Remove rust (without using abrasives).

[Little Dog]

Inspired by @philward 's scribings, I purchased a zinc/nickel plating kit from Gateros (something I've looked at many times over the past couple of years, but never flexed the card for), grabbed a couple of brackets from my A2 as a learning subject...

View attachment 39877

....and set to. First off, getting them prep'd. Brushed of the crud and flaky rust, then into my version of 'The Skanky Bucket'

View attachment 39878

Never mind chemistry; to me, this is alchemy. As someone who never even did CSE chemistry, it's a Whole New World. I wouldn't be doing this without your guidance Phil. Many, many thanks

A couple of queries: What effect does the amount/concentration of oxy-cleaner have on the process? What about the voltage/current applied? My old battery charger barely registers any current draw, yet there's been a steady stream of bubbles coming off of these brackets for many hours now and clean metal is magically emerging from the filth. Whilst that is going on, I'm reading up on the ins-and-outs of the plating process......

How did this work out pease. I’m planning to plate the same brackets.
I usually coat newly plated components in Waxoyl before refitting. Not sure it is necessary but must increase the durability of the repair.

 

[TFG]

@philward - I finally got everything set up on the plating kit and finished prep'ing the brackets. It looks as though I had the current set just a bit too high (witness the dark tinges on the extremities of one bit & the pitting where the hanging wire was attached, bottom right of picture) but for my first proper attempt at plating something useful, I'm reasonably pleased with it. It looks better in the photo than in the flesh, as it were.

It appears the secret is all in the prep. I should have spent longer getting the pitting out before plating. Reading a few articles on't'interweb, it sounds as though the 'trade' away to address this is by a generous dose of copper plate to start off with, then polish that back to get a good surface before moving on to the zinc or nickel etc.

The second one is in the tank as I type this. I'd better get back to it....

 

[Little Dog]

@philward - I finally got everything set up on the plating kit and finished prep'ing the brackets. It looks as though I had the current set just a bit too high (witness the dark tinges on the extremities of one bit & the pitting where the hanging wire was attached, bottom right of picture) but for my first proper attempt at plating something useful, I'm reasonably pleased with it. It looks better in the photo than in the flesh, as it were.

View attachment 44546

It appears the secret is all in the prep. I should have spent longer getting the pitting out before plating. Reading a few articles on't'interweb, it sounds as though the 'trade' away to address this is by a generous dose of copper plate to start off with, then polish that back to get a good surface before moving on to the zinc or nickel etc.

The second one is in the tank as I type this. I'd better get back to it....

Looks good except for the burning, I get that occasionally and think it has something to do with current being too high particularly around where the suspending wires contact. I've had problems with yellow passivate though; has yours stuck to the zinc?

 

[TFG]

Looks good except for the burning, I get that occasionally and think it has something to do with current being too high particularly around where the suspending wires contact. I've had problems with yellow passivate though; has yours stuck to the zinc?

Re: burning - Yes, I thought that it would appear close to the hanging wire, but the bracket was suspended in the plating tank with a wire around the small tang at bottom right of photo (i.e. not the wire you can see at the top), so the burning was just about as far away from the wire as it could be. Burning is a sign of over-current, as you say. I can't have over-done it by much. I need to do some more reading up about the problem. Working out the surface area for a part like that bracket is tricky and without it, it's difficult to set the current correctly.

Yellow passivate - yes, the same problem as you, with it not taking. I waved it around in the passivate for a good 90 seconds, but the slightest touch on it immediately after seemed to take it off. There are a couple of new vids on YouTube by Gateros customers that are worth watching. They are far more instructive than the ones that Gateros themselves have produced. One of them suggests dipping the plated item back in the pickling salts for a few seconds (until it starts fizzing) before rinsing and then putting into the passivate. Presumably this etches the surface of the plating to give the passivate more of a key?

I've also been reading the Gateros blurb on electrolytic cleaning, as championed by your good self. The paragraphs about anodic & cathodic approach are interesting and also the mention of switching between the two on a timed cycle. As ever, what starts out as nothing more than a dirty bucket, a lump of iron and a battery charger turns out to involve more than meets the eye. I wonder whether it might help with getting a decent surface to the part, prior to plating.

I also see that they sell copper plating kits. I might give that a go. I need to find a better way of prep'ing parts for (nickel/zinc) plating.

 

[Little Dog]

Apparently the yellow does not stick to the brightener. There are several ways of getting rid of the bright coat:
Don’t put it in, then black passivate in particular looks very dull. Still working it out.
Etch the part before passivate, only gives medium success.
Dip in clear passivate before yellow, some success with small parts.
Rinse part in fresh water for minutes before passivate, not tied this yet but base on my successes being on small parts this could be the key.
Mechanical removal, cleaned loose yellow off with a brillo pad rinsed it and dumped it back in. 24 hours after plating; yellow stuck.
Not tried with yellow for a while but will again soon.
Had some parts burn at the bottom, or at some other extremity, a point where a stream of bubbles can be seen rising from. The rest of the item is fine and identical items are fine. There is something left after prep that causes higher conductivity at theses points.
Had a part plate fine but damaged the plate in my press. Plated it a second time and it came out looking like a zebra. Got lots to learn.

 

[Little Dog]

I've also been reading the Gateros blurb on electrolytic cleaning, as championed by your good self. The paragraphs about anodic & cathodic approach are interesting and also the mention of switching between the two on a timed cycle. As ever, what starts out as nothing more than a dirty bucket, a lump of iron and a battery charger turns out to involve more than meets the eye. I wonder whether it might help with getting a decent surface to the part, prior to plating.

Don’t swap the +ve red and -ve black. The iron connected +ve is sacrificial, it turns to brown slime. Connect your component to the positive and you will reduce it to brown slime.

 

[TFG]

Don’t swap the +ve red and -ve black. The iron connected +ve is sacrificial, it turns to brown slime. Connect your component to the positive and you will reduce it to brown slime.

What Gateros are saying in their notes is that making the part the sacrificial anode can be used to erode the surface and with it, the imperfections (hopefully). Slime aside, I'd be interested to try this on a test piece just to see what happens. At some point, one needs to remove material from a pitted part to get a good surface back. Doing it mechanically is tedious and often difficult, especially on internal corners and details where access is compromised. The alternative is to copper plate to fill the pits and then polish the copper back to a surface. That still doesn't mitigate the access problems one's got to get the copper to plate into those corners in the first place.

 

[Little Dog]

Don't over cook it; that was a brake master cylinder

 

[Gus]

Amazed to read this molasses trick.
I just happen to work in an animal feed mill, we take in a tanker full of molasses every second day. Time to dig out some old motorbike parts and try this out, cheers pal.