[vincent]

Hello all,
I have  joined this forum 5 minutes ago and intend to get all my chemistry related questions answered by all of you.
I know very little about  chemicals but use some of them for work purposes almost every day.

Here is my concoction that I have been making up at work for the last 34 years.

Mix 60cc's nitric acid and 40cc's hydrochloric together. Stir well.
Add  fine steel wool until the acid mix is saturated and will no longer dissolve any more steel wool.
This produces a filthy brown sludge.
Add this sludge to 800cc's of distilled water. Stir well.
Strain through a normal coffee filter.
Let stand for 2 days. It is now ready for use.

I then apply this mix to degreased steel to generate a fine grain controlled rust.
When the rust has formed (12-24 hours) I boil the steel parts in water which turns the red rust black.
I then polish the black rust with fine steel wool and repeat the rusting process.
The steel gets darker in colour every day.
This goes on for about a week until the steel stops rusting.
The finished colour on the steel is an extremely pleasing deep blueish, black colour. 

My questions are:
Has my concoction got a name and if so is it available ready made?
After I have added the iron, is it still acidic or has it become alkaline or maybe a neutral PH?
After it has stood for a day or 2 it separates into a clear liquid at the top and a sludge at the bottom.
Which is the part that is causing the rust? The sludge or the clear liquid? I always shake it before use.
Will my concoction decompose and break down over time and lose the rusting ability?
I have been told I should use iron powder and not steel wool as the wool might have aluminium in it. Is this true?
I have posed these questions to local chemists but always get complicated answers that do not give me what I want.
Please help.

Thanks in advance,
Vincent.
 

[Arkcon]

Hello all,
I have  joined this forum 5 minutes ago and intend to get all my chemistry related questions answered by all of you.
I know very little about  chemicals but use some of them for work purposes almost every day.

We're glad to help a novice learn more.  We like to help people learn to help themselves, that's in the forum rules, so we hope you won't mind if we try to help you learn some things for your self by asking you questions.

Here is my concoction that I have been making up at work for the last 34 years.

That's an awesome recipe that you've provided.  And I'm glad we have it here for the next novice to learn from.  So thanks.

My questions are:
Has my concoction got a name and if so is it available ready made?

It looks to me like you start with some derivative of aqua regia, although the proportions are a little off.  No problem however, you can look up that mixture's properties.  And it would be good for you to learn them, for your safety.  http://en.wikipedia.org/wiki/Aqua_regia  Suffice it to say, you have some strong acids and a powerful oxidizer.  No, this stuff isn't sold, it degrades over time, so has to be made fairly fresh.

After I have added the iron, is it still acidic or has it become alkaline or maybe a neutral PH?

Probably still slightly acidic, as most solution of transition metals are.  Maybe you should dilute some, and check.  With pH paper, or a pH meter.

After it has stood for a day or 2 it separates into a clear liquid at the top and a sludge at the bottom.
Which is the part that is causing the rust? The sludge or the clear liquid? I always shake it before use.
Will my concoction decompose and break down over time and lose the rusting ability?

There's lots of varied chemitry happening here.  You may be able to figure it out by Googling specifically, now that you know what the reagents really are, and how they work.  Or an expert may jump in.

I have been told I should use iron powder and not steel wool as the wool might have aluminium in it. Is this true?

I'd never heard that before.  You're going to get some other, different chemistry, if that's the case.  Do you think you're getting problems because if it?  You can buy pure iron fillings, instead of steel wool.  That might give you better results.

I have posed these questions to local chemists but always get complicated answers that do not give me what I want.
Please help.

Thanks in advance,
Vincent.

Well, you're going to get complicated questions here, as well.  You might want to share some of what you know, and see if it can help us understand what you need to know.

[vincent]

Thanks for your reply Arkcon.

It seems I must make it up in smaller quantities and use a fresh mix for each batch of blackening that I do.

Based on my post I will be impressed if anyone recognises the industry I am involved in and what I am blackening.