DarrenW
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| posted on 5/8/09 at 05:10 PM |
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Rust removal
its been years since ive had to remove rust. Loads of ways, loads of old wives tales - however what is the best proven method?
Some small parts may do with electrolsysis, however what about big parts (like mini shells and subframes)?
Shot blasting and acid dip is out iof the questions as the parts arent that bad. Is it right that if i remove the rough bits with the angry tool, the
paint with good quality stuff - as long as air doesnt hit the metal it wont rust any more? Or does the rust need to be converted first.
Is POR15 the best paint for unseen parts? Or is hammerite still recommended? Ive used chassis enamel before but it seemed to rust again after a couple
of years use.
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StevieB
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| posted on 5/8/09 at 05:17 PM |
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If you're not in a major rush and are of strong constitution, soaking in malt vinegar works really well.
I did some of my donor parts - soaked for about a week and gave them a cleaning with an old toothbrush occassionally. Once finished I washed
thoroughly in clean water and then stuck the parts in my gas BBQ to draw al of the water out of the porous castings then a quick going over with a
wire brush to finish.
Worked a treat and despite not treating or painting some parts, theylve still not rusted very much at all more than 2 years on.
Bloody stinks though, and to do a subframe you'd need a bloody big tank and plenty of vinegar (it's very cheap though!). I guess a
plywood box lined with pond liner would do the trick nicely, with a lid held down by brick as far away from the house as possible and down wind!
ETA
For the body shell you could always get one of the light duty sand blasters like the ones bodyshops use. My mate used to work at a BMW bodyshop and
that's what they used to sort out rusty stone chips and the like - very light pressure (well, enough to hurt without breaking the skin on your
arms IIRC  )
[Edited on 5/8/09 by StevieB]
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omega0684
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| posted on 5/8/09 at 05:25 PM |
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home made electrolysis bin! no need to wait for a week, just leave it running over night
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DarrenW
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| posted on 5/8/09 at 06:23 PM |
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Ive not done electrolysis before, may need to dabble. With any luck Coozer will have some kit i can try.
Ill probs use wire wheel in angry grinder under the body to get the floor clean before painting.
I wonder if my kit car build trestles will be man enough to hold a mini up
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Confused but excited.
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| posted on 5/8/09 at 06:38 PM |
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Oxalic acid gel works fairly well.
I bought some from R&D Laboratories (Google Mistral Cleaning). They post, no problem.
Tell them about the bent treacle edges!
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DarrenW
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| posted on 5/8/09 at 06:42 PM |
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oxalic acid is the active indgredient in products to remove tanin stains in oak worktops.
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mookaloid
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| posted on 5/8/09 at 08:35 PM |
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quote:
Originally posted by DarrenW
oxalic acid is the active indgredient in products to remove tanin stains in oak worktops.
and how would you be knowing that then? 
"That thing you're thinking - it wont be that."
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DarrenW
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| posted on 5/8/09 at 08:43 PM |
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quote:
Originally posted by mookaloid
quote:
Originally posted by DarrenW
oxalic acid is the active indgredient in products to remove tanin stains in oak worktops.
and how would you be knowing that then?
Mmmmmm, i wonder.
For the benefit of others - dont ever leave anything steel based on an oak worktop overnight - no matter how wel they have been oiled. There is a big
risk of the steel reacting with tannins in the oak and leaving a very difficult to remove black stain.
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matt_gsxr
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| posted on 5/8/09 at 10:21 PM |
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Oxalic acid is the toxic component in rhubarb leaves.
Presumably to meet the £250 budget you could derust with crushed rhubarb leaves!
Matt
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Gunner1
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| posted on 6/8/09 at 04:24 AM |
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Something that has worked very well for me, including derusting brake drums to where they look like new, is to mix a solution of one part of molasses
to ten parts of water. Leave the parts in for a week or so, and hose/scrub off the rust. The solution is cheap and if you need to do big parts, dig a
hole and drop in some six ml poly to make your tank.
It truly is amazing and no problem getting rid of the stuff afterwards. Just chuck it on the lawn. I have kept mine going for three months, although
it was pretty rank by then. The solution will not dissolve paint or grease, so you gotta take that off first.
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StevieB
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| posted on 6/8/09 at 06:39 AM |
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quote:
Originally posted by Gunner1
Something that has worked very well for me, including derusting brake drums to where they look like new, is to mix a solution of one part of molasses
to ten parts of water. Leave the parts in for a week or so, and hose/scrub off the rust. The solution is cheap and if you need to do big parts, dig a
hole and drop in some six ml poly to make your tank.
It truly is amazing and no problem getting rid of the stuff afterwards. Just chuck it on the lawn. I have kept mine going for three months, although
it was pretty rank by then. The solution will not dissolve paint or grease, so you gotta take that off first.
I'm tempted to give molases a go next time - got to smell a lot better than vinegar!
In truth though, I'll probably just send parts away for shot/vapour blasting and save all my time for the nice puttin clean stuff back together
jobs...
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DarrenW
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| posted on 14/8/09 at 10:25 PM |
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Some good ideas so far.
Molasses - i need to ask - what is it?
Lets assume i pull the rear subframe out of the mini. This reveales the boot floor that was replaced 2 years ago so in fairly good nick. I want to
wire brush and paint. What would you use to derust some areas? (stuff that can be left on and wont need to be washed off).
What would you use to paint it? I was thinking several coats of black hammerite / smoothrite followed by stone chip or underbody schutz before
refitting the subframe. How does that sound?
I seem to recall the trick is preventing oxygen and dampness getting to any bare or already rusted steel. Does the rusted surface have to have rust
converter applied first?
Ive used cheapo chassis black paint before but didnt seem to do a good job. Dont want to use POR15 as ive heard you have to be careful to apply
exactly right or it wont work, and i dont have the budget for it.
(BTW - the shell is quite solid so localised rust looks like surface corrosion only).
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DarrenW
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| posted on 15/8/09 at 09:57 PM |
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Went to local bodyshop today. Bought some zinc rich red oxide primer and chassis black paint. Hopefully a few coats of each will hold further surface
rust back.
Got covered in red dust using the tool. I hate those things - was picking steel shrapnel out of legs for ages
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David Jenkins
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| posted on 16/8/09 at 09:55 AM |
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quote:
Originally posted by DarrenW
Got covered in red dust using the tool. I hate those things - was picking steel shrapnel out of legs for ages
I usually wear my leather welding apron - got fed up with little red puncture wounds all over my legs! 
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rusty nuts
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| posted on 16/8/09 at 01:07 PM |
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quote:
Originally posted by David Jenkins
quote:
Originally posted by DarrenW
Got covered in red dust using the tool. I hate those things - was picking steel shrapnel out of legs for ages
I usually wear my leather welding apron - got fed up with little red puncture wounds all over my legs!
I normally end up with the wounds slightly higher !
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David Jenkins
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| posted on 16/8/09 at 01:15 PM |
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Short-arse!
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