why it has that etched look (unless they did it with something really aggressive at 120psi....). There's probably a better explanation in the posts on Caswell's user forum.

http://forum.caswellplating.com/elec...ing-questions/

BC

I agree with Rob. I have had alot of stuff plated, and it seems like that crap stuff is low deposit.

karl ruiter

I plated all the hardware on my last motor myself. There are two issues I saw that would make the zinc come out dull. The first was too little plating current. I was suprised by this and would have thought that a slower plating process would come out brighter, but it was the opposite. Note that the total amount of current you need depends on the surface area you are trying to plate, so if you get impatient and try to plate too much stuff at the same time for the current you have avaialble it comes out dull. Or if you don't have good electrical contact to your parts or electrodes and don't watch your current meter it will come out dull. The other was that there is something you have to put into the plating bath called 'brightener' that evaporates over the course of a few days and has to be replentished regularly or it will come out dull. The good news is that starting over is easy. 10 minutes in battery acid and the parts will be back down to bare metal.

Brad W

Like Sean said, all the parts were clean and ready for the process tanks. It looks like they sand blasted all the parts. I started to wire wheel one of the parts and the pitting was horendous. There was zero pits on all the stuff and some could have passed as new before going to get plated. Now it looks like I will be buffing and replateing all the parts. Some of the parts still had grease on them. So my thoughts are a qick heave blast and then into the tanks. In my opinion they ruined all my fuel rails and big parts

karl ruiter

Brad, are you sure the pitting is in the steel and not just in the zinc? As I mentioned, a few minutes in battery acid will pull the zinc right off and leave the steel.