rust work, not sure what to do really.

[droopsnoot]

It'll be interesting to hear your thoughts on it, see if I'm just imagining how similar it is.

[MiataMark]

plus 1 for citric acid I was amazed at how well it worked on some brake caliper carriers, also for smaller items electrolysis.

I've always used kurust for treating parts before painting.

[slater]

I wouldn't be suprised if deox-c is just citric acid..

There's quite a few acids you can use. Acetic (vinegar), Citric, oxylaic (molasses contains this) even dilute hydrochloric. It's imperative it's cleaned and nutralised properly afterwards tho. If the acid gets into seams or holes and doesnt Get washed off your parts will rust again in no time.

[droopsnoot]

Sept 25, 2018 9:33:27 GMT MiataMark said:

also for smaller items electrolysis.

Interesting, I tend to use electrolysis for larger items, rather than smaller ones - ones where I am too tight to buy enough acid to soak them, usually.

Sept 25, 2018 11:23:41 GMT slater said:

I wouldn't be suprised if deox-c is just citric acid..

I have wondered if that's what the "C" means in the product name.

[MiataMark]

Sept 25, 2018 18:07:36 GMT droopsnoot said:

Sept 25, 2018 9:33:27 GMT MiataMark said:

also for smaller items electrolysis.

Interesting, I tend to use electrolysis for larger items, rather than smaller ones - ones where I am too tight to buy enough acid to soak them, usually.

I used citric acid for some discs and electrolysis for others, calipers were put in citric, I think I used electrolysis on the calipers. Have a picture of a vented disc in citric acid...

[hohocc]

I recently had some radiator hoses that were in reasonable condition, but were full of rusty flakes/sludge which were stuck to the inside and could not be scraped off. Rather than chuck them I had a go at dunking in citric acid (2 tablespoon/litre roughly) and over a week or so most of the muck was softened enough that running a water blaster through them cleaned everything up really well. Didn't appear to have any effect on the rubber hoses which surprised me.
Citric acid is great stuff.

[chris y]

I've used electrolysis on very heavy rust on brake calipers, very effective but leaves a black surface.
I painted them with silver basecoat and 2k clear laquer and a couple of years later they are still the same so it didnt cause a big problem.

My point is though that Deox cleans things back to the point of shiny sparkling steel, better than electrolysis. What surface does the citrix acid leave?

Another plus for Deox is that it doesnt touch chrome so you can put pitted chrome items in and clean the rust out of the pits to stop it developing further without ruining the chrome, I'd be very wary of putting chrome in any acid, has anyone tried it?
What I did with chromed parts (I built a few old raleigh bicycles, so things like wheel rims) was deox them, then wipe them over with silver paint so that it filled the pits, but wiped off to leave clean chrome. It worked very well indeed.
Chrome parts that arent too far gone but cost lots to rechrome can be made to look vastly better cheaply this way.

[MiataMark]

Sept 26, 2018 20:52:56 GMT chris y said:

My point is though that Deox cleans things back to the point of shiny sparkling steel, better than electrolysis. What surface does the citrix acid leave?

Back to clean metal, if I remember correctly.

[slater]

The surface will be etched as if it had been sandblasted. If the rust was bad you will see pitting too. You get this with deox-c too tho.

[droopsnoot]

Sept 26, 2018 20:52:56 GMT chris y said:

I'd be very wary of putting chrome in any acid, has anyone tried it?

I haven't tried chrome parts, but I was just about to post that if you put some plated parts in citric acid, it will remove the plating. I just did a batch of brake unions that I bought which have some surface rust on them - they were yellow-passivated (or cadmium, or some other yellowy bright finish) and after the citric acid, they are clean steel. I still have the jug of citric on the go, I'll dig out a chrome thing and stick it in later and report back on the results.

The finish I get out of citric is just plain, clean metal. It gets brighter after a quick go with a soft brass wire brush. Here's a bit of Audi coupe rear light frame, before:




As you see, some rust where the panel behind has been spot-welded up to it.

Here's the same section after it's been in citric acid for about 24 hours, though I did remove it and poke at a couple of thicker bits of rust half-way through - a stronger solution might stop me having to do that:



All the rust has gone, and it's back to clean metal. Once I remove it from the acid, I run it under some plain water to wash the acid off (from a water butt, so it's rain water) and then dry it with a hot air gun to stop flash surface rust, then brush with brass wire brush. It's a bit pitted, but that's where the rust has eaten into the steel. In this case it's not badly pitted and can be re-used.

ETA - all except one of those holes is a spot weld that I've removed out. They *really* don't want the rear light frame coming away from the back panel.

[bmw2101]

thats interesting so or example, ive 2 chrome bumpers for my mini, if i put them in citrus, the chrome will disolve, and then i can paint them nimbus grey for my car?


Thread is really interesting now. will get some citrus.

[slater]

The zinc passivate plating will strip in most acids in next to no time. Zinc is very reactive hence why it is used to plate items. The zinc dissolves so the steel does not.

Chrome is the oppesite principle it's less reactive and is used to encase the steel and stop water getting to it. You will notice with old chrome how the steel rusts out underneath and the chrome plate stays intact and just breaks up.

I think to strip chrome you want an electrolysis process. Simply immersing in acid will do next to nothing and would dissolve the steel quicker than the chrome. (Take alot of acid to dissolve an entire bumper tho!) Hydrocloric will dissolve chrome but i think it would be a very slow process if cold. Citric acid or similar may not touch it at all so it's worth an experiment. Remember the chrome is plated on copper first too. Hcl shouldn't touch this if it's clean but if there is a copper oxide present then this can dissolve and once copper is in solution (acid starts to go blue) then it is capable of dissolving more copper slowly. In citric acid I'm not sure if this is even possible but I'm pretty sure it's at least very unlikely.

[droopsnoot]

I've put a small chromed badge into some citric yesterday, but I don't have any "after" photos. Basically it seems to back up what slater says above - it doesn't seem to be touching the chrome, but I will check again later on. Certainly it's correct that the passivate goes in no time - really gets the citric fizzing.

I think the chap I use for chroming said he was using Hydrochloric acid to strip chrome, but I know there's more than one chemical involved in the process. One item I took to him went through the first acid, then completely disintegrated in the second bath. Fortunately it wasn't a rare item.

To remove chrome from a bumper, especially one that has a relatively simple shape, I think I'd use a mechanical process with a couple of flap discs in an angle grinder. A bit noisy, but much less messy. You'd need a big bath and a lot of acid to stick a bumper in. As you're painting it afterwards, some minor surface issues don't matter because you can use high-build primer and/or stopper prior to paint.

[jonsey]

The guys on the Raleigh Burner pages on FB soak their chrome in Citrix acid to clean the rust. Take a look. They all swear by it.

[droopsnoot]

I've had a look at my chrome piece today, and where the chrome is good it's still in tact after 24 hours in citric acid. The bits where there is plain metal are now clean, similar to the panel I posted above. There's some staining on the outside of the piece, but I can't swear that wasn't there before as I didn't clean it up before I soaked it.