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 vlad01
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| posted on January 11th, 2013 at 12:55 PM |
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| Quote: | Originally
posted by viiking
Don't disagree re the molasses, but for most of us city sllickers molasses would be difficult to obtain in bulk.
So what I have done is to get a large tank called an IBC or Intermediate bulk container. These are the square plastic containers of 1000 litres with a
steel cage around it. I get mine from work, but you sometimes see them on ebay. Cut off the top plastic so you can get the parts iin. Put in the water
and then citric acid. For a half full tank you put in 500 litres of water, and 25kg bag of citric acid. Actual concentration is not critical. As I
work in the chemical industry I can get the citric in bulk cheap.
I have treated my doors, mudguards, boot and bonnet and donor complete quarter panels this way. Whatever you can fit. Small parts can go in drums,
buckets or whatever else you have lying around. The solution does NOT go off but continues to work for a long time -has no smell, doesn't burn - you
can put your hands in it no problems UNLESS you have cuts in which case you get stinging.
Alternatively you can build a frame out of wood, or bricks or even just mound dirt and place in a tarpaulin big enough to hold the item in question
inside and then fill with water. Wouldn't suggest going too high, maybe 100-200 mm might be enough depending on what you are trying to immerse.
Re the HCl. I agree concentrated stuff is nasty. But when you dilute it from the 32% solution you buy say from Bunnings, 10-fold, it is not much of a
problem.
So Citric Acid has the following benefits:
1. Reasonably cheap.
2. Doesn't smell awful like molasses or vinegar or pool acid
3. Works quickly depending on how strong you use it.
4. Is relatively innoccuous - won't burn the bejesus out of you. It is used in soft drinks and lollies so it can't be too bad for you
5, It is not difficult to get rid of when you have used it.
Do some google searching for it or watch this video. It really is the best method I have come up with.
In all cases it is best if you can remove as much of the offending crap as possible like oils and greases as this tends to create big grease balls in
the solution.
http://www.youtube.com/watch?v=ckdMdiJlV7c
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molasses is bought from pet/animal food supply shops. Alternatively from a horse shop.
I like your idea on the 1000l water tanks.
might try that one.
where do you buy citric acid from? can you get bulk sodium hydroxide? and is that expensive?
sodium hydroxide is one of the key chemicals I use to complete the process for un-rusting bare metal.
71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE |
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Dubsky
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| posted on January 11th, 2013 at 06:45 PM |
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From what I understand citric acid and molasses both work using the chelation process. The solution breaks the bond between the rust and the iron
without attacking the iron as with some acids.... I bought 25litres of molasses ($40) at the local stock feed shop here in Canberra, that should make
250 to 500 litres depending on who's mix you go with. I'm happy to wait a while for it to work as I have plenty of other jobs to do on the car.
Viiking, How long does it take to remove heavy rust in your solution of 500 litres of water to 25kg of acid? And where can I get a 25 bag in
Canberra?? 
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viiking
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| posted on January 11th, 2013 at 09:41 PM |
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Try googling chemical suppliers. As previously discussed try places that sell home brew supplies for citric acid.
Any base will work to neutralise. Caustic soda (NaOH) is also very concentrated and nasty. You could try bicarbonate of soda or even "pH up" from
pool stores or even Bunnings. The alternative is to just keep flushing longer until all the acid has gone.
Heavy rust goes in days to a week. I will see if I can find some before and after photos of something small I did.
I would strongly recommend that you do a small scale test first with whatever quantity of Citric Acid that you can buy. If you get say 1 kg you should
be able to easily make 20 litres of quite strong solution. You can always scale up later if you are happy with the results. Do it in a couple of 10
litre batches.
Believe me it works!
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viiking
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| posted on January 15th, 2013 at 09:54 PM |
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Here's a picture of my engine tin which I have put in a 5% solution last night i.e. 24 hrs ago.
It is not overly rusty, but there are areas where there is surface rust. The piece is painted and the acid will take some time to soften and remove
the paint. I will help it along by washing it with a strong water stream and even a wire brush if I get impatient.
When I look closely at the piece I can see where it has removed some surface impurities already leaving a slightly (ever so slightly) pitted surface
where rust has been. This will be a perfect key for subsequent painting.
You can clearly see the "witness" or is that the "Plimsoll Mark" where it has not been fully immersed. I want to demonstrate a before and after
shot so you can see it.
The solution has turned from a lemon yellow colour to a clear reddish-brown solution due to the dissolved iron and paint residue.
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viiking
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| posted on January 15th, 2013 at 10:07 PM |
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Better picture of the tin. Note the pitting on the bottom right of the picture. This used to be surface rust 24hrs ago.
Sorry I am not so adept at getting the picture the right size but still staying within the limits imposed for files.
I think if you click on it, it will get bigger for you.
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 matberry
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| posted on January 15th, 2013 at 10:45 PM |
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Here's a pair of stock TP manifolds that have been in a molassis brew for a few weeks or more. Trying to unblock the carbon buil-up in the preheat
pipes......still soaking.
The alloy has a dark build-up of gunk that I was mentioning. It's odd that it is only in some spots.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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viiking
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| posted on January 16th, 2013 at 08:46 PM |
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I wouldn't think that molasses or my citric acid will remove carbon. It hasn't been created in an aqueous (water) environment but in an organic
(solvent) environment. The carbon is a problem because it is held together with a "varnish" meaning you need a solvent to remove it.
The correct chemical to remove carbon is probably butyl cellosolve or butoxyethanol. It is a carbon solvent. In the past it has been used to un-sieze
engines that have sat for a long time and cannot be turned over.
Google it. You may find it is the active ingredient in carburettor cleaners. Not sure if it is in Fuel Injection cleaner though. Get a can or bottle
and then spray the contents out into a can, or directly into the preheat pipes and leave it soaking for a while. Put a can or something under the
outlets in case it gives way, or plug off where you can. You should be able to use it again until it is fully contaminated. It also is a little
volatile and may evaporate so plug all pipes that it is in.
The chemical is somewhat toxic, so read the warnings and don't breathe it in for long. See can for warnings. For under $10 it might be worth a go.
I don't know how to spell KEMIST but I are one.
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matberry
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| posted on January 16th, 2013 at 09:37 PM |
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Thanks Viking, I'll try it.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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vlad01
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| posted on January 25th, 2013 at 07:54 PM |
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one bad thing about molasses is if you leave in for more than a year and it fills with leaves it stinks like thats putrid energy drink 
I emptied a whole bath tub. smelled exactly like that shit kids drink these days.  So yeah don't let too many leaves get in there,
71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE |
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Dubsky
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| posted on January 27th, 2013 at 05:36 PM |
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I'm impressed. I had a few parts in a tin , molasses @ 1:10 +sun, and after two weeks no rust but to my surprise it also stripped off all paint.
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