Caswell Plating

[Patcon]

Can't upload pics. Tried a work around but it posted an empty reply...

Edited July 16, 2016 by Patcon

[Patcon]

This is some of the hardware I plated last week

These large bushings and washers came out really good too...

 

This hinge plate is a little dark but isn't burnt on the top edge like the picture makes it appear

This bar came out really good. Obviously some of these parts are not Z parts. They are off the skid steer I'm working on...

[Patcon]

@Namerow

this is todays effort, more skid steer bolts

started with some bolts with surface rust

bead blasted

Lightly buff them against a wire brush on the grinder. If you use too much pressure it gouges and scratches the part up. If the pressure is light it makes them shiny. Into the crock pot with SP degreaser. RINSE Then I dip them in Muriatic acid for a pickle dip for 20-30 seconds. They pretty much quit fizzing when I pull them out. RINSE

After plating 30 minutes at the calculated .15 amps/in

This is a second batch plated for 30 minutes. I ran these a little higher to try to burn them a little bit

RINSE

 

I bought some blue chromate a few weeks ago. This is what it does. I intentionally dipped them only part way to illustrate the affect

 

This is a 60 second dip in blue chromate

Then I let them hang until dry

Edited July 16, 2016 by Patcon

[Patcon]

This is after the yellow chromate

I dipped the bolts for 25 seconds and the washers for 20 seconds

Then I lightly rinse with a spray bottle. If you get too aggressive you can rinse the chromate off. Shake the excess off. If it puddles and beads it will make dark spots. For things that really matter I dry them with light compressed air to keep them even...

Edited July 16, 2016 by Patcon

[grannyknot]

Looks like you found your stride, I'd be happy with those results.

[Patcon]

Thanks Chris, I am really close to having results as good as the shipment I already had professionally plated. If it doesn't improve from here I will still be happy...

For posterity there are little things that can trip you up:

The metal needs to be degreased before bead blasting or wire wheel work or you just spread the grease around

The shinier the piece is before plating the better it will look when plated

If the metal is pitted it's going to be pitted after plating

There are ways around this but I haven't gotten to that level yet

You need to calculate your areas accurately and use a timer to get consistent results

I know there are some DIY methods for solutions but I didn't feel like trying to reinvent the wheel (that sounds a little insulting but is not meant to be I just have too many irons in the fire already and wanted the path of least resistance). The Caswell chemicals can get expensive, especially if you are dipping larger parts but over all I will break even or probably come out ahead considering I have several cars that need this kind of attention. I prefer plating myself because I can do things in really small batches and not have to loose fasteners or pull together a large order then sort them after plating...

I noticed something today...

I think it was Motorman7 who commented at some point that the yellow chromate finish is fragile when it is new. I found this to be the case today. After an hour or so I was messing with the bolts I plated. I could scratch the yellow off down to the blue chromate with my finger nail. I will let them harden for a few days and see if this persists. I have been letting the blue chromate dry before the yellow because I didn't want to contaminate the yellow chromate. I may have to dip wet to wet for the yellow to adhere properly...

 

 

Edited July 24, 2016 by Patcon

[Patcon]

@motorman7

I went back 24 hrs. later and 7 days later and both times I can still scratch the yellow chromate off with my finger nail.

Rich, How fragile is you completed finish? I am thinking I need to yellow chromate immediately after blue. Do you have any issues with contaminating your yellow chromate with the blue chromate?

[motorman7]

I do the yellow chromate immediately after the blue chromate, so the part is still wet.  When the yellow chromate is done I dip the part in hot tap water then blow dry on high heat with a hair dryer.  This works well for me and often I will install the bolts within an hour or two.  I think the heat from the hair dryer is important in hardening the chromate.  I typically dry the part for about a minute on high heat.

[Captain Obvious]

I know almost nothing about this whole process and I find it neat that you guys are able to do this kind of work.

Is the chromate coating an electroplate process like the zinc, or is it just a paint like coating that "dries"? In other words, when you're applying the chromate, do you run electrical current through the parts, or do you just dip them into a solution and then pull them out?

[Patcon]

The plating tank, where the zinc coating is applied, is the only tank that uses current. The chromate tanks are just a dipping solution but I believe they have an acid base to make the process work...

[hr369]

Some people have baked their newly plated parts in an oven to harden the coating.

You mentioned hydrogen embritlement in the first post on this thread but nobody answered your question.

 

Perhaps this may help?

finishing dot com website

Edited July 25, 2016 by hr369

[Patcon]

I wonder if our application is really that susceptible to hydrogen embrittlement? It looks like 4 hrs @ 375dF for post plating hydrogen removal