The Shop > Tools
De-Rusting - Experiments with Citric Acid.
Arbalist:
I'm with superc, I use a battery charger and washing soda. I've de rusted quite a few parts using this technique now.
NeoTech:
I've had success with citric acid + vinegar mixes. But after powerwashing and drying i have been blasting em with soda (more or less baking soda). to get that final grit out of there without disturbing the metal. So if you have a small blasting cabinet and dont need to run sand in it i can really recommend that method. Takes a bit more effort with the acid step but you kill off less metal which is good in my case (car restorations). =)
Pete W.:
Hi there, all,
Once again, thank you all for your contributions. :mmr:
--- Quote from: Arbalist on May 04, 2014, 05:56:59 AM ---I'm with superc, I use a battery charger and washing soda. I've de rusted quite a few parts using this technique now.
--- End quote ---
No way would I dispute the effectiveness of the electrolysis methods but I currently don't have anywhere I could set up the gear for it. I understand that with some choices of electrolyte the process emits a corrosive mist - I wouldn't risk that in my main workshop.
I wanted to experiment with the citric acid method to see how effective it can be and I started this thread specifically to record and share my results.
The phosphoric acid (aka 'Jenolite') process is OK for non-contact surfaces but it does leave a dimensional change that I wouldn't want on, for example, machine slides or running contact surfaces. I intend to use it on some rusty patches on the tin shed roof (see my thread, Pete W's Tin Shed Project') but I'm going to have to be careful where the rusty steel meets the still-galvanised surface.
Arbalist:
The problem with any type of acid is that it will eat away the parent material as well as the rust. With Electrolysis it does, I'm told, only attack the rust. I've not been aware of any fumes but I tend to do this type of thing in the garden anyway, well away from tools and machinery.
awemawson:
Electrolysis will give off oxygen and hydrogen in an exactly explosive mix :bugeye:
It is very effective where the rusted parts can be in 'line of sight' of the other electrode. However for 'hidden rust' in things like a nut and bolt still screwed together it is not effective. In this situation citric acid is very effective, as the rust converts to soluble salts which go into solution allowing more to penetrate further into the small gaps between components. Very few of the acids used for rust treatment form soluble salts. Citric acid is very mild and in several years of using it I've not had problems of base metal disolution leaving parts in for extended periods
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