Corroded keris

[A. G. Maisey]

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.

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.

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.

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]

Hello Alan and Ariel,

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! ).

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).

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)!

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