Citric acid derusting

[jonclancy]

I got my food grade citric from eBay/Amazon. Can’t remember which. 5Kgs at a decent price delivered throught the usual courier network. It wasn’t an issue.

if you want something less aggressive, try a chelating agent. I had great success with Evaporust. Trouble was, it was VERY expensive, and didn’t seem to last that long. I did have it covered, and the anaerobic microbes ”neutralised” it. But it is PH neutral, IIRC.

 

[Seadog]

if you want something less aggressive, try a chelating agent.

Which is exactly what citric acid is.

 

[Arc Tourist]

Is "Food Grade" citric acid worth getting ? Is it more aggressive for removing rust ?

 

[The_Yellow_Ardvark]

Is "Food Grade" citric acid worth getting ? Is it more aggressive for removing rust ?

No, just cleaner and comes in a tougher bag to avoid damage in transit.

 

[Onoff]

Will do. I am going to see him in the morning so will have a chat with him then. If there is a car coming up then that would work well.

I reckon you'll get critic acid a bit closer to home as food producers use it. Try this lot:

Orkney – A dreamy taste of reality

www.orkneyicecream.com

 

[Ross365]

Is "Food Grade" citric acid worth getting ? Is it more aggressive for removing rust ?

See my post #196.
I'm always surprised when people say that citric is too aggressive; just make a more dilute solution - there will come a point when it does nothing. I suspect that there are chemicals (i.e. corrosion inhibitors) that could be used in citric that would enable it to deal with the rust, but then come pretty much to a stop when its down to actual metal. I'm sure that the stuff you put in central heating systems to flush out the muck have inhibitors in them. Maybe that's what you pay (heavily) for with stuff like Evaporust; they have done the research and development... or may be not?

 

[James1979]

I reckon you'll get critic acid a bit closer to home as food producers use it. Try this lot:

Orkney – A dreamy taste of reality

www.orkneyicecream.com

Cheers. I do a bit for them from time to time so I know just the guy to ask. Hadn’t thought about it in ice cream....

 

[Arc Tourist]

See my post #196.
...................

Got it, didn't see it before. Thanks.

 

[MattF]

I reckon you'll get critic acid a bit closer to home

Sounds like a wife.

 

[Pete.]

Is "Food Grade" citric acid worth getting ? Is it more aggressive for removing rust ?

The stuff I use is food grade, though time expired so it was being sold off cheap as not.

 

[jonclancy]

Which is exactly what citric acid is.

Oops. Thanks. Just been and brushed up. I have tried Citric, Phosphoric and Evaporust. It seemed that Evaporust didn’t attack metal left in the solution for ages, whereas the other two did after a while.

 

[Turbo]

Oops. Thanks. Just been and brushed up. I have tried Citric, Phosphoric and Evaporust. It seemed that Evaporust didn’t attack metal left in the solution for ages, whereas the other two did after a while.

Phosphoric will dissolve a bolt if you forget about it & leave it in the acid for 2 days!

 

[Ross365]

But, but, but, surely phosphoric is used to produce a rust-resistant surface layer (of iron phosphate), so I would have thought that phosphoric would form that layer and then pretty much stop? Citric does not form a protective layer, but it is a weak acid. I've left steel in phosphoric for a few hours, but not a couple of days.
It may well be that it all depends on the concentration of the acid and the material the bolt is made from?

It's very bothering when stuff you thought you understood turns out to be "uncertain".

 

[jonclancy]

I use an electrolysis bath too. Stuff at home is quite chaotic at the moment, so parts tend to be left in solution. I’ve no worries with the electrolysis bath, but do like to keep an eye on the citric. Stuff left for dead in Evaporust seems to kill the solution, but doesn’t damage the metal. I found the phosphoric does form the layer quite quickly. I did some trailing arms in that before painting. They seemed to go quite nicely. However, a 20:1 citric solution is cheap and works well. Did my Record 84 recently (left for ages, but in and out of the bath). It’s come out a treat. Cleaning up the parts now. I have some axle casings to do. Quicker than electrolysis in a wheelie bin, and I can get three into a plasterer’s bath in one go.

 

[Ross365]

Jenolite used to (possibly still do) sell phosphoric acid in the form of a gel, bit like wallpaper paste. You could brush it on to a vertical surface and it would just hang there, and the acid would diffuse on to the metal.

I reckon that making gels is is not very hard to do and would like to try it with citric, but need a stating point. Anyone (or your partner) knowledgeable about cooking or maybe making home cosmetics and therefore knows about gelling things??? For sure, there are suppliers of materials for making home cosmetics on eBay.

 

[Onoff]

Jenolite used to (possibly still do) sell phosphoric acid in the form of a gel, bit like wallpaper paste. You could brush it on to a vertical surface and it would just hang there, and the acid would diffuse on to the metal.

I reckon that making gels is is not very hard to do and would like to try it with citric, but need a stating point. Anyone (or your partner) knowledgeable about cooking or maybe making home cosmetics and therefore knows about gelling things??? For sure, there are suppliers of materials for making home cosmetics on eBay.

Not tried it but I've heard to make wall paper paste up with your citric solution. Won't it dry though?

I reckon clear, cooking gelatine would do. Or try strawberry jelly, you could see any bits you've missed then...maybe.

 

[a111r]

I'm going to try making it using wallpaper paste.

I have made paint stripper 'gel' with NaOH and cheap porridge oats - that's gloopy alright.

 

[The_Yellow_Ardvark]

I'm going to try making it using wallpaper paste.

I have made paint stripper 'gel' with NaOH and cheap porridge oats - that's gloopy alright.

To stop it drying out, wrap it with cling film

 

[Kram]

I tig'd a bench last week and found it interesting. Left out, the citric stripped tubes are fine, but the flap disc stripped tubes have rust all over. Both welded fine, but seems the citric leaves a thin layer of black oxide that helps prevent any rust.

 

[PhillipM]

Jenolite used to (possibly still do) sell phosphoric acid in the form of a gel, bit like wallpaper paste. You could brush it on to a vertical surface and it would just hang there, and the acid would diffuse on to the metal.

I reckon that making gels is is not very hard to do and would like to try it with citric, but need a stating point. Anyone (or your partner) knowledgeable about cooking or maybe making home cosmetics and therefore knows about gelling things??? For sure, there are suppliers of materials for making home cosmetics on eBay.

Buy some cotton microfibres or silica fume from any local fibreglassing place, add, stir, viola, thixotropic gel.