# burrning alcohol
**URL:** https://boards.straightdope.com/t/burrning-alcohol/223396
**Category:** Factual Questions
**Created:** [January 8, 2004, 11:18am UTC](https://boards.straightdope.com/t/burrning-alcohol/223396 "2004-01-08T11:18:50Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@OM\_Waterfall](https://boards.straightdope.com/u/OM_Waterfall)
#### Post date: [January 8, 2004, 11:18am UTC](https://boards.straightdope.com/t/burrning-alcohol/223396/1 "2004-01-08T11:18:50Z")
hi to all. after the now infamous brandy on christmas pudding episode of christmas (NEVER AGAIN!!), I was wondering what the required % of alcohol to burn is- is there some scientific way to figure it out? also is it alright if I spell alcohol alchohol?
SIZE=1]I swear I saw it spelt like that all the time, hmm smells like a conspiracy…[/SIZE]
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### Author:  [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)
#### Post date: [January 8, 2004, 11:28am UTC](https://boards.straightdope.com/t/burrning-alcohol/223396/2 "2004-01-08T11:28:22Z")
Did you warm it first?
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### Author:  [@antechinus](https://boards.straightdope.com/u/antechinus)
#### Post date: [January 8, 2004, 12:13pm UTC](https://boards.straightdope.com/t/burrning-alcohol/223396/3 "2004-01-08T12:13:18Z")
You are interested in **flash point** versus concentration of ethanol in water solution.
Flash point is the temperature at which a ignition source 1cm from the liquid will cause ignition.
As the conc. of EtOH in water increases the flash point decreases. At low concs of EtOH you need to heat it up a bit to get enough EtOH vapour to maintain combustion.
100% ethanol ~13C
80% ethanol/water ~24C
70% ethanol/water ~29C
You can find this relationship empirically, but do a google you might find a nice plotted relationship.
IIRC proof of spirits was determined in days of old by wetting gunpowder with the spirit. If it did not ignit it was not proof. 100% proof is 57% alcohol.