not sure if I am talking about the same thing, but I use Evaporust quite a bit. Its very slow to work but excellent for removing rust from all items. an advantage is that one can immerse painted or chromed items without harming un-rusted parts.
I have a bucket with lid and I simply chuck rusty parts into it and leave for days or weeks until I need them. The rusty sections often come out black and need to be cleaned, scrubbed or buffed. I've found it great in petrol tanks and normally leave it in for several days.
Its advantage is that it is a benign substance (except to rust) and disadvantage is that it is slow acting. I'd leave it in the tank for a few days or weeks, empty it out and do your best to clean out the tank with detergent.
One good idea is to throw some old bolts and nuts into the tank with a little water and detergent, seal the tank and wrap in an old blanket, then stuff it into the clothes drier (when she-who-must-be-obeyed is not home). make sure all the extra spaces in the drier are filled with old towels etc, then put on gentle cycle for about 20-40 minutes. Results will be very peasing as long as the tank stays sealed and water does not leak out.
After running through the drier, clean it and obliterate all evidence of your activities before she comes home!
I might be obtaining a 'relic' part for a Vickers machine gun tripod and was wondering about the best ways to clean it up and preserve it.
I've been listening to other guys who have de-rusted parts in a bath of Molasses with amazing effects. There is quite a bit about it on the internet if anyone cares to look.
It's a slow process but its safe to yourself and the environment and ordinary steel parts. It's also relatively cheap.
I might give it a go!
Here is one chaps findings. https://www.youtube.com/watch?v=vq5IUiYMhRM
Ron
email (option): ronpier@talk21.com
Has anyone tried the molases method ?
Friends of mine into collecting jerry cans submerge them in a dustbin half full of farm molases ( the stuff you buy to feed to cows! £1/litre) diluted 10:1
Seems to remove the rust and leave original paint and markings in place.
Take a look
https://www.youtube.com/watch?v=vq5IUiYMhRM
Rich
email (option): richardpurkiss@hotmail.com
Hmmmm
Just back for hospital and straight into shed - yes it is (very?) slow acting, and no it doesnt seem to attack anything .......
I also chucked a voltage reg unit frame (the bottom, tin bit) into some - as a third test - some blackening, but no evidence of actual clean metal?
As i say, the effect is very like Citric acid - in fact slower acting.
A gallon of citric acid was prepared for ~£2.50 (using brewers citric - cheaper, MUST be available) .... so unless something happens to change my mind, this option seems to be a cheaper method of similar effect.
The Brick-cleaner (16% HCl)was faster acting - but as with any acid, i would'nt turn my back on it for long!
I did try it on the cams heavily pitted cams, currently in the 3HW - it produced a very black 'satin' effect, which could be removed with a wire brush - very like some heat treatment process's.
Never tried the molassess trick, not sure why it would work? though it did stain/attack the 316L SS components used in the m/c's we supplied to BritSugar @ Newark - pity i'm not working there any more - must find a local supplier.
I am surrounded by farms - unfortuntely due to milk price, they seem to have given up with cows ........
I have been down the mollasses/black treacle route and it works.
It works faster in the warm, which is why the aussies like it, just leave it in the sun.
It seems to leave a peculiar rough surface on some things I put in it, it needs to be cleaned off and painted ASAP.
It will not harm paint though.
It needs about 3 weeks here, more time in the winter,the worst bit is when you are grabbing the small stuff in the bottom of the bin and realise the squidgy bits are pickled mice..... they love to commit suicide in it.
Interesting cultures grow on the surface, diy penicillin
Personally I think its not really worth it and am looking into the electrolysis method.
Just come in from shed (so much for being incapacitatied after 'op') - and am even less impressed.
Nothing to report on the Regulator-base, f***-**l progress on fuel tank, and the tank heater's been on @ 40deg all day and as for the slightly corrosion-etched cam - nothing.
Life's too short to wait weeks to get rid of a bit of external rust!
As for what inside the fuel tank - my instinct is to find phorphoric(?) acid, which is the base for Naval-Jelly/JENOLITE (i want a liquid product) or, as you say go down the electrolysis route.
phosphoric acid on ebay, by the pint
Need to sort my spell check - never thought of Ebay for chemicals .......
Just back from shed, have officially given up on the stuff, when i can lift weights, it going down the drain - not impressed!
I'm not even trying to remove big flaky stuff, just that annoying 'etched' rust that you have to remove too much, otherwise good metal, to get at.
Did'nt bother me in the past - all my other bikes are very original - oily-rag restorations - I blame this bloody forum for making me so particular with my anglo-indian mongrel!
found some - APC (Manchester) - 2.5l of 85% Phosphoric acid for ~£14 a much better deal.
Intrestingly, thay also do 'virgin' methanol for about £1.40 litre if bought in bulk .......... hmmm
The B25 could on dope next year.
Hee, hee, heee ......... been playing with my Phos. Acid.
@ 85% concentrate, its syrupy.
Tried full strength on a couple of steel brackets, burned in last yeasr bonfire and nicely rusty.
Even @ 14degC - immediate effect, with lots of smelly gases and foaming.
Decided to dilute 50:50 by volume - working well, so left them for 4 hours.
One side bright metal, the other less clean due to some red deposits (ash ?) - scraped these off and diluted the mix again 50:50 by vol, as i wanted to immerse an 'etched' Norton crank-pin.
Left it another 1 hour and washed and very lightly scrubbed with a plastic bristle brush - both sides bright metal, with the odd bit protected by paint or something.
Very impressive.
None of the black cletated ferrous oxides needing removal with a wire brush, just bright metal.
Will try with ali, zinc plate, chrome and some cast iron to see what happens, but so far everything that Vapo-rust is not!
For gods sake wear eye protection with this stuff, its a bit hard on the hands, but a bit of washing up (to keep swmbo happy) stops them stinging!
probably not a good idea for any aluminium alloyed article..............
unless you no longer want it of course
I dropped a couple of slightly rusty bolts into dilute phosphoric acid once, just to clean them up a bit. Then forgot them and instead of the hour or so I had planned on it was a couple of month later that I wondered what the scummy mess was in that jar on the shelf. Rust was gone but also a lot of metal and all the threads. 
Cheers
Pete
OK, some facts;
In the above (85% w.w. conc) of Phos. Acid - diluted 4:1 by volume with (hard) tap water @ 17degC.
ALUMINIUM - HT30 (or simlar) - after 4 hours immersion - losses its shine, has a grey easily removed skin which when removed shows minimal material loss but a matt 'etched' surface.
This is expected as most 'pure' Ali's are suprisly corrosion resistant - the corrosion problems start when you start alloying it - DURAL is a very good example.
MAZAC - a generic zinc alloy bearing housing from some electrical tool or other - weeeeeee, very reactive!
after approx 20mins nice and shiny?
after 1 hour, covered in a dark grey skin (easily removed) with signs of serious errosion.
I would suspect 24 hours would reduce it to sludge.
NORTON CRANKPIN - +24hrs
Intresting - the bearing tract and side 'cheeks' turned black, with a rough etched feeling?
The parts of the shaft which press into the crank-webs - virtually untouched, with some darkening of the corroded spidering.
The (ground?) threads - basiaclly untouched.
A strange result - perhaps due to a localised hardening process ?
BDMS - a 1/2" sq test bit of shiney steel - after ~4 hours no effect whatsoever.
Left in for ? hours to see what happens.
Rusty steel bolts (5/16" Cycle) - after ~4 hours turned black, left in for ? hours to see what happens.
Zinc Plate - after approx 1 hour, turned dark grey, then black.
BRASS - i did expect this to be effected, as the acid went for the zinc.
Not so, it seems after 12 hours to be uneffected, i am leaving in the acid as i expect something to eventually happen.
Seems as if the Phos. Acid preferentially attacks iron oxides but is not the 'beast' its made out to be.
Yes if you leave metal in most acids it eventually gets eaten - but alkylies are far worse on Ali. than this stuff.
It does seem to go for zinc though!
I'll wind this up for now as i'm bored, if anthing 'exciting' happens i will report - it does seem to be a cheap method of neutralising rust in a petrol tank - i wiull try on my next tank to sort.
The molasses and water mixture works very well and is cheap,last's for ages. I store mine in a 40L plastic drum with a screw type lid and outside. You may have to leave parts for a few weeks so not a fast process.
Something i will try, eventually.
Fascinated what the active ingrediant is, in the Molasses.
in a previous life i did a LOT of work with Britsh Sugar - extracting sugar from sugar beet (as opposed to cane) - a very sophisticated process, with incrediable recycling of energy and materials - resulting in the 'waste' product of MOLASSES.
Not really a waste as its added to pure (white) sugar to produce healthier (????) Brown sugar and to the boiled out beet fibre - as an animal feed.
The point of the above is that nowhere in the process is there any evidence that molasses or the origin of the molasses is anything other than a very benign chemical ?
No 'special' materials are used in the process - standard 316SS and in the case of the Centrifuges - low carbon structural steels (cannot remember the BS. numbers).
Bearing in mind that it is a very high temp process, i would have thought whatever the active chemicals are in the Sugars/Molassess mix - would have had a cleaning/derusting effect on the steels used.
Anyhow, my ramblings - people say it works and just need to get around to trying it.