- Thread starter Kayos
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, adding a lot of Fairly Liquid does not change the pH of tap water, but best use alcohol as a wetting agent.
ronan
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I used citric to strip this old mudguard from the 1930's. But the citric acid ate into it ! So beware. I did not have a container big enough to take the whole thing. So i found an old plastic toolbox i no longer used, cleaned it out, filled it with hot water from the tap and put in about quarter of a cup of acid into it and mixed well. The whole guard would not fit into the box, so i did the bottom end which was worse first, then switched around.
The mark is deep enough to feel with your fingernail. I don't care particuarly as i am going to slather it with epoxy primer and fill any marks before paint anyway.
The mark is deep enough to feel with your fingernail. I don't care particuarly as i am going to slather it with epoxy primer and fill any marks before paint anyway.
Ross365
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The whole business of de-rusting things has elements which are hard to fully control. Ideally, you'd start by thoroughly degreasing everything, so that the citric reacts uniformly, and everything would be fully immersed so there are no electrolytic effects at the liquid surface, and agitating/stirring the solution would be good for a variety of reasons. Adding chloride (in whatever form) will speed things up, but may well encourage rust to return. The whole thing also depends on temperature and the surface area (of metal) to volume (of solution) ratios.
I must get around to experimenting with central heating protector to see adding a drop will inhibit citric form attacking metal, but anyone else should feel free to try that idea
I must get around to experimenting with central heating protector to see adding a drop will inhibit citric form attacking metal, but anyone else should feel free to try that idea
ronan
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The whole business of de-rusting things has elements which are hard to fully control. Ideally, you'd start by thoroughly degreasing everything, so that the citric reacts uniformly, and everything would be fully immersed so there are no electrolytic effects at the liquid surface, and agitating/stirring the solution would be good for a variety of reasons. Adding chloride (in whatever form) will speed things up, but may well encourage rust to return. The whole thing also depends on temperature and the surface area (of metal) to volume (of solution) ratios.
I must get around to experimenting with central heating protector to see adding a drop will inhibit citric form attacking metal, but anyone else should feel free to try that idea
I was watching one of Hentry Coles many many programmes on the telly last week. He asked Allen Millyard whats best for getting rust out of motorcycle petrol tanks. He reckoned nothing beats mollasses mixed with water ! Anyone tried that ? I think he said one part Mollasses to nine parts water.
Onoff
In the land of the unfinished project I am King!
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Allegedly if you have the time then molasses is supposed to be really good. Sure I read on the lines of drop it in and come back a month later.
Ross365
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Yes, it seems that molasses works but is pretty slow. In terms of cost, ease of availability and various other factors, citric is hard to beat. Increasingly, I'm convincing myself that if you paint citric on to some really thick, hard rust, leave it 24 hours and then come back with an angry grinder, the rust is easier to remove than if you hadn't done the citric pre-treatment. A bit hard to prove though. I've just done it around the inner edge of a brake disc, and brake disc rust is bloody hard rust!
Onoff
In the land of the unfinished project I am King!
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I'm debating whether to immerse this old sickle in citric acid or not. Thinking that electrolysis might be better on what is quite frankly "good old steel". There's something quite different about it from say the modern steel RSA, PFC sections I've been cutting of late. I don't want to lose it's edge literally and metaphorically. Not sure what hardening went on originally if any. I learnt the hard way with citric leaving my Record plane blades in too long and it knackered/ate the hardened edges.
ronan
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ronan
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A good steel sandwiched between two layers of cast iron according to Ken in the Video above.
Onoff
In the land of the unfinished project I am King!
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Did a load of bits from mild steel black nuts and bolts to Allen keys, easy outs and taps/dies. Most had a little, some a lot of rust on. All taken out and rinsed in hot soapy water then sprayed with RP-90:
Few more random bits bubbling away:
Few more random bits bubbling away:
Matchless
I started with nothing, still have most of it left
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Just got my citric acid delivery, never used it before, going to de rust my Jag petrol tank interior after blasting to remove the worst of the lumpy bits,
question for now is for small parts could I use citric in my ultrasonic cleaner and if so what temperature?
question for now is for small parts could I use citric in my ultrasonic cleaner and if so what temperature?
Onoff
In the land of the unfinished project I am King!
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I maintain my citric acid solution at 70degC via an old central heating cylinder stat. Just following what the Deox-C instructions said that at that temperature it allows very rapid derusting...and it does.
My mate is just embarking on a tank for small parts made from an old chip fryer.
Ross365
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There's no reason why you cannot run at 70'C, but personally, I've never gone that high. Accepting that some metal gets dissolved while the rust is being taken off, once that metal is gone there is no putting it back on. It's very rare that I find myself needing to do urgent de-rusting. Citric will work at room temperature and might well double the rate of reaction with every 10'C increase in temperature. I don't often go above 35'C.
I just cleaned up some new 1/2" wood bolts that had got some surface rust in storage. 10 minutes in citric at 70 degrees & they came out spotless! After a quick rinse in plain water I swirled them in a tub of WD40 & left them to dry. The finish was identical to the original black phosphate finish.
