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Author: Subject: Non-reactant material to cool moulten NaOH on
RogueRose
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[*] posted on 16-4-2016 at 13:04
Non-reactant material to cool moulten NaOH on


I've never worked with molten lye before so I'm a little out of my element here and don't know its behavior in this state and temp.

I need some suggestions of a material on which to pour moulten lye onto after it is used as a cleaning dip. I would think that Al would be out of the question and I have a feeling that glass may be as well.

I plan on using a stainless steel pot to heat the lye and I suspect that may be the only readily available material which can withstand hot lye.

I'd like to be able to pour the lye into a thin sheet so it can be broken up later, thick pieces will make for messy and dangerous break-up.

Any suggestions on how to handle this
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DraconicAcid
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[*] posted on 16-4-2016 at 13:16


Teflon, as long as it's not too hot.



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Metacelsus
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[*] posted on 16-4-2016 at 14:14


Copper would also work, and would tolerate higher temperatures. This goes without saying, but use caution when pouring molten NaOH.



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BromicAcid
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[*] posted on 16-4-2016 at 15:04


Quote: Originally posted by DraconicAcid  
Teflon, as long as it's not too hot.


Where did you get this information from? Teflon reacts readily with molten sodium hydroxide, interestingly enough, molten sodium hydroxide is one of the few chemicals often listed as being reactive with PTFE. Not only that but NaOH melts at 318C, whereas teflon starts to break down at 260C (depending on the source) so double-whammy.

@RogueRose: There are some pointers in the sodium thread, nickel is the metal of choice. I personally have had good luck with cast iron (though with slight discoloration). As for stainless and copper I cannot say with any certainty, I had thought that once upon a time I had evaluated using stainless prior to settling on cast iron and had to change my mind due to compatibility but I cannot point to anything concrete.




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DraconicAcid
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[*] posted on 16-4-2016 at 15:45


Quote: Originally posted by BromicAcid  
Quote: Originally posted by DraconicAcid  
Teflon, as long as it's not too hot.


Where did you get this information from? Teflon reacts readily with molten sodium hydroxide, interestingly enough, molten sodium hydroxide is one of the few chemicals often listed as being reactive with PTFE. Not only that but NaOH melts at 318C, whereas teflon starts to break down at 260C (depending on the source) so double-whammy.


A research paper I wrote on using molten salts as solvents many, many years ago. I may very well have misremembered.




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macckone
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[*] posted on 17-4-2016 at 10:32


Nickel is used industrially. Steel should also work. Teflon is definitely a no.
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S.C. Wack
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[*] posted on 17-4-2016 at 10:42


Cast iron is fine but...Nickel foil on ebay!!! Not too expensive...and a cookie sheet...or just the cookie sheet.

[Edited on 17-4-2016 by S.C. Wack]




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j_sum1
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[*] posted on 18-4-2016 at 03:35


Of all the things currently sitting around in my lab, I would probably either try a cast iron dish I have or a graphite slab which I don't think would present any hazards.
What sort of crucible are you using for heating it? Any reason why you wouldn't use the same material?




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Sulaiman
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[*] posted on 18-4-2016 at 05:05


I guess that an oven-dried pre-heated ceramic tile would work well.
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hyfalcon
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[*] posted on 18-4-2016 at 05:34


As long as that tile isn't glazed. Molten NaOH will treat the glaze on ceramic just like glass.

Try a pizza stone.

[Edited on 18-4-2016 by hyfalcon]
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macckone
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[*] posted on 18-4-2016 at 15:47


I would recommend against ceramics. The common ones are alumina silica mixtures readily contaminating sodium hydroxide. Use metal, although aluminum is a poor choice.
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Amos
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[*] posted on 18-4-2016 at 18:40


I will second the suggestion not to use ceramic. Clean a stainless steel surface USING molten sodium hydroxide first and then it should be able to contain it without reacting.



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