au bain marie heating, max. alcohol temperature

gido

Well-known member
May 31, 2008
i am in the process of dissolving (or rather, trying to) some mimosa abs in alcohol. the mimosa won't melt with lower temperatures like 50 degrees celsius, which is what i have considered safe and used so far. i have read that the boiling point of alcohol is 75 degrees celsius, and bringing alcohol up to it's boiling point does not seem like a good idea, if you don't know what will happen, like me.

so, the question is: what is the maximum safe temperature to use?
 

merry.waters

Well-known member
Jan 13, 2010
i am in the process of dissolving (or rather, trying to) some mimosa abs in alcohol. the mimosa won't melt with lower temperatures like 50 degrees celsius, which is what i have considered safe and used so far. i have read that the boiling point of alcohol is 75 degrees celsius, and bringing alcohol up to it's boiling point does not seem like a good idea, if you don't know what will happen, like me.

so, the question is: what is the maximum safe temperature to use?

Boiling isn't different from water. As ever it depends where the source of heat is etc. So don't do that in a micro wave oven!

Dissolving the absolue in alc should be possible with much a lower temperature than at the melting point. Take some abs apart, may be on aluminium foil. Drop that into the alc. If the abs doesn't vanish within a reasonable time, You could accelerate the process by heating it bit by bit in a water bath while watching it carefully - as not to spill the precious material. Take Your time,

Good Luck!

To get used to the process - recommended - You could test Your personal technique with dissolving loads of salt in water or the like.
 

gido

Well-known member
May 31, 2008
merry.waters,

Boiling isn't different from water. As ever it depends where the source of heat is etc. So don't do that in a micro wave oven!

boiling point of alcohol is 78.4 °C to be exact.
and of course i will not use a microwave. that wouldn't be heating au bain marie.

i am just wondering up to what temperature i can keep the water, because alcohol has a lower boiling point than water. and i don't know, but i suspect boiling alcohol might be dangerous.

Take Your time

that's probably good advice. but alas, i am not very patient. probably next time. for now, i can't wait to start playing around with it.
that it, unless it would really compromise the quality the resulting dilution. in that case i wouldn't really have a choice.
 

merry.waters

Well-known member
Jan 13, 2010
merry.waters,



boiling point of alcohol is 78.4 °C to be exact.
and of course i will not use a microwave. that wouldn't be heating au bain marie.

i am just wondering up to what temperature i can keep the water, because alcohol has a lower boiling point than water. and i don't know, but i suspect boiling alcohol might be dangerous.



that's probably good advice. but alas, i am not very patient. probably next time. for now, i can't wait to start playing around with it.
that it, unless it would really compromise the quality the resulting dilution. in that case i wouldn't really have a choice.

The boiling point depends on air pressure too, on impurities etc. At 60°C it won't boil.

ps: with technical processes the worst to happen is to have no choice left. There should always be a second option, in case the first doesn't work for what so ever. Take care.
 
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gido

Well-known member
May 31, 2008
merry.waters,

The boiling point depends on air pressure too, on impurities etc.

well, i guess the main impurity is water. ;)
but the alcohol is heated in a small, full, rather tight closed glass 10ml bottle. i presume that would be a good condition to build up pressure, doesn't that take the boiling point higher?

At 60°C it won't boil.

ok.
what would happen if it did get to a boil, could it explode? what are the dangers.

ps: with technical processes the worst to happen is to have no choice left. There should always be a second option, in case the first doesn't work for what so ever. Take care.

thanks for the input.
 
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merry.waters

Well-known member
Jan 13, 2010
merry.waters,



well, i guess the main impurity is water. ;)
but the alcohol is heated in a small, full, rather tight closed glass 10ml bottle. i presume that would be a good condition to build up pressure, doesn't that take the boiling point higher?



ok.
what would happen if it did get to a boil, could it explode? what are the dangers.



thanks for the input.

Haaaalooo! Stop that.

Don't ever heat a volatile fluid in a closed container.

It could explode. Man, I was a 8 yo kid when I did exactly that, with rose water in a sealed glass vial over a candle. For sure it exploded. My face was all covered with rose scented blood. My mother was shocked to death - nearly. I kept my eyes, lucky guy!

Gido, I have to suggest You catch Yourself a friend who is more of a tech guy. Please, if not available, try it without heating first. Fill the container max to the half so You could stir the stuff inside. Test Your methods with less precious or harmful substances. Alas, I can't help You any further from the distance.
 

gido

Well-known member
May 31, 2008
the initial part, going from room temperature to 50c, i do that with the lid loosened. i have checked it by opening now en then the first time, when there's pressure you will hear/feel it. i was thinking that, as soon as a stable temperature is reached, tightening the cap won't be a problem. the temperature might fluctuate 5 degrees celsius max. am i wrong, is this still dangerous?

and if i am: if you can't put a lid on at all, the alcohol will simply evaporate. how else are you going to do it?

btw. most of the mimosa is dissolved by now. i will take the heat down overnight, it will probably be done tomorrow anyway. :)
 
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gido

Well-known member
May 31, 2008
but could my method be still dangerous when the temperature is more or less continuously stable? personally i don't see why it should explode when the temperature doesn't get too high, or am i right that only the heating up and cooling down parts poses a risk. (i ask because i am not sure now)
 

merry.waters

Well-known member
Jan 13, 2010
but could my method be still dangerous when the temperature is more or less continuously stable? personally i don't see why it should explode when the temperature doesn't get too high, or am i right that only the heating up and cooling down parts poses a risk. (i ask because i am not sure now)

Gido, I have ... sent You a PM.
 
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janmeut

Well-known member
Aug 11, 2006
When you heat alcohol, first make sure there is no open fire. That includes a pilot light in for instance your water heater system or central heating system. Ventilate well. Don't overheat. Use plastic film or metal foil to close a heated container, so that pressure is easily released if necessary. Keep the heated liquid in sight all the time. Remind that even with all precautions mentioned it is still dangerous.

Remind that on cooling down the absolute might crystalise again...
 

merry.waters

Well-known member
Jan 13, 2010
Don't overheat.
...
Remind that on cooling down the absolute might crystalise again...

Aren't there any other solvents that are usable without heating? DiPropylenGlycol (DPG) for instance. As You've written, if temp goes down the solution will probably decompose again. Heat does only accelerate the process of dilution. An other method is to simply stir the liquid twice in a while and wait its time, isn't it?
 

gido

Well-known member
May 31, 2008
jan, have you tried dpg with mimosa? the 25% dilution in alcohol didn't work, some bits do not dissolve. i can add more alcohol or dpg, i'm thinking about 12,5%. what would be the best option?
 

janmeut

Well-known member
Aug 11, 2006
Mimosa absolute is a horror. It is hard to solve in alcohol and DPG. I think therefor TEC is not an option either, a more apolar solvent like DEP might work, did not try that so far.
 

David Ruskin

Well-known member
May 28, 2009
If your Mimosa absolute won't dissolve in absolute alcohol then it isn't Mimosa absolute (the clue is in the name). Concerning alcohol, it is not the boiling point you need to know, it is the flash point which is 13-14 deg C and the autoignition temperature which is 363 deg C.
 
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gecko214

Well-known member
May 7, 2010
I had a terrible time with mimosa abs also. Even with heating as you are doing. Just no using it. Finally used IPM, which is in turn solvable in alcohol. I keep the dilution of mimosa at 33% in the IPM and it is usable/pourable. So far the IPM has been great for everything I need to dilute. the exception, strangely, was oakmoss abs, which would not dilute in IPM.
 

ECaruthers

Well-known member
Feb 8, 2009
Let me repeat merry.waters caution against heating in a closed container. Wikipedia has a graph of ethyl alcohol's vapor pressure vs. temperature. Between 50 C and 100 C the pressure goes up about 10 fold. That is, it's about 1/3 of the surrounding atmospheric pressure at 50 C and almost 3 times atmospheric pressure at 100 C. Unless you're buying your glasswear from a chemical supply company it's not possible to know in advance whether it can stand this much pressure without exploding.
 

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