Article copied from the NSRA site. Credits to Tim Nicholls.
Article unmodified from the original.
I've been meaning to post about this for a while because everybody I've shown it to has either heard about the technique from somewhere but didn't believe it, or didn't know anything about it and was downright amazed. It'll remove the rust from any iron or steel item. I've saved a fortune by using this process to salvage parts that I thought were beyond hope and it's saved me hours of wire-brush and wire-wool time.
Hope this is useful to you guys.
Big thanks to my 12yr old son Josh for his services as photographer!
So, here we go with...
Dr Timo's Amazing One Hour Acid Rust Bath!
Step 1: Acquire some dangerous chemicals*
(*they're not actually all that dangerous at all)
What you need is Oxalic Acid Crystals. They're most commonly used diluted with water to bleach or remove stains from wooden floors. I get mine from http://www.agwoodcare.co.uk for about £41 for a 10Kg tub like this:
Step 2: Measure out the crystals & add some water
In this example I used 500g of crystals to make up about 45 litres of de-rusting solution. Plastic buckets make good containers for smaller components but as I was attempting to de-rust a cylinder head, I went for a nice big plastic packing crate:
Step 3: Stir up some trouble!
Keep your face out of the steam that comes off as you add the hot water.
This is really important.
It's not that the acid will eat your flesh or anything like that - it just irritates the skin and makes your throat sore. Use a long stick and stir the solution until all the crystals have dissolved:
Step 4: Dunk your junk
Gently lower your chosen rusty junk (erm...I mean your cherished hot rod components!) into the solution. Now is a good time to think about how you're going to retrieve them from the murky depths in about an hour! The solution won't have any effect on plastic so plastic washing line is good for smaller parts and nylon rope works for heavier bits. I used some old speaker cable for the heavy Pontiac cylinder head in the photo:
Step 5: Add more water
At this point, add just enough hot water to cover the parts you want to de-rust. No point in diluting the solution unnecessarily. Try to ensure that no air bubbles get trapped under or inside anything you're de-rusting. With regard to the ratio of crystals to water - I usually work it out so that the ratio goes no lower than 100g of Oxalic Acid crystals for every 10 litres of hot water.
Step 6: Don't fiddle with it!
As the acid gets to work on the parts it's important not to fiddle with it too much. The acid reacts with the Iron oxide and it ends up suspended in the solution as bright yellow particles. Eventually, these particles sink to form a yellow sludge at the bottom of the container. Even after a number of uses, the solution will still remain active but disturbing the sludge can leave a yellow greasy film on your parts (not nice!) so try to resist the temptation to poke your parts!
After about an hour, your solution will probably look something like this:
Step 6: Get your bits out
This is where you wish you'd read Step 4 properly and thought about how you were going to retrieve your stuff from the bottom of a container full of acid! Assuming you're smarter than I was when I first tried this, you'll be able to rescue your stuff no problem. Luckily - I'm smarter than I used to be:
Step 7: Bask in the glory of your new found chemistry skills!
A quick rinse with cold water will neutralise any remaining solution on the parts you just dipped. Now would be a good time to sit back with a cuppa/beer/fruit herbal infusion (your choice!) and admire your achievement (especially if you have an identical untreated part to compare it with):
Here's a bit more info about Oxalic Acid:
It has no effect on the base material. You could leave an item in the tank for months and it wouldn't corrode.
It has no effect on paint. This is really useful if you want to retain original paintwork on an item that has started to rust in places. The paint remains untouched.
It has no effect on chrome. Again, really useful for removing the rust ingrained in any pitting - it's surprising how much better an old chrime item can look after this treatment, even when the pitting remains.
You can legally dispose of old solution down a drain, as long as it's diluted well.
If you water rhubarb with diluted Oxalic Acid, it will become extemely toxic and can be fatal if eaten!
Chemical safety info about Oxalic Acid can be found here: http://ptcl.chem.ox.ac.uk/~hmc/hsci/chemicals/oxalic_acid.html
NOTE -- It won't work on oily parts though. Bits would need to be degreased first.
Also. HEALTH WARNING -- Do not EAT/DRINK/SWALLOW the chemicals as chances are you'll die.
__________________
Meep Meep.
'64 Bug - Almost ready to start Started  --> A flip from the norm !
Rods 'n' Sods - The UK's Best Rod and Custom Website
Aircooled Collective
Black Country Dub Club
|
