Evaporust - first time user / review

[Dcal]

How come yours does not stay black?

I've not use evaporust, I used citric acid, I didn't fancy paying for a 100l solution of evaporust. There's over £30 worth of citric acid in the bin as it is.

On mild steel, it just pressure washed off.
I think you need to wash before it dries, however different metals and steels react differently.
If it dries before washing it doesn't come off the same.

I dipped some rear discs and caliper brackets and they didn't wash up as well and left a coating.

My guess (and it is a guess not based on any scientific understanding) is it's down to the carbon content, so if your collets are high carbon steel, it could be the cause.

On the discs and cast steel a coating stayed after washing, but it rusted off pretty quickly after they were dry.
The discs did come out well and uncovered the manufacturer's laser marking.
I'm going to ceramic coat these bits to see how they last, but they will be blasted first.

I'd leave the black on the collets, I can't see it doing any harm and might even help protect against rusting.

 

[Dcal]

I think what concerns me is that the effect of leaving chloride on the surface won't show up in a week or a month, but more likely, a year or two.

What experimenting I've done in the DIY context, I have shared on this forum and others, and can be summarised as follows;
>I've been a big fan of citric for years ( I first read about it in the early 1980's)
>I've been a huge fan of zinc phosphate primer for years (note how eventually, they started putting zinc phospahte in expoxies!).
>I've had mixed results with phosphoric acid (no longer using it regularly)
>I've had mixed results with electrolysis
>I'm on a learning curve with my grit-blaster and needle gun.

I've not tried Evaporust; it looks good, not sure I'll leave citric for it, but open to persuasion.

10 minutes ago, I was painting a brake caliper. It's a new one with shiny plating (which does not last!!!), so that was primed with Hammerite Speciality Metals primer (possibly the only product that company now makes that's worth using) and then a black gloss top-coat.

This is experience which started by owning a Vauxhall Viva back in the 1970's; cars rusted a lot back then. The two cars I have at the moment are both over 20 years old, and get by MoT's with no advisories on corrosion. When I work on my cars, I assume and intend they will still be around when I'm gone, so a problem that will show up in 2 or 3 years is a problem. I also read a lot of technical papers and text books on corrosion (I've recommended certain books on this forum).

A huge amount of time and money has already been spent researching corrosion, which has given rise to damage costing many billions for many decades. The progress that has been made shows when you compare the corrosion resistance of a 1960's car with a modern one .

I've had a similar car journey to you. My first car was a Viva HC, but I wised up and quickly moved on to twin cam fiats so have years of experience of rust.

I also have the same concerns as you on contaminating the metal before coating.
I don't trust any of the converters and wouldn't use anything like acid unless I can get the most of it out before painting or where I can't blast, so have no other reasonable option.
I don't have the means to test for residual salt levels so can only guess and how quickly the steel gingers up and the colour of the rust is the best guide I have.

I've been around marine structures most of my working life and by and large I stick to the industry standard of, removing all sharp edges, pressure wash to reduce salt levels to an acceptable level, grit blast, 2 thick coats of epoxy mastic and a PU top coat.

I don't see any approved off shore systems that use zinc phosphate, but if it works it works.

I buy industrial paints because they are tested and certified.
If they change the formula they retest and recertify the system so it is at least as good as the the system they are replacing.
With DIY type paints, they can change the formula without telling you so you never know where you are.

 

[ukracer]

I've had a similar car journey to you. My first car was a Viva HC, but I wised up and quickly moved on to twin cam fiats so have years of experience of rust.

I also have the same concerns as you on contaminating the metal before coating.
I don't trust any of the converters and wouldn't use anything like acid unless I can get the most of it out before painting or where I can't blast, so have no other reasonable option.
I don't have the means to test for residual salt levels so can only guess and how quickly the steel gingers up and the colour of the rust is the best guide I have.

I've been around marine structures most of my working life and by and large I stick to the industry standard of, removing all sharp edges, pressure wash to reduce salt levels to an acceptable level, grit blast, 2 thick coats of epoxy mastic and a PU top coat.

I don't see any approved off shore systems that use zinc phosphate, but if it works it works.

I buy industrial paints because they are tested and certified.
If they change the formula they retest and recertify the system so it is at least as good as the the system they are replacing.
With DIY type paints, they can change the formula without telling you so you never know where you are.

Mine was a white HA that I painted black with a brushed tekaloid.

 

[6ply]

Please excuse me if this is a terrible idea, but would a tumble roller (screw top drum) filled with parts, a handful of aggregate, and some citric acid solution be a viable mix to derust and clean up corroded small parts? Easy enough to make a couple of slow running rollers.

 

[steveo3002]

Please excuse me if this is a terrible idea, but would a tumble roller (screw top drum) filled with parts, a handful of aggregate, and some citric acid solution be a viable mix to derust and clean up corroded small parts? Easy enough to make a couple of slow running rollers.

the citric works well on its own , if anything invent a way to keep it warm as it works faster

 

[ukracer]

Please excuse me if this is a terrible idea, but would a tumble roller (screw top drum) filled with parts, a handful of aggregate, and some citric acid solution be a viable mix to derust and clean up corroded small parts? Easy enough to make a couple of slow running rollers.

I have a ready built roller but I am worried it will alter the spec of the collets if I tumble it.

 

[6ply]

I have a ready built roller but I am worried it will alter the spec of the collets if I tumble it.

Understood, but I was considering non precision components.

 

[ukracer]

Ok revisiting this again.
I had some fresh evaporust come today. And I tried a collet in it.
It's gone even blacker but seems to have left , what is possibly surface rust or other bits of crud.
Not sure what will show up on these photos but I am dodging between tasks and this poxy rain again.

Has anyone found anything that will remove the black colour left by evaporust.

And what is the consensus on using a tumbler with a polishing grit/powder with just one collet at a time.
I suppose its more a case of if the black has impregnated the steel. If it has I guess only a chemical might remove the black.

I am not actually overly concerned about the collets being black but more about knowing the limitations of evaporust on aesthetic items.

 

[Sergei Slovenija]

Ok revisiting this again.
I had some fresh evaporust come today. And I tried a collet in it.
It's gone even blacker but seems to have left , what is possibly surface rust or other bits of crud.
Not sure what will show up on these photos but I am dodging between tasks and this poxy rain again.

Has anyone found anything that will remove the black colour left by evaporust.

And what is the consensus on using a tumbler with a polishing grit/powder with just one collet at a time.
I suppose its more a case of if the black has impregnated the steel. If it has I guess only a chemical might remove the black.

I am not actually overly concerned about the collets being black but more about knowing the limitations of evaporust on aesthetic items.View attachment 409745View attachment 409746

IMHO, you overexposed the part in solution, and this is black carbon. Micropitting.

It will similarly corrode the surface of hardened tools (slightly rusty drills, taps, reamers) with EDTA if the exposure is greater than necessary. I have ordered 10kg of EDTA (with Na2) for flushing heat exchangers, and will try it to clean rusty parts, but I know that it is possible to damage the surface of the instruments with overdose of salt, exposure time and temperature.

 

[jonclancy]

It was a while ago, but I think I had this with one of the solutions I was using. I can’t recall, but I do know that the calcification (as was in that case, and what it resembled) was removed by new solution. I’d try a quick dunk in warm citric, and a brush over.

Good luck!

 

[Ross365]

Something that I've started looking in to is finding a corrosion inhibitor for citric (and would probably work with EDTA), which is to say, a compound which does not affect the dissolution of rust, but inhibits any attack on the underlying steel. You can certainly find reference to such inhibitors on Google, but it seems that they often only supplied in industrial quantities, and typically, you only need to add one or two parts per hundred. The other possibility might be to buy a bottle of something like Fernox heating system inhibitor and try a small amount of that.

 

[Sergei Slovenija]

Something that I've started looking in to is finding a corrosion inhibitor for citric (and would probably work with EDTA), which is to say, a compound which does not affect the dissolution of rust, but inhibits any attack on the underlying steel. You can certainly find reference to such inhibitors on Google, but it seems that they often only supplied in industrial quantities, and typically, you only need to add one or two parts per hundred. The other possibility might be to buy a bottle of something like Fernox heating system inhibitor and try a small amount of that.

Share the names. I'll also look for available options. I know urotropin (tableted Solid fuel)

 

[Ross365]

As they weren't of immediate interest, i didn't keep good notes, but one that I did record was Cortec VpCl-337, which I think may be a French product.

 

[Sergei Slovenija]

As they weren't of immediate interest, i didn't keep good notes, but one that I did record was Cortec VpCl-337, which I think may be a French product.

Judging by the range of applications, it is similar to a surface corrosion inhibitor, such as:
N-azole, N&S-azole (i.e., thiazole), and N and O-azole, 2,4-disubstituted oxazole (i.e., oxazole) etc.

For preservation of metals during storage and transportation. Not for aqueous solutions.

 

[Dcal]

I think the citric acid has some corrosion inhibiting effects.
It might be slight but it could be useful for extending the length of time you have before you need to apply a coating.
It might also cause long term performance issues with the coating but I've no way of proving (or disproving) this in the short term.

I dipped some brake discs and one of the discs wasn't submerged fully in the solution.
I pressured washed the discs and they rusted slightly when dry.

I then blasted the non wearing parts of the discs, in advance of ceramic coating.

However, I didn't get around to coating them for a couple of days and they held up very well except for the tiny bit that wasn't dipped in citric acid.

I've no idea what's going on but I do find it interesting.
Any chemists in the house?

 

[Ross365]

Rusting is a strange subject, and really quite complicated. I once recall a big argument getting started between the company I worked for about "flash rusting"; we had never seen it on these particular components, but they said it happened all the time and was damned hard to stop.

 

[JOEPRO]

I'm still dunking stuff in the original portion of Evaporust. It's turned very dark / black now but is still working.

I'm also going to pick up a parts tumbler tomorrow. That will be handy for prepping bolts, nuts and small parts for paint or zinc plating.

 

[Sergei Slovenija]

Acquired 10 kg of EDTA + tableted dry fuel as a corrosion inhibitor,

(MethenamineC AS: 100-97-0)

 

[Ross365]

Acquired 10 kg of EDTA + tableted dry fuel as a corrosion inhibitor,

(MethenamineC AS: 100-97-0)

View attachment 411129

Oooh, interesting. What concentration you going to use? I think what I've seen suggests just a few millimoles is required, though more is probably acceptable.

 

[Sergei Slovenija]

Oooh, interesting. What concentration you going to use? I think what I've seen suggests just a few millimoles is required, though more is probably acceptable.

In terms of the inhibitor, I think 0.2%, approximately. EDTA 10% per litre.