Citric acid derusting

[Onoff]

You can see how the acid dipping process can ruin monocoque car bodies when it gets in between lap jointed panels and seeps out later. I shudder when I recall the pictures of a 280 Capri that had had it done.

 

[Kram]

An hour or two, not days!
Looks like solution became exhausted or fully saturated or I doubt thered be anything left. A short dip in fresh should clean them up, Im interested to see the result.

Ive found cold is not much good, you need to leave it a lot longer and get more pitting.
Hot citric, pull out every hour to wipe the surface clean. Any build up of greasyness on surface will impair the reaction.
If its just surface rust like collets, Id check every 20 mins.

 

[Agroshield]

The 3 cutting wheels in the pipe cutter have "rivetted" shafts.

Have a good look at them before drilling. On a couple that I have dismantled, one end of the wheel-retaining pin is splined or coarsely knurled, a bit like like a car wheel stud, and is just a snug fit in its mating component. Drifting it out from the opposite end to the spline removed it.

 

[GSR]

How long does citric acid keep for before losing its effectiveness, and is there any particular way to store it to preserve it?

 

[bigegg]

How long does citric acid keep for before losing its effectiveness, and is there any particular way to store it to preserve it?

Keeps for ages in a sealed (plastic or other non-metallic) container.

 

[GSR]

Keeps for ages in a sealed (plastic or other non-metallic) container.

Thanks

 

[Onoff]

So what's the best way to dispose of a 180L bath full of depleted citric acid?

On the garden, on that patch where I'm planning to extend the shed, down the unmade drive?

No main drainage here and I don't want to put it in the cess pool.

 

[Kayos]

So what's the best way to dispose of a 180L bath full of depleted citric acid?

On the garden, on that patch where I'm planning to extend the shed, down the unmade drive?

No main drainage here and I don't want to put it in the cess pool.

If you tip it on the grass it upsets the worms and they all come to the surface

 

[Onoff]

If you tip it on the grass it upsets the worms and they all come to the surface

It's the slow worms I don't want to upset!

 

[Onoff]

Is it possible to use pH test strips when you first mix up a batch of citric acid then later to see how depleted it's becoming?

 

[indy4x]

The black stuff that accumilates on the surface I usually wash of with a pressure washer

 

[Ross365]

So what's the best way to dispose of a 180L bath full of depleted citric acid?

If the acid is depleted, the question there is not citric acid, but the iron/rust which has been released. How many grams or kilograms of iron crap is there in 180L?

Of course, ferrous sulphate is used to kill moss and darken grass. Wonder what ferric citrate might do to moss? Sadly, I suspect that the official answer to your question might invoke the use of some chemical waste company.

 

[MattF]

If you tip it on the grass it upsets the worms and they all come to the surface

Water has that effect on them. Can remember our infant or junior school teacher telling us that birds go after worms during rain for that fact.

 

[Hood]

Water has that effect on them. Can remember our infant or junior school teacher telling us that birds go after worms during rain for that fact.

Seagulls dance on the ground as it sounds like rain to the worms so they come to the surface and get snaffled by the gulls.

Edit, probably the vibrations rather than sound as I don't think worms have ears

 

[Hood]

Ok just tried it and looking good so far.

Collet before

Some hot tap water, couple of tablespoons of citric acid and 10mins later this.

Have put it back in and will leave for a bit longer to see what happens.

 

[Hood]

Taken it out now after just over an hour they look like this.
Extremely happy and although they have a dull grey finish it is quite pleasing, certainly more so than the brown rust

 

[Onoff]

Taken it out now after just over an hour they look like this.
Extremely happy and although they have a dull grey finish it is quite pleasing, certainly more so than the brown rust

View attachment 282547View attachment 282548

You need to watch for flash rusting as aforementioned. Hot air gun them dry then oil asap.

 

[MattF]

You need to watch for flash rusting as aforementioned. Hot air gun them dry then oil asap.

A quick dunk in boiling water is best. Neutralises the acid, & heats the piece up so that the water evaporates on removal.

 

[Onoff]

I didn't worry about the little bit of flash rust on the adjustable body. Just hit it with the etch primer then an acrylic top coat. It was "blue" to start with. Took longer to mask up than de-rust it!

The small Kamasa adjustable I found rusting away on site just got oiled and greased after the citric.

@Agroshield , yep, pins drift out. Cheers for that...well two have, must find the right size punch. I need new cutting wheels really. This will have a good old detergent clean then another dip.

 

[Onoff]

My college made V blocks had a quick dip. Tbh I have used them on and off over the years so not in too bad nick.

The vice I made that's sat in the citric since Nov 2019 looks salvageable. Can't turn the handle yet mind. For now it and the blocks have just had a dip and a quick coat of penetrating oil.

I seem to recall the vice always had a tight spot. I remember I cut the lead screw on the lathe all those years ago. M12 X 1.75 maybe? Perhaps running a die nut down it and a tap through the other bit might sort it. I've still got my EITB drawings for everything somewhere. Always seemed a bit of a useless vice without a base plate.