Taps and dies rust removal

[Roger440]

Things going black is my experience with Dex-C & citric acid tbh. A pig to get off and gets on your hands and everything else. A couple of thoughts:

1) Is the concentration, as in powder to water a factor?

2) That we seem to have different experiences, is hard / soft water an issue?

3) Gut feel is the type of steel is a big factor, maybe the higher carbon content stuff goes blacker? That's me just guessing

I've even tried a few drops of Fairy Liquid to assist lifting the sludge coat during and after.

I wonder if a fishtank aerator would help keep the black stuff mobile in the solution and at the same time speed the process up? A bit like a PCB bubble tank for etching.

Ive not found the concrentration making any difference.

However, i agree the steel type is a factor. Castings make stuff go black, fast.

Like the aerator idea. Must try that.

 

[Memmeddu]

Things going black

A rust patina forms and react due to heat forming FeO4
Rust blueing

 

[Roger440]

A rust patina forms and react due to heat forming FeO4
Rust blueing

Ive just done a steel undertray.

On thursday, i put it in my tank with the fishpond heater, which gets the deox-c to aboyt 35 degrees.

Took it out and rinsed it. Mostly bright shiny steel. Few areas were still rusty thoug. So put it back in all day friday. Whilst it had removed pretty much all the rust, this time, it was black, all of it.

Im trying to figure out why it was initially nice and silver, but now black on the second go?

Ideas?

 

[ahebron]

This is the evaporust I use

Evapo-Rust Rust Remover

Restore your rusted tools, car parts and garden equipment to their former glory with Evapo-Rust® - a powerful, water-based rust remover that's reusable and non-toxic.Evapo-Rust® safely and easily removes rust without the need for scrubbing or sanding, saving you time and effort. It couldn't be...

www.toolstation.com

 

[Turbo]

A rust patina forms and react due to heat forming FeO4
Rust blueing

I dip the item in hot citric for a few minutes.
When the rust is gone rinse the citric solution off with hot water and straight into a tub of wd40 until it cools.
Take it out, let it drip off for a few minutes.
Wipe off any remaining liquid and leave it overnight to dry.
The wd40 sets the oxide coating and leaves an oil blackened finish.

 

[Memmeddu]

trying to figure out why it was initially nice and silver, but now black on the second go?

It reacted with the oxygen into warm water forming FeO4.
Rust blueing was really popular for guns many years ago...
You take a clean still part, you degrease it, then you apply a mild corrosive solution to develop an even surface rust coat, scrub and boil the part in water

 

[Roger440]

It reacted with the oxygen into warm water forming FeO4.
Rust blueing was really popular for guns many years ago...
You take a clean still part, you degrease it, then you apply a mild corrosive solution to develop an even surface rust coat, scrub and boil the part in water

So why not the first time though?

 

[Memmeddu]

So why not the first time though?

Might haven't had been exposed to enough heat or oxygen to react