A. G. Maisey

Our discussion of blade cleaning that was happening in another thread has now been terminated, due to an infringement of Forum rules, however, I feel that the discussion was progressing in a very valuable direction, and that the cleaning discussion should continue.

The penultimate post, entered by Kai, to that now closed thread I felt was particularly useful for new comers to acid cleaning, accordingly, I have copied Kai's post and I have made it part of this opening post.

Posted by Kai here:-

http://www.vikingsword.com/vb/showthread.php?t=23925

and republished here:-

Hello Alan and Ariel,
Quote:
Any mild acid can be used to get rid of rust, I used pineapple juice for a long time, like about 50 years, but then the stuff I was using became unavailable, the substitute was rubbish, so I went to ordinary household white vinegar, the cheapest I can buy.

Industrially produced concentrated vinegar (glacial acetic acid) is usually cheapest (check both the kitchen as well as the cleaning supply!). It comes in concentrations from 10%-99% - beware, the high concentrations are pretty nasty! Dilute down to 1%-5% to start with (yes, pour the concentrated acid into the water rather than vice versa! ).

Quote:
I use a wall paper trough to soak the blades, inspect daily, rinse daily, scrub with various things depending on what needs to got rid of, pick off the hard encrustations with a sadler's awl, sometimes scrape off big encrustations with a small scraper made from a three corner file.

I prefer to work over the blades at least twice daily; I also make sure to thoroughly degrease the blade prior to the acid treatment. If oil shows on the surface, I remove the blade, dry it and degrease again (fittings and crevices can harbor residual oil) - this makes sure that the acid can work on all remaining rust (and, thus, shortening the exposure time).

Quote:
Treatment time can vary from a couple of days to a couple of weeks, I just keep returning the blade to the vinegar until it is clean, sometimes it might be necessary to change the vinegar. I have never known the vinegar to cause any blade damage.

This may be true for the keris Jawa culture. OTOH, acetic acid of any notable concentration will eat away iron (and steel even quicker)! If you compare early collected keris from European collections with their "relic" counterparts that have been traditionally "washed" multiple times, I believe it is fair to say that acetic acid (as in coconut "water"/vinegar) does damage keris blades in the long run. The loss of material may be mainly from removing rust which certainly develops quite quickly in a humid tropical climate; however, put some clean steel in vinegar for days and you'll clearly see corrosion. Thus, I suggest to limit the time in any de-rusting fluid as much as possible. (And, of course, the higher the acid concentration, the shorter the exposure time (with checks/cleaning done more often)!

Quote:
I've used this method on a wide variety of blades, seems to work well on everything I've tried it with, however, a katar might have small gaps where metal meets metal, and it would not be easy to get residual acid out of those gaps. Occasionally I might use a slurry of bi-carb of soda to kill the acid, then thoroughly rinse off the bi-carb.

With vinegar, this is actually an unnecessary step: The beauty of acetic acid is that it is quite volatile - you easily smell it.

Just heat the blade thoroughly, and any residual water as well as acetic acid is gone! A hairdryer is a pretty safe tool - if you're kinda paranoid (which is a good trait for any conservator!), make sure to heat just above the boiling point (i. e. 100°C). This may be easier in a temp-controlled oven - however, arsenic is also volatile...
(Anyway, ventilate well and don't do this in your collection room!)

Regards,

Kai

A. G. Maisey

Kai, as I remarked in the opening post to this thread, I consider this post of yours to be quite valuable, however I would like to comment upon it, and I will do that following this post.

Firstly I am going to give a little bit of my own history that relates to keris, and some blade cleaning instructions that I wrote for distribution to people who were on my mailing list. These instructions were written in about 1992 and at that time these instructions were an accurate reflection of the way in which I cleaned blades. Not only keris blades, but all sorts of blades.

In 1992 I had been collecting keris and other edged weapons for about 37 years. I had begun my collecting with the gift of a small collection at age 12, and I had started adding to that collection a couple of years later. By the age of thirty I had something like 3000 keris and other edged weapons in my collection. My objective way back then was to possess every keris ever made. I knew very little in those days, and I understood even less. But I did have a lot of sharp pointy things. Many were incomplete, many were damaged. Most of them required cleaning and restoration, which I did, and which became a permanent hobby.

In my late twenties I began to learn a little bit more about edged weaponry, most especially about keris, and that massive accumulation of junk that I had put together over 15 years or so was gradually fed into auctions and sold by advertisements in the Saturday morning papers. No EBAY in those days.

In the early 1970's I met the man who was later to become Empu Pauzan Pusposukadgo, I also met another Javanese gentleman who was responsible for the maintenance of the edged weapons held by the Yogyakarta Karaton. I knew him as Romo Murdo. From these men I learnt the basics of the way in which Javanese edged weapons were cleaned and stained.


By the age of about 40 my accumulation of edged weapons had been reduced to no more than 40 keris, two very good wakazashis, one extremely good naginata, and an assortment of other odds and ends.

In 1982 at the age of 41 I was accepted by Empu Suparman of the Karaton Surakarta as his pupil. This was when my understanding of keris began, prior to this I had known almost nothing, well, nothing that had much value in any case.

So by a rough reckoning, I have been playing with keris and other edged weapons for at least 65 years. Prior to 1971, when I was 30 years old, I had cleaned a couple of thousand blades, mostly keris. Some of these I had stained, others I had not. In the 47 years since 1971 I think I've probably cleaned at least ten keris blades every year, as well as a few other blades.

Even when I have a blade stained in Solo, I prefer to clean it myself, because most of the people in Solo who stain blades as a job do not clean the blades properly. They do the bare minimum, and often when a newly stained blade is examined under direct sunlight patches of green or yellow will be seen under the black stain. This is the beginning of new rust. If I find this beginning corrosion the blade goes back to the tukang to do again. Usually in a batch of blades that I have not cleaned myself this return rate is around 20% of the first attempt at stain, and 10% of the second attempt, and there will always be a couple of blades after the second attempt that I will need to clean and stain myself.

So these instructions below are a brief and simple explanation of how I clean keris blades. The vinegar that I mention in these instructions, and that I now use instead of pineapple juice is ordinary white cooking vinegar. According to the manufacturer of the brand I usually use, it has an acetic acid concentration of between 4% and 6%, it costs me about $1 for a bottle. I do not use industrial acetic acid, nor do I use imported Italian balsamic vinegar, just ordinary old white cooking vinegar that I can buy in any supermarket.






To clean a rusty old keris blade:-

Actually any mildly acidic agent will do the job. In Jawa the traditional agent is coconut water, but in recent years people have used other acids such as citric, and very dilute sulphuric.

I prefer pineapple juice, which I can buy in 5 litre tins.

Vinegar works well too.

Scrub the blade with detergent and a hard toothbrush under warm running water, to get rid of any surface dirt and oil. Lay the blade in a trough and cover with the cleaning agent.

A plastic wall paper hanging trough is good for this.

Remove the blade each day and scrub it under running water with a hard tooth brush, to remove the rust that the cleaning agent has freed up.

I usually do this twice a day-morning and evening.

After a few days you will find that most of the rust has washed off, but there will probably be still a few small areas that have little bits of hard rust stuck to them. Carefully chip these pieces of rust off with a sharp tool. A small sharp pocket knife blade, or a saddler's needle works well.

Most blades come clean in under a week, but it could take longer.

My experience with pineapple juice is that longer periods in the soak do the blade no harm at all.

Sometimes during hot weather a culture will grow on top of the pineapple juice, and it will start to smell bad. Ignore this, it does no harm---except maybe to your marriage if you have left the trough in the bathroom.

When all the rust is off, wash the blade thoroughly, and if you do not intend to stain it, kill residual acid with bi-carbonate of soda. Paint on a slurry, leave for a few minutes ,thoroughly rinse off. Pat the blade dry, and then leave in hot sunlight, or use a hairdryer to ensure totally dry.

This completes the cleaning process.

A. G. Maisey

My response to Kai's comments:-

Quote:-
I prefer to work over the blades at least twice daily; I also make sure to thoroughly degrease the blade prior to the acid treatment. If oil shows on the surface, I remove the blade, dry it and degrease again (fittings and crevices can harbor residual oil) - this makes sure that the acid can work on all remaining rust (and, thus, shortening the exposure time).

Agreed, twice daily is better than once daily, and in fact with some blades I will look at them several times during the day if I am able, but for the general run of blades, I usually only rinse off and get rid of freed up rust once a day.
Actually, some deeply corroded blades need to be gone over under magnification and each pit in the blade cleaned mechanically with a needle. I remember one Bali blade that I did like this in order to preserve the original stain. It took me months, half an hour at a time.

The scrubbing part of the process I used to do only with a toothbrush, but these days I use a variety of brushes, depending on the nature of the corrosion, and if necessary I also use steel wool or Scotchbrite pads, or stainless steel pot scrubbers. Probably not a good idea for a beginner to use these more abrasive methods.

Quote:-
This may be true for the keris Jawa culture. OTOH, acetic acid of any notable concentration will eat away iron (and steel even quicker)! If you compare early collected keris from European collections with their "relic" counterparts that have been traditionally "washed" multiple times, I believe it is fair to say that acetic acid (as in coconut "water"/vinegar) does damage keris blades in the long run. The loss of material may be mainly from removing rust which certainly develops quite quickly in a humid tropical climate; however, put some clean steel in vinegar for days and you'll clearly see corrosion. Thus, I suggest to limit the time in any de-rusting fluid as much as possible. (And, of course, the higher the acid concentration, the shorter the exposure time (with checks/cleaning done more often)!

Kai, there is doubt at all that any acid, if the strength is sufficiently great, will eat ferric material, however in my experience fruit juices will have no effect at all up to even months left in the juice, and as for white cooking vinegar, I can say the same up to 3 or 4 weeks.

The erosion noted on old blades is the result of rust that has formed on the blade, the cleaning process has removed the rust and exposed the pitting. The cleaning of anything requires a degree of skill, and cleaning keris blades is no exception. It is not the cleaning process that causes the erosion of the material, it is plain old neglect and the consequent rust.

Your suggestion to put clean steel in vinegar for a few days and note the result indicates to me that your vinegar must be very powerful stuff. The vinegar that I use has no effect on clean ferric material at all, even when the material is left in the vinegar for 2 or 3 weeks.

There is something else that needs to be recognised also:- keris blades and other similar blades only have steel edges, the covering of the blade is iron, or iron + nickelous material. The heat treated steel will certainly react more quickly to both rust causing agents and to acid, this is reason why blade edges sometimes emerge from cleaning in a frayed condition, and the smoothing of these frayed edges is recognised as a part of a cleaning job, but if the rust was not there in the first place, the edges would not have become frayed.


Kai, this last bit of advice that you have given I find both interesting and possibly valuable, my original comment comes first, followed by your comment:-


Quote:

My original comment:-
I've used this method on a wide variety of blades, seems to work well on everything I've tried it with, however, a katar might have small gaps where metal meets metal, and it would not be easy to get residual acid out of those gaps. Occasionally I might use a slurry of bi-carb of soda to kill the acid, then thoroughly rinse off the bi-carb.

Kai's response to my comment:-
With vinegar, this is actually an unnecessary step: The beauty of acetic acid is that it is quite volatile - you easily smell it.

Just heat the blade thoroughly, and any residual water as well as acetic acid is gone! A hairdryer is a pretty safe tool - if you're kinda paranoid (which is a good trait for any conservator!), make sure to heat just above the boiling point (i. e. 100°C). This may be easier in a temp-controlled oven - however, arsenic is also volatile...
(Anyway, ventilate well and don't do this in your collection room!)


The "smell test" might be valid, I don't know, my own sense of smell is not particularly good, and in any case, if I am working with substances that do have a smell I don't notice it after a while. The vinegar that I use has no really noticeable smell at all, certainly none noticeable from a couple of meters away.

What is interesting to me is that heat will get rid of any residual acetic acid.

Why is this so?

I have used vinegar to clean mechanical damascus, and in my experience unless I use a bicarb slurry on the blade prior to the final rinse, there will sometimes be little patches of rust on the blade, bear in mind, this is a smooth polished surface I'm talking about, not a rough surface as with most keris.

Also bear in mind that in my complete cleaning instruction that I posted above, I do recommend heating after drying with a cloth. These days I use a hairdryer, but years ago I often used just direct sunlight for keris, and either an oven with the door open, or a hair dryer for damascus blades. So even after rinse>dry>heat, that rust would sometimes show up, but it never did if I used a bicarb slurry prior to the final rinse.

So my questions Kai are these:-

why does heat remove residual acetic acid?

if heat does remove residual acetic acid, at what level of intensity and duration does this effect begin to occur?

Jean

Just few tips about my personal experience for cleaning rusty or encrusted blades. I am using the same procedure as Alan with generally a very good success and only minor differences:
. I am also using household vinegar but try to buy the 10° (10% vol.) brand which is more concentrated/ effective but still does not react with steel or iron as the H+ concentration (the active agent) is too low (or the PH too high).
. I am using a vertical container made of 2 glued PVC pipes (one small one for housing the blade in the bottom part and a flaring adaptor at the top for housing the sorsoran) which I cover for avoiding the evaporation (hence the dilution) of the acetic acid. I am removing and scrubbing the blade twice a day and carefully scrub it with a steel brush or stainless steel scrubber (with Cif detergent) for removing the softened rust.
From experience I never had to spend more than 36 hours for cleaning a blade, even those covered with black rust since 100 years.
I also tested 10% citric acid and 10% oxalic acid solution (products available in drugstores and also weak organic acids) which have the advantange of not being volatile, but I did not find them more effective.
As Alan says, the cleaning of a blade will expose the pitting which was not visible under the rust but the cleaning process does not cause the pitting.
Regards

Jean

(deleted)

Marcokeris

I normally use citric acid powder (2 teaspoons) added to about 2 liters of water and I leave the blade dipped for a day or two (it depends by the rust) . Then I wash the blade. Then I use sodium bicarbonate with a toothbrush and pass it over the blade. Finally I wash the blade again and dry it with a phone

David

These new-fangled phones these days! LOL!

David

Hey, i seriously don't want to stop this discussion, but please keep in mind that we already have quite a few threads on washing and/or staining keris. I am always interested in new information on this process, but don't think we need to go over the same old ground again and again so please try to be aware of information that we have already discussed in depth before posting. Thanks!

A. G. Maisey

Yes David, I agree, and the old threads cover methods other than acid cleaning.

The major reason I started this new thread is because of two things that Kai mentioned:-

1) that a mild acetic acid can damage steel

2) that there is no need to kill acetic acid residue with bi-carb

Perhaps Kai can give us technical explanations for this, because I have never experienced damage to any blade that I have ever cleaned with vinegar, even though on a couple of occasions I've forgotten I had one soaking, and it got the benefit of 2 or 3 weeks in a vinegar bath.

Similarly, I have seen ferric material react after cleaning with vinegar when I did not use the bicarb slurry before the final rinse. I do not always use bicarb, it is mostly when my experience tells me that I should, or on a return clean when a blade has reacted because I did not use bi-carb the first time.

So now I am waiting for Kai to share his knowledge.

I have only learnt from experience, I have no technical knowledge at all about the things that I use.

But cleaning a blade for the first time might seem like a big thing to somebody new to it, so I believe it is important that those people should get as much guidance as possible.

Rick

I have a (new to me) tombak that I have used Picreator Metal De-corroder on to remove the rust which was pretty substantial.
The result shows a noticeable difference in color between the core and the pamor.
I intend to try a strong, hot coffee solution (in lieu of warangan) to try to make that contrast even more apparent.

I'm hesitant to post pictures here as it is not a keris.

kai

Hello Rick,


Since we're discussing methods in general, I don't think we need to restrict ourselves to keris only. One might even prefer to transfer this thread to the main forum...

Regards,
Kai

kai

Hello Alan,

I apologize for my slow reply - thanks for keeping the ball rolling!



Acetic acid evaporates (as does water) well before reaching the boiling point; this is also the reason why you easily smell vinegar when opening the storage bottle at room temperature. At higher temperatures it evaporates faster. As Jean already mentioned, the boiling point of pure acetic acid is approx. 118°C - if you heat a blade to, say, 120°C for more than a few seconds, you can be sure that all acetic acid is gone (if the working space is well ventilated); vinegar is very diluted acetic acid (about 5%) and behaves closer to water. (This explanation is simplified - let me come up with additional data/info tomorrow.)

I'll try to do some better controlled experiments on the amount of corrosion of steel possibly induced by exposure to diluted acetic acid. This will take a bit longer though - please bear with me...

Regards,
Kai

A. G. Maisey

Thanks Kai, I look forward to your further information.

However, if acetic acid evaporates and leaves no corrosive residue, is the same true of other acids, for example, say, hydrochloric acid?

Does this evaporate and leave no corrosive residue also?

If acetic acid is permitted to evaporate slowly, at a lower temperature, what is the residue that is left?

Paul de Souza

I use lime juice or citric acid as Marco does but it usually leaves a yellow stain on the blade. I don't know how to get rid of it and stays on the blade until it gets the warangan treatment. Any advice?

Sajen

Hello Paul,

like you and Marco I use citric acid for cleaning blades, use hot water and soap to remove the the yellow stain.

Regards,
Detlef

David

Thanks Alan. Yes, i understood your intentions for open this thread. My note was not directed specifically at you, or anyone else for that matter. It was simply a reminder to everyone that there is no need to spend time and space covering aspects of cleaning that we have already discussed in much detail. New information is always welcome.

David

Well Rick, when we started this forum we made a choice to discuss just keris, not all tosan aji. We talked about including tombak at the time and decided not to and i believe that was probably the best decision. That said, however, i believe that in the context of this discussion a few photographs of the cleaning you did on your tombak would not be out of place in this context. It's not the same as presenting the tombak for deeper discussion. I say go for it.

Rick

When I'm finally finished with the rust treatment I'll post the blade before I try an etch with super strong coffee. Right now the blade is in a heavy coating of De-corroder wrapped in plastic wrap to keep it from drying out too quickly.

Something occurred to me about the subject under discussion: there are many variations in quality of steel and pamor material; would this difference not interfere with a consistent result in whatever rust treatment is involved?


/5/20

Well, here are pictures of this blade after treatment with Metal De-corroder (a Renaissance product) a hot rinse and before any etching has been attempted.

It was quite crusty and the color difference was not aparrent; no before pics, sorry.

Attached Images

  

Rick

Bump

jagabuwana

Would be interesting to see your post-etching results, Rick.

Rick

Yes it would; if I had anything that could produce a warangan type of etch.
I'm reasonably happy just to see a contrast between the metals; the EPA doesn't want me to possess arsenic trioxide.

David

Though i do believe you said you were going to try a solution of strong coffee, though perhaps "etch" is not the correct word for such a bath. At least i hope not since i am bathing my stomach in some pretty strong coffee right now. LOL!

Rick

I bought a small jar of instant and made a paste, applied it to the blade and all that happened was an increase in contrast between the pamor and the core.
Not really worth belaboring the board with another tombak picture..

Fernando K

Hello everyone

The only way to remove the oxide is the electrolysis and the zinc-soda method, without attacking the base metal (iron or steel). It is the method used in the museums (besides the ultra-sound) and in the objects recovered from the sea

Affectionately. Fernando

David

Forgive me Fernando, but i become highly skeptical whenever anyone starts a sentence with "the only way to..."
I do see from a search of the "zinc-soda" method that you have been informing these forums of this "only" method since 2011. In fact you seem to be the "only" person to have mentioned it over the years on our forums. However, each time all i can find is a mention of the name and no description of the process. Have you personally used this method? If so, can you describe the steps? Thanks!

A. G. Maisey

David, I believe that from the perspective of the curation of highly valuable objects, that perhaps Fernando is correct in his claim that electrolysis is the only way to remove corrosion on ferric material without in some way affecting the material.

I have had people send me descriptions of how they have used this method, I have had discussions with a couple of museum curators on the pros and cons of using it, and I think that there was a lengthy discussion on its use in this Forum some years ago.

In short, I know about it, but I have never used it, and I doubt that I ever will.

Why would I not use such an apparently excellent method?

Simply because compared with the method I have used for more than 60 years it is too much trouble, and for the type of things I need to clean there is no material advantage.

If I needed to clean a very old, very valuable, very fragile, irreplaceable artifact, I would probably investigate the electrolysis method and consider using it. But for the type I things I need to clean, I consider this state of the art method to be unnecessary.

So I do not use it, for much the same reason that I do not use cabinet maker's tools to replace a paling in a fence:- it is overkill.

David

Understood Alan. Perhaps there is some greater discussion of the process under some other key words than "zinc-soda", but all i found when searching those terms was the brief mention of the process by Fernando with no details attached.
But i do agree that it is probably unnecessary for our purposes and overkill.

A. G. Maisey

I just used the Discussion Forums search facility and put in "electrolysis".

I got more than a few hits.

Here is the first one on my list of hits:-

http://www.vikingsword.com/vb/showt...ht=electrolysis

Might be worth re-reading this thread if you have time. Ann Feuerbach I find interesting.

Fernando K

Hello everyone

On the method of electrolysis, the discussion link has already been uploaded in this forum

On the zinc soda method, the dissolution of caustic soda attacks zinc, forming zinc hydroxide and releasing hydrogen. The hydrogen, in the nascent state, attacks the metal oxide, and the oxygen starts, the dust remains of the original material.

Both have the advantage that they remove the oxide from the "caries" or caverns, which otherwise would have to be eliminated by the treatment of the surface, thus eliminating material.

Any acidic method that is used, such as acetic, while decomposing the oxide, simultaneously attack the non-oxidized metal, or the metallic base, once it has acted on the oxide.