I give up!

Colouring processes for metal and other materials.

I give up!

Postby Steve P » Thu May 26, 2011 8:11 am

Im going to chage to a different steel. Ive held off doing any more tsuba work till I can get a patination right and Ive concluded that the stuff Ive used till now is part stainless. This has been etched cleaned in acetone then submerged in salt water for 3 months :grrrr:
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Re: I give up!

Postby Ford » Thu May 26, 2011 8:41 am

Steve,

it may be that your approach is too aggressive...typical Aussie bloke :smartass:

Try this; heat the plate to red heart and allow to cool slowly. Remove the scale by immersing the plate in hydrochloric acid for a few minutes. Don't leave it alone as it shouldn't take long, maybe 5 to 10 min. The acid won't really attack the steel at this stage and tend only to remove the scale/oxide layer. If you wear rubber gloves you can periodically remove the plate from the acid and brush off the sludge with an old toothbrush. Take care not to splatter yourself with acid....eyes and clothes don't respond well :?

Once the plate is free of oxides and looks a frosty pale grey remove it from the acid and swill in clean water. Just a quick dip in the water is all that's wanted. Shake off any water droplets but don't dry. Now hang it on a bit of steel wire and leave it overnight.

As you're in a very dry environment it might be an idea to suspend the plate in a sealed plastic bucket or something similar. Some crumpled up damp newspaper in the bottom might be helpful too.

Within 24 hours you should have a fine and very adherent layer of rust on the plate. You can take a fine steel wire brush to it and scrub off anything that will come off. If all's gone as planned the surface will be very hard, quite glassy and dark brown. Repeat the rusting process if the covering is still patchy. Once you've got that far take some pics and post them here for further tips on finishing :)

Good luck,

fh 8)
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Re: I give up!

Postby Steve P » Thu May 26, 2011 9:41 am

Phew... thanks Ford, the quiet voice of reason.
Ill try that.
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Re: I give up!

Postby Patrick Hastings » Thu May 26, 2011 8:09 pm

I also use hydrochloric acid to prep my iron plates. It I wait for that frosty uniform grey to develop take it out for a quick dip in clean water. I pat it dry with a paper towel. I live in a damp part of the world so I just hang it on the "pati-natering" wall. Within minutes its starts to turn color. By the next day it needs a rub down. If its raining out (and it does this quite a bit here) then it will just continue to slowly rust everyday on its own. If its a dryer day then a bucket like Ford mentioned works well.


The formation of Rust is an electrical process. Water is technically not conductive unless it has something dissolved in it so the salt or salts provide you with a conductive fluid. This electrolyte connects individual iron crystals to each other across the surface. There is a very tiny galvanic difference between each crystal grain exposed to the surface (and any potential oxygen). So the surface will get covered with tiny micro galvanic reactions. This is how rust works.
The tiny pits you see when something has been rusted are actually the anodic parts of the microcells. Its where the metal is being stripped out of one half of the cell then the other half collects some iron oxide or rust. Since the shape and volume of the cells change so does there galvanic hierarchy. The pattern of cells jumps around. Eventually creating what appears to be a fairly even field of rust
Moisture is the critical component here and it helps to have some type of salt present on the surface for the iron to make the water into an electrolyte. Some salts are hygroscopic and will literally collect moisture from the atmosphere. So you get lots of moisture and an electrolyte and rust grows quickly.
The acid that we use to clean the steel also leaves behind a trace of salts. Moisture from the atmosphere does the rest as long as there is enough... Thats why if you over rinse it it won't work as well. You will remove too much of the acid salt traces.

Patrick :)
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Re: I give up!

Postby Steve P » Thu May 26, 2011 10:15 pm

Thanks Patrick.
I used HCl and ferric cloride to etch the plate and a soak in acetone in case Id touched it. No go the thing still only rusted in patches. Other areas are bright and shiny after weeks in a warm salty moist atmosphere.
It is puzzling and very frustrating.
Perhaps I should find some of the steel that Fiat and Alfa Romeo used in the 70s to make their dissolvable cars ;)
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Re: I give up!

Postby Lorenzo » Fri May 27, 2011 6:14 am

Steve P wrote:Perhaps I should find some of the steel that Fiat and Alfa Romeo used in the 70s to make their dissolvable cars ;)


Ah, let an Italian reply to this; you don't need to go back 40 years in the production line :crackup:
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Re: I give up!

Postby Steve P » Fri May 27, 2011 7:10 am

Yeah, I own a Fiat. I thought I had rust sorted :biggrin:
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Re: I give up!

Postby Lorenzo » Fri May 27, 2011 7:14 am

You should know how to stop the red rust with this forum, you can now have a nice sabitsuke car, put some nunome zogan on it and voilà, you will have the first higo car.
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Re: I give up!

Postby Kevin » Wed Jun 01, 2011 2:25 pm

Steve, I hope you don't mind if I jump in here, as I've also been having trouble getting an even, adherent rust coating and REALLY want to move away from using gun blue :pray:

I've attached a photo below of a project I have underway. Preparation was as follows (modified slightly from the above direction):

- scrubbing of the completed tsuba with a toothbrush and abrasive cleanser (Comet)
- a 15-minute soak in acetone followed by another (clean) toothbrush scrub
- rinsed with water and patted dry
- a 5-minute soak in muriatic acid (I couldn't find a higher concentration of hydrochloric acid, unfortunately)
- a quick dunk in water, shaking off the droplets
- suspended on a bent coat hanger in a plastic bucket above some crumpled damp newspaper

I was very pleased to see rust forming almost immediately when I stuck the tsuba in the bucket (first photo). The second photo is after 24 hours - I wasn't sure what Ford meant by the rust coating looking "glassy", but I see it very clearly now (you can't really see it in the photo). What exactly is happening?

Akasaka_rustbucket.jpg

Akasaka_init_rust.jpg


Now, I haven't brushed off the loose rust yet - I'll do that after work (I didn't have any degreased steel wool on hand, so it's currently drying after being dunked in acetone this morning :P). But I would welcome any comments at this early stage, as it is a little patchy yet. My assumption is that once the loose rust is removed, this will "encourage" more to form, and thus even out the coating.

A question though: what constitutes a "repeat" of the rusting process? Simply leaving the tsuba in a humid environment? We're not due for any rain anytime soon, so should I mist the tsuba when I stick it back in the bucket? After reading Patrick's explanation of the reaction between salts and moisture, should I try to increase the salinity of the water in my bucket?

Sorry for all the questions, I realize that I should just leave the tsuba to just "do its thing" for a few weeks, but I'm curious to know what's actually happening and be able to nudge things in the right direction if necessary :)

Thanks!
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Re: I give up!

Postby Lorenzo » Wed Jun 01, 2011 5:49 pm

I love your tsuba Kevin.
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Re: I give up!

Postby Kevin » Thu Jun 02, 2011 2:18 am

Thanks Lorenzo - I had hoped to show it AFTER resolving my patina issues, but it was not to be :(
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Re: I give up!

Postby Patrick Hastings » Thu Jun 02, 2011 6:30 am

Unfortunately salt in the water soaked newspaper is left behind as the water evaporates. So Salting the water there will not help seed the micro cells.

What I see in your pic is (a lovely Tsuba BTW) A much too aggressive rust. You have the orange powdery areas these are perfect! The darker "dried blood" color areas are where the the action was too aggressive. Once this happens on mine I strip it with another acid bath to start over. I want that powdery orange to develop. The timing here is it needs to be rubbed down before any of the darker patches or spots form. If they are forming too quickly then there is too much moisture present. In a closed container you literally only need a few drops. Watch and make sure that no visible condensate forms on the Tsuba at anytime. Droplets will cause the darker and thicker crust to form. Everything eventually comes back to the same darker color, but those early dark crusts will always be thicker than the surrounding area leaving them visibly raised in the final patina.

One method (if nature is not cooperating) is to recharge the salts on the Tsuba. You don't want to use the acid obviously since it will simply dissolve your efforts. There are a bazillion salts and combinations for this.

I have found that you can take your old muriatic and drop some low carbon steel in it. Stir it frequently Make sure it's acidic effects are completely killed by the iron. I go for a couple weeks to be sure. You should end up with a clear yellow green tinted fluid with a white silt that has settled out on the bottom. Separate the fluid from the silt through a coffee filter or by simply pouring the fluid off without disturbing the white stuff at the bottom.

The resulting fluid has the salts, but its ability to strip the rust is nearly gone. Apply with earbud only a very light even coating. It should look moist for a moment, but not wet. It should look dry again in less than a minute that is about how thin you put it on.
It's all down to controlling the salts and the moisture. Keep tuning until you get just enough orange rust every 12 to 24 hours to rub down. But not so fast that you get any of the uneven darker clusters forming.

Patrick :)
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Re: I give up!

Postby Ford » Thu Jun 02, 2011 8:43 am

Hi Kevin,

The glassiness I referred to comes about after the surface has been scrubbed with a steel wool or similar.

Why did you dunk the tsuba in acetone, btw? :naughty: ;) You chaps are obviously using actetone to degrease but it's not necessary, imo, if the other steps have been carried out correctly. Also, if you're using acetone as used as nail polish remover it contains lanolin, sheep wool oil! Obviously this is comforting to Antipodeans but it'll get in the way of rust formation :smartass: . Seriously though, I don't know enough about the interaction of acetone and Fe but something makes me think acetone is "greasy" in the sense that some sort of residue is left on the steel that inhibits normal rust formation. If you use acetone on non-ferrous metal before patinating you'll inevitably see streaks and blotches redevelop in the patina.
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Re: I give up!

Postby Kevin » Thu Jun 02, 2011 2:14 pm

Ford wrote:You chaps are obviously using actetone to degrease but it's not necessary, imo,

Guilty - I remember reading somewhere either here or on the Carving Path about using acetone as a degreaser, and have been using it due to my increasing obsession with a clean plate prior to patination. When I re-start the patination on this, I'll omit that step :redface:

Patrick - THANK YOU THANK YOU THANK YOU for the exacting analysis of what's happening. It sounds like I should use less water/newspaper in my "humidity bucket" and keep a closer eye on what is going on with the rusting progress. Now that I know what I'm looking for, things should progress a little better. Now that you mention it, I probably didn't shake off enough water after the acid bath, as there were "collections" of water on the insides of the sukashi. Something to keep in mind.

Also, an interesting point about subsequent uses of the acid to recharge the salts on the surface - I did ponder how to do this after your explanation of how they interact with moisture. After work I'll dive into restarting the rusting process, and keep the acid I use for use in the manner you describe.

And thanks for the comment about the tsuba itself - I'm hoping that the patina (when/if I get it right) will accentuate the texturing I did on it. It was a laborious process of sawing, filing and hammering - truly a "bit off more than I could chew" project :P
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Re: I give up!

Postby Patrick Hastings » Thu Jun 02, 2011 6:42 pm

ditto on the acetone, don't bother with it. It can even make it worse.

I don't think it is greasy in an off itself, as it evaporates completely. However it does not take with it anything that it has dissolved. When it evaporates it leaves behind a thin remnant of whatever it was you were trying to remove. If you used it before then its contaminated and will certainly leave a residue. The residue can actually behave like a lacquer since the Acetone leaves it behind in a different way than when it first came off.
In order to use it successfully too degrease you have to continually use fresh acetone. Use clean paper towels to apply it and wipe away continuously using fresh paper towel and fresh acetone. This will get things pretty clean and finally a dip and swish in two separate fresh acetone baths.

Eventually you get the greases so dilute that the part is "degreased". All that acetone has to be thrown out as it is all contaminated now with traces of grease. Its ends up being pretty wasteful in this application and most importantly as Ford mentioned it completely unnecessary.

Patrick :)
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