Coffee Stains

rasdan · 7th June 2011, 04:19 PM

Thanks for the pointers Kai.

I think Alan's explanation would cover wootz as well.

I am considering a few options now. Unfortunately I don't have sample blades of same origin. I am thinking of brushing a bit of citric acid on the blade to start with, but I'm not sure. I guess I'll browse and read a bit more on this area on the net. Thanks again

mrwizard · 7th June 2011, 04:50 PM

Hello Rasdan,

I don't have any wootz blades but i have frequently read that Nital is recommended for etching them. Nital is a mixture of ethanol and nitric acid. You can buy it at chemical suppliers. Don't *ever* try to mix it yoursself, if the concentration of the nitric acid gets to high it tends to explode!

Best Regards,
Thilo

rasdan · 7th June 2011, 06:17 PM

Hi Thilo,

Kaboom!! No, don't want that to happen. Thanks for the advice. It's like you can tell I'm into experimenting things.

Actually these chemical stuff is pretty hard to get here in Malaysia. There's a nutcase around KL recently goes around splashing people with acid for no reason. He is still at large. So, at the present time, I think if I try to buy any acid without proper papers, I'm certain people would give me a frighten look and dial 911.

A. G. Maisey · 17th June 2011, 07:55 AM

Rasdan I have had a conversation with a friend who is somewhat of an expert on wootz.

His advice for etching is NOT to touch ferric chloride, he claims that the chloride can damage the steel in the long term --- first time I've heard this, but apparently wootz fanatics believe it to be so.

His recommendation for etching is a 5% nital solution applied with a cotton swab for a brief period of time, starting at 10 seconds and working up.

Rinse off, kill the nital with a slurry of bicarb of soda, rinse, dry, oil.

He did comment that it would be best if the blade could be demounted and immersed fully in the solution, but he recognises that this is not always possible.

mrwizard · 17th June 2011, 09:04 AM

Be careful with the cotton swab afterwards.
Cotton and nitric acid is a fun combination

A. G. Maisey · 17th June 2011, 09:49 AM

I'm no chemist Mr. Wizard, and in this matter I will bow to your superior knowledge if I happen to be incorrect, but my memory of the process for manufacture of gun cotton is that for the combination of cellulose and nitric acid to take place, the nitric acid needs to be free to combine, so it is mixed with sulphuric acid. If the nitric acid is in combination with the ethanol of the nitral, surely it is not free to combine with the cellulose of the cotton?

Is this correct , or am I way off track?

mrwizard · 17th June 2011, 11:11 AM

Hello Alan,

You are correct if you want to set up a controlled process to manufacture nitrocellulose (gun cotton) which is relatively stable.
Just combining cotton and nitric acid by itself, may lead to a highy unstable explosive material (xyloïdine).
see page 245 and following in T.L. Davis "The Chemistry of Powder and Explosives" http://www.scribd.com/fullscreen/559...w1m9v49ztfc2bu

If or if not that happens depends on many process parameters (e.g. temperature, concentration, luck). Ditching a cotton rag in nital and then letting it dry is in my opinion like tossing some dice. IMHO the rag should at least be extensively watered before it begins to dry.

Nital by itself is a dangerous substance:
http://www.ab.ust.hk/hseo/tips/ls/ls005.htm

Even some on first sight harmless substance like lineseed oil may become dangerous if the safety protocols are not followed: http://www.naturalhandyman.com/iip/i...uscombust.html

Best Regards,
Thilo

17th June 2011, 11:11 AM	#7
mrwizard Member Join Date: May 2010 Location: Dortmund, Germany Posts: 102	Hello Alan, You are correct if you want to set up a controlled process to manufacture nitrocellulose (gun cotton) which is relatively stable. Just combining cotton and nitric acid by itself, may lead to a highy unstable explosive material (xyloïdine). see page 245 and following in T.L. Davis "The Chemistry of Powder and Explosives" http://www.scribd.com/fullscreen/559...w1m9v49ztfc2bu If or if not that happens depends on many process parameters (e.g. temperature, concentration, luck). Ditching a cotton rag in nital and then letting it dry is in my opinion like tossing some dice. IMHO the rag should at least be extensively watered before it begins to dry. Nital by itself is a dangerous substance: http://www.ab.ust.hk/hseo/tips/ls/ls005.htm Even some on first sight harmless substance like lineseed oil may become dangerous if the safety protocols are not followed: http://www.naturalhandyman.com/iip/i...uscombust.html Best Regards, Thilo Last edited by mrwizard; 17th June 2011 at 11:27 AM. Reason: added reference

7th June 2011, 04:19 PM	#1
rasdan Member Join Date: Dec 2004 Location: Kuala Lumpur Posts: 369	Thanks for the pointers Kai. I think Alan's explanation would cover wootz as well. I am considering a few options now. Unfortunately I don't have sample blades of same origin. I am thinking of brushing a bit of citric acid on the blade to start with, but I'm not sure. I guess I'll browse and read a bit more on this area on the net. Thanks again

7th June 2011, 04:50 PM	#2
mrwizard Member Join Date: May 2010 Location: Dortmund, Germany Posts: 102	Hello Rasdan, I don't have any wootz blades but i have frequently read that Nital is recommended for etching them. Nital is a mixture of ethanol and nitric acid. You can buy it at chemical suppliers. Don't ever try to mix it yoursself, if the concentration of the nitric acid gets to high it tends to explode! Best Regards, Thilo

7th June 2011, 06:17 PM	#3
rasdan Member Join Date: Dec 2004 Location: Kuala Lumpur Posts: 369	Hi Thilo, Kaboom!! No, don't want that to happen. Thanks for the advice. It's like you can tell I'm into experimenting things. Actually these chemical stuff is pretty hard to get here in Malaysia. There's a nutcase around KL recently goes around splashing people with acid for no reason. He is still at large. So, at the present time, I think if I try to buy any acid without proper papers, I'm certain people would give me a frighten look and dial 911.

17th June 2011, 07:55 AM	#4
A. G. Maisey Member Join Date: May 2006 Posts: 7,015	Rasdan I have had a conversation with a friend who is somewhat of an expert on wootz. His advice for etching is NOT to touch ferric chloride, he claims that the chloride can damage the steel in the long term --- first time I've heard this, but apparently wootz fanatics believe it to be so. His recommendation for etching is a 5% nital solution applied with a cotton swab for a brief period of time, starting at 10 seconds and working up. Rinse off, kill the nital with a slurry of bicarb of soda, rinse, dry, oil. He did comment that it would be best if the blade could be demounted and immersed fully in the solution, but he recognises that this is not always possible.

17th June 2011, 09:04 AM	#5
mrwizard Member Join Date: May 2010 Location: Dortmund, Germany Posts: 102	Be careful with the cotton swab afterwards. Cotton and nitric acid is a fun combination

17th June 2011, 09:49 AM	#6
A. G. Maisey Member Join Date: May 2006 Posts: 7,015	I'm no chemist Mr. Wizard, and in this matter I will bow to your superior knowledge if I happen to be incorrect, but my memory of the process for manufacture of gun cotton is that for the combination of cellulose and nitric acid to take place, the nitric acid needs to be free to combine, so it is mixed with sulphuric acid. If the nitric acid is in combination with the ethanol of the nitral, surely it is not free to combine with the cellulose of the cotton? Is this correct , or am I way off track?