Citric acid and rust

[dutchzcarguy]

8 hours ago, Captain Obvious said:

 
   
   

top tip: Now if you have to plate long springs  I put an elongated piece of steel with notches in the ends IN the spring so that it is stretched and the spring becomes perfectly plated.. 👍

Your parts look very nice CO!

 

Edited November 27, 2020 by dutchzcarguy

[Captain Obvious]

2 hours ago, dutchzcarguy said:

if you have to plate long springs  I put an elongated piece of steel with notches in the ends IN the spring

That's a neat idea. Too late for me, but neat anyway.

The longest springs I had were the return springs for the round top carbs. Next longest was the return springs for the throttle body. Oh well... Maybe next time.

[Captain Obvious]

9 hours ago, AK260 said:

I geeked out on my box of shiny bits ...

Absolutely! I was geeking out last night, and I plan to do more today. About half the very small parts are hardware bits and pieces for carburetors. The trouble is figuring out what goes with what. As I tossed stuff into a box at the beginning of this project, it was "No problem, I'll remember what this went to". Well now that I'm looking at a vast pile of tiny yellow parts that I took apart starting maybe two months ago? Not so easy...   LOL.

I tried to wire the small parts together in a configuration that would make them easy to identify and sort into appropriate applications, but even that plan seems to have gone all muddy and indistinct. By the end of the pre-processing, I knew I was running out of time and I stopped being so contentious about what went with what. I just needed to get stuff done and off to the platers.

The big stuff like the inspection lamp and coil bracket, etc. That stuff is easy. It's the little nuts and bolts that are the hard part. And it's a mix of round top and flat top carb parts.

Anyway, a nice hot cup of tea or two and a comfy stool at the workbench and I'm good to go for the afternoon. That's my plan.  

[Captain Obvious]

15 hours ago, grannyknot said:

Something you mentioned earlier about the rust just falling off, yes most of the rust accumulates at the bottom of the bucket, I think that might be part of the reason why the solution keeps working for so long.  I've had a bucket of solution working for up to 6 wks with it cleaning dozens of parts before it 's used up.

I found the solution slowed down removing the original yellow chromate and zinc as it was used. Maybe the rust removing properties stayed about the same, but the original foaming as the yellow disappeared and (what I believe was) the zinc got eaten off slowed down as the solution was used. For that reason, I changed out the solution often and that's why I went through 30 pounds of it.

If you haven't tried it yet, put something that still has some of the original plating and chromate on it into the bath and see what happens. It comes out beautiful, but unplated. If you pull it before it's completely done, you can even see the layers being eaten off. Kinda like sanding through multiple layers of paint where the different layers feather out as you sand to the metal at the bottom. Yellow layer, and thin metal layer beneath that which I can only imagine is the original zinc plate.

I haven't disposed of the used solution yet either. I didn't just dump it down the drain. If it was just rust and iron, I wouldn't be worried at all and I would just dump it. But that yellow coating (involves chrome?) and the zinc have me a little concerned. I'm going to call the guys at my local water company and see what they think. They may tell me it's no problem, just pour it down the drain, or they may tell me to hold it for one of the local hazardous waste drop-offs we have occasionally.

[AK260]

Absolutely! I was geeking out last night, and I plan to do more today. About half the very small parts are hardware bits and pieces for carburetors. The trouble is figuring out what goes with what. As I tossed stuff into a box at the beginning of this project, it was "No problem, I'll remember what this went to". Well now that I'm looking at a vast pile of tiny yellow parts that I took apart starting maybe two months ago? Not so easy...   .
I tried to wire the small parts together in a configuration that would make them easy to identify and sort into appropriate applications, but even that plan seems to have gone all muddy and indistinct. By the end of the pre-processing, I knew I was running out of time and I stopped being so contentious about what went with what. I just needed to get stuff done and off to the platers.
The big stuff like the inspection lamp and coil bracket, etc. That stuff is easy. It's the little nuts and bolts that are the hard part. And it's a mix of round top and flat top carb parts.
Anyway, a nice hot cup of tea or two and a comfy stool at the workbench and I'm good to go for the afternoon. That's my plan.  

I hear you completely! I did this to start with so as to be able to identify all the bits afterwards ....



... but even then I kept not being able to identify other bits I had chucked in at the last minute!

At least it’s a fun jigsaw puzzle with a beer in hand!

[240260280]

I ran all my extra nuts and bolts through a vibratory tumbler then oiled and packed in baggies for a later date.

Next time I may hook up a recirculating pump with a filter and run evaporust through the tumbler system.

https://youtu.be/RRBi1lC873I?t=127

https://www.youtube.com/watch?v=cl1fB-eYt7U

 

Or clean while you drive:

https://www.youtube.com/watch?v=Hr5PNQeZRi0

 

[240260280]

 

[240260280]

Big job:

https://www.youtube.com/watch?v=tRnHMJZQtKc

 

[Captain Obvious]

Thanks for the input @240260280. It seems that hydrochloric acid is clearly the most effective. Comes with all the safety downsides, but definitely the most effective.

My plater said that everything was going to go through a quick hydrochloric dip before the plating solutions. My thought was to get as much off as I could beforehand and hopefully his quick hydrochloric dip would take care of the rest. I was thinking that his hydrochloric dip would take off any surface rust that developed while the parts sat in boxes waiting until I had everything prepped and ready to go.

[Patcon]

I also did some parts in citric acid and they turned black or had black clouding on them. It comes off on your hands. After they had been dipped, I bead blasted them again and they looked fine

[Captain Obvious]

From my limited experience, I think that is leftover zinc from the original plating.

I didn't look into it any from a chemistry standpoint, but when I was doing the citric acid cleaning, it seemed like the yellow chromate came off quickly (if there actually was any remaining), and then the zinc came off next at about the same rate at which light rust came off.

So I'm thinking that if you would put those parts back into a citric acid bath again (maybe a fresh (warm-to-hot?) bath), I think those large darker patches might come off and leave you with a homogeneous surface.

[Patcon]

I might experiment some...