# Dangers to boiling to rubbing alcohol? **URL:** \ **Category:** Factual Questions\ **Created:** [November 5, 2004, 2:44am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117 "2004-11-05T02:44:00Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![saluki\_fan](https://avatars.discourse-cdn.com/v4/letter/s/b2d939/32.png) [@saluki\_fan](https://boards.straightdope.com/u/saluki_fan)\ **Post date:** [November 5, 2004, 2:44am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/1 "2004-11-05T02:44:00Z")
If I wanted to sterilize and clean some equipment out in my garage, would placing the parts in a pan of boiling rubbing alcohol be a safe way to clean them? The reason I want to use rubbing alcohol is I know that the alcohol will disolve the grime and gunk the fastest and most efficient way possible. Thanks. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [November 5, 2004, 2:48am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/2 "2004-11-05T02:48:28Z")
Boiling any flammable or combustible liquid in anything but a highly controlled situation is asking for an explosion, fire or both. There are many perfectly safe cleaners and degreasers on the market that can be used at room temperature. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 5, 2004, 3:28am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/3 "2004-11-05T03:28:05Z")
Having boiled a mixture of acetone and perchloric acid on my gas stove, many years ago, without killing myself, I agree with **danceswithcats**. Boiling isopropanol is bad news, unless you know what you are doing, and take suitable precautions. -In case anyone wants to know, the acetone turned into a nice 3" X 1’ carbon snake, without igniting. It _should_ have exploded. ---
**Author:** ![Roches](https://avatars.discourse-cdn.com/v4/letter/r/bc8723/32.png) [@Roches](https://boards.straightdope.com/u/Roches)\ **Post date:** [November 5, 2004, 3:32am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/4 "2004-11-05T03:32:17Z")
The flashpoint of rubbing alcohol (70% isopropanol in water) is 25°C (77°F), so the vapor from boiling rubbing alcohol could catch fire (or even explode in a confined space with a lot of vapor) if exposed to an open flame or spark. Isopropanol vapor is about twice as heavy as air, so there’s a high risk that the vapor could settle to your heat source and catch fire, especially if you use an open flame. The reason why boiling water is effective at killing bacteria is that it’s hot (100°C, 212°F). The boiling point of rubbing alcohol is a bit lower than water (87°C, 189°F), so it would be slightly less effective than water as a disinfectant even if you could boil it safely. I’d recommend using a degreaser at room temperature, then using a disinfectant. You may want to rinse the parts in clean tap water or (preferably) distilled water to remove disinfectant residue. ---
**Author:** ![postcards](https://avatars.discourse-cdn.com/v4/letter/p/8e8cbc/32.png) [@postcards](https://boards.straightdope.com/u/postcards)\ **Post date:** [November 5, 2004, 4:01am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/5 "2004-11-05T04:01:56Z")
The alcohol should dissolve the gunk and sterilize your equipment **without** having to be boiled. Whatever gave you the idea that boiling alcohol would be a solution? (No pun intended…) ---
**Author:** ![saluki\_fan](https://avatars.discourse-cdn.com/v4/letter/s/b2d939/32.png) [@saluki\_fan](https://boards.straightdope.com/u/saluki_fan)\ **Post date:** [November 5, 2004, 4:06am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/6 "2004-11-05T04:06:01Z")
> [@postcards](#): > > Whatever gave you the idea that boiling alcohol would be a solution? (No pun intended…) Just a thought that if rubbing alcohol at room temperature helped get rid of the gunk, then boiling hot rubbing alcohol must really loosen it and clean it. I really have some dumb ideas anymore :smack: ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [November 5, 2004, 4:34am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/7 "2004-11-05T04:34:04Z")
> [@saluki\_fan](#): > > If I wanted to sterilize and clean some equipment out in my garage, would placing the parts in a pan of boiling rubbing alcohol be a safe way to clean them? The reason I want to use rubbing alcohol is I know that the alcohol will disolve the grime and gunk the fastest and most efficient way possible. Thanks. It is safe to boil rubbing alcohol as long as you don’t use anything involving sparks or open flames. An electric hot plate or sand bath is fine. I’ve done it dozens of times in the lab. If you have really greasy gunk, a gasoline soak at room temperature would do a better job than alcohol. I’d have to know more about the nature of the gunk to say what would be best. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [November 5, 2004, 4:58am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/8 "2004-11-05T04:58:25Z")
Plus, remember that hot alcohol is going to evaporate a LOT faster than water at the same temperature. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [November 5, 2004, 5:10am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/9 "2004-11-05T05:10:17Z")
Why don’t you just let them soak longer. Let them sit a while, shake up, repeat. The take an alcohol soaked brush or hard sponge to it. If you feel you must boil, perhaps a crockpot with a decent temperature control? ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [November 5, 2004, 5:13am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/10 "2004-11-05T05:13:59Z")
Guess it’s obvious but correction: “Then” take an alcohol soaked… ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [November 5, 2004, 6:07am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/11 "2004-11-05T06:07:13Z")
> [@NattoGuy](#): > > If you have really greasy gunk, a gasoline soak at room temperature would do a better job than alcohol. I’d have to know more about the nature of the gunk to say what would be best. This is a bad idea for two reasons. First off gas leaves a greasy residue, so it is not going to leave the item clean. Secondly, gas is very explosive if and when the mixture gets in the flamable range. Heating gas on a stove (like the OP mentioned) would be a major league dumb idea. People have died from using gas as a solvent. ---
**Author:** ![Chairman\_Pow](https://avatars.discourse-cdn.com/v4/letter/c/838e76/32.png) [@Chairman\_Pow](https://boards.straightdope.com/u/Chairman_Pow)\ **Post date:** [November 5, 2004, 6:28am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/12 "2004-11-05T06:28:13Z")
> [@Roches](#): > > The flashpoint of rubbing alcohol (70% isopropanol in water) is 25°C (77°F), so the vapor from boiling rubbing alcohol could catch fire (or even explode in a confined space with a lot of vapor) if exposed to an open flame or spark. Isopropanol vapor is about twice as heavy as air, so there’s a high risk that the vapor could settle to your heat source and catch fire, especially if you use an open flame. Please explain this to me. I’m positive that I’ve used rubbing alcohol when it’s been like 90 and not died. How does an ambient temperature of 77\* not set it off but a spark at 77\* would? Can a flaming piece of something be at that temperature? ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [November 5, 2004, 6:47am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/13 "2004-11-05T06:47:52Z")
Flashpoint is the lowest temperature at which the vapor of a combustible liquid can be made to ignite momentarily in air. Note it says can be made to ignite, not will for sure ignite. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [November 5, 2004, 6:48am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/14 "2004-11-05T06:48:25Z")
Flashpoint does NOT mean the temperature at which a substance will spontaneously erupt in a fireball. It is the temperature at which a substance emits vapor in large enough concentrations that they could be ignited by a spark or a flame. When you boil rubbing alcohol, you are exceeding its flashpoint, but that’s perfectly safe as long as there is no spark or flame in the area. Use an appropriate heat source and adequate ventilation and you’ll be fine. In fact there’s a high-school chemistry experiment from antiquity in which they boil leaves in alcohol to extract the chlorophyll. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [November 5, 2004, 8:04am UTC](https://boards.straightdope.com/t/dangers-to-boiling-to-rubbing-alcohol/273117/15 "2004-11-05T08:04:10Z")
That was why I put the “highly controlled situation” qualifier in my post. 😉 I have lots of stories after years as a firefighter, hazmat tech, and paramedic that are filed under :smack: