Can anyone help me please.
I have had caustic in Meth. for almost twenty four hours now and when I shake it, it resembles one of those "snowfall at Christmas domes" and I am not sure if I am able to use it.
It has been shaken repeatedly but still has a deposit on the bottom of the jar.
I am ready to commence a batch with the oil heated up and would appreciate a quick reply if at all possible.
Thanks.

Is it cold down your way. That will affect it.

You WILL need to dissolve it befor using it. Try crushing and constant mixing. Remember for future use KOH will always dissolve better.

Joe

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sounds like your adding methanol to pearl. I mix this up by the bucket load each day in the wine industry and find that it will fuse itself togethor if adding liquid to pearl caustic. Then it sets like a brick, making it impossible to break down. My advice is to add the pearl to mixing methanol "slowly" and you shouldnt have a problem. No answers for your current situation

As per your PM, My reply is the same, with a little difference:
There are 3 possibilities:
1. There is so much caustic that it saturated the methanol - unlikely in the proportions you should be using.
2. The caustic is degraded by exposure to air - absorbs CO2 from the air and forms Sodium Carbonate which is insoluble in methanol.
3. Your mixing has been inadequate.

I vote for 2 - degraded caustic.


If the amount which did not dissolve is a small portion of what was added, then you could add about the same or a little more, to make up for what didn't dissolve.
Take a 200mL portion and react a 1 litre sample of your oil to determine if there is enough caustic to react the oil.

If the sample does not work, or fails the 3/27 test, add more caustic to the methanol and try again.
When you have the right amount of caustic, use it to react the remaining oil in your batch.

I hope this helps
Tony.

Hi Drover,

Sorry to hear that your NaOH won't dissolve - I have had a similar problem, but perhaps not quite as bad. I have tried brand new containers of finely ground 99.9% caustic soda (not pellets) and never had it completely dissolve. There has always been at least a very small amount of undissolved particles.

I have searched around for info on this subject and generally people seem to suggest switching to KOH, and I probably will one day but don't want to give up on NaOH yet - maybe only because I want to use up my container of NaOH. The last couple of batches I mixed the NaOH and methanol for an extended period of time, made sure it was kept warm enough and eventually went ahead and used it (I mean the upper solution after letting any undissolved particles settle, leaving only a few mLs unused).

It has worked alright for me doing this but I do wonder what the undissolved particles could be. If it is insoluble sodium carbonate as Tony suggests then maybe a small amount doesn't matter. I wonder if some supplies of caustic soda just have a small amount of sodium carbonate as purchased and that's what I'm seeing. I have wondered whether this is partly why they don't seem to say 100% NaOH: there are traces of stuff like maybe KOH and sodium carbonate?

Anyway, hope you were successful with your batch. Did you get the caustic to dissolve or put the batch on hold?

Cheers, Paul

KOH dissolves in methanol in seconds with only minor agitation.

Problem solved.

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Sean

I use NAOH and it does clump up but I use something to crush it up like a big stick or a stainless steel potato masher and it starts to disolve then. I normally mix well and add really really slow.

Hello Drover

What brand of caustic are you using and is it NaOH or KOH? What does the container say?
What brand of methanol are you using and what does the container say?
Estimate how much of the original amount of Caustic has disolved.

G'day Tilly,
The caustic I am using is NaOH and it is branded "Mechanix Caustic Soda". It is distributed by Pascoe's of Welshpool in Western Australia but I note it is made in China.
The Methanol was purchased in in a 200 litre drum from an agent of Coogee Chemicals who informed me all the methanol in Australia comes from a manufacturing facility in Melbourne (could have been Sydney) I have since tried another batch and had similar problems with the caustic dissolving and I have come to the conclusion there is something wrong with it.
I would be interested in your opinion.
Thanks.
Drover.

Hello Drover

According to This MSDS Mechanix Caustic Soda is >98% purity so that should be fine.
Coogee Chemicals is correct, there is only one manufacturer of methanol in Australia. Make sure it does not say methylated spirits because that will not work.

Bottom line, it should disolve. Make sure you keep stiring it because in my experience if you leave it sit the NaOH will form into a solid lump similar to concrete on the bottom of the container. Has it done that?