Introduction: How to "Salt Out"

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Salting out is a process that can be used to dehydrate Isopropyl alcohol, i.e., separate it from water in an azeotropic solution. Dehydrated Isopropyl is useful as a fuel by itself and in helping to determine the right amount of catalyst to add when making bio-diesel fuel.

Removing water also increases the Isopropyl alcohol's ability to:

> melt ice off your frozen windshield
> dissolve water in gasoline
> burn cleaner when used as a standalone fuel
> provide your pet with an invigorating rub after his next bath, which is curiously strong enough (dry enough) to dislodge stubborn ticks and fleas
> serve as a powerful pet or human wound antiseptic
> wash out those wax filled ears
> save you big $$$ (dough, ka-ching, moola, etc.) think money*

(*99.9% Isopropyl Iso-Heet at auto stores runs around 18.25 cents per ounce. 99.9% Isopropyl made from salting out 50%-91% generic retail brand Isopropyl runs around 6.73 cents per ounce. That is a savings of over 63%. If you use it to dry your gasoline then be sure to remove the residual salt using the addendum method.)

What you need:

- bottle of 50% to 70% Isopropyl alcohol
- a wide mouth glass jar and lid, or other leak and Isopropyl proof container
- a pound of non-iodized table salt
- a turkey baster with a reduced size nozzle
- an empty bottle equal in size to the bottle of Isopropyl alcohol.

Step 1: Start by Adding the Table Salt

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Fill the empty jar about 1/4 full with table salt

Step 2: Add the Hydrated Isopropyl Alcohol

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Fill the jar about 3/4 full with hydrated (50% to 70%) Isopropyl alcohol

Step 3: Shake Contents Vigorously

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Put the lid on the jar, close to seal the contents and shake jar vigorously to be sure the salt and water combine.

Step 4: Let Gravity Separate the Contents

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Place jar on a level surface long enough for the alcohol and salt water to separate (15 to 30 minutes).

Step 5: Keep the Two Layers Separate

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Open jar carefully so as not to remix the two layers.

Step 6: Extract the Isopropyl Alcohol

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Use the turkey baster to extract the top layer, which will be the Isopropyl alcohol.

Step 7: Fill the Receiving Bottle

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Fill a receiving bottle with the turkey baster Isopropyl contents.

Step 8: Label Bottle

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Label the bottle "Dehydrated Isopropyl Alcohol"

Step 9: Use Your Dehydrated Alcohol

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Use in an alcohol stove, lamp, torch, etc. or to give your pet a nice alcohol rub down.

Step 10: Addendum

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You may find that your salted out Isopropyl leaves a salt residue when it is burned. In many applications like a pocket stove the salt residue will continue to serve in the role of helping to separate the Isopropyl and the water when water intrusion occurs from dampness, rain or boil overs.

In other applications the salt residue may not be desired. To separate the salt residue from the Isopropyl use a homemade still. In this case your are not distilling an azeotropic solution of Isopropyl and water but rather separating a liquid from a dissolved solid.

The diagram below illustrates the required components for such a still.


patmccock (author)2009-10-18

i used 91% isoproply alcohol and it wont work why is that?

accuklipper (author)patmccock2017-08-04

I have seen elsewhere on the web that sodium chloride can't concentrate isopropanol past 87%, and the resulting 87% isopropanol is about 2-3% sodium chloride. This seems to be the explanation for the suggestion of magnesium sulfate that is dehydrated by heating. Sodium hydroxide also works, but there is the matter of it being caustic.

DrCoolSanta (author)patmccock2009-10-20

Thats what the product is suppose to be. If you use more dilute alcohol this will work. Just add some water to this and see :P (author)2008-10-29

You could put the salt on your margarita for a scientific buz...or was the alcohol in the water?

CowGuy (author)emergencydpt.com2016-09-28

ISO metabolizes into acetone and you can in fact ingest it though not recommended. Much heavier than ethanol and is dangerously strong, does not cause blindness or instant death but likely to put you close with how strong of an alcohol it is.

Isopropyl alcohol is definitely not something you want to drink. Not all alcohols get you drunk, as far as I know ethanol is the only one that does it without some pretty nasty side effects (although hangovers aren't too fun ;))

I have read that if you drink isopropyl alcohol it can cause blindness or even death.

binnie (author)nathanielg2010-10-16

most alcohols actually cause blindness, and ethanol is really the only alcohol thats safe to drink (not that its that safe eh ;D ) most other alcohols cause blindness in really small quantities, and theyr all very lethal poisons.

lloydrmc (author)2016-02-14

Diagram below?

botronics (author)2012-12-16

Can this work with Vodka? I need pure ethanol for making a Fitzroy Storm Glass. Which is a mixture of camphor, ammonium chloride, potassium nitrate, water and ethanol.

Broom (author)botronics2015-12-12

botronics, think about it. You're asking if it will remove water from the methanol in vodka - so you can mix it with camphor, ammonium chloride, potassium nitrate, and WATER.

botronics (author)Broom2015-12-12

The water content of Vodka is too high for the Fitzroy Weatherglass formula. That why I need to get the water out before mixing it.

Broom (author)botronics2015-12-19

Oh! Thanks. Did not realize that.

yzrider3000 (author)botronics2014-07-28

sounds like a illegal substance lol starts with a m

Broom (author)yzrider30002015-12-12

If you're hinting at "methanol", it's not illegal. If not... you need to put down the bong, because you're not making sense.

fenomen09 (author)yzrider30002015-03-04


simplestatic (author)2008-04-19

Interesting process to know, but seems like a lot of work to get questionable purity IPA. I can currently get 99.99... technical grade isopropyl by the drum for roughly 7 cents an ounce(volume). Just find your local chemical company. They'll sometimes deliver at no extra charge too.

Broom (author)simplestatic2015-12-19

Maybe you should post that as your own instructable...

How to Get 99.99%-Pure Isopropyl Alcohol.

Step 1: Buy it.

You could start your own Instructable channel! Think of the possibilities.

"How to Make a Wedding Ring from Paper Money"

"How to Build a Mercedes Benz at Home, With Just Tens of Thousands of Dollars And a Ride to the Dealership"

"Build Your Own House, Using a Mortgage and a Contractor"

thinkahead (author)simplestatic2008-04-19

I'm guessing but most people would only use 99% Isopropyl for backpack fuel and purity can be asserted with a post-salting out distillation. If you camp every weekend this is no more than a 32 fl oz bottle of fuel per month. A 55 gallon drum contains 7040 fl oz which would last the every weekedn backpacker about 18.3 years and since the price of Isopropyl has increased by 50% in the last year buying a whole drum now might actually pay off down the road. No harm in posting the name of your supplier...

genius245 (author)thinkahead2009-05-31

For a second I thought you said "jetpack fuel" lol

chuckr44 (author)thinkahead2008-08-15

Isopropyl is not a preferred fuel for backpackers because it leaves carbon on the cooking pot. That's why methanol is preferred.

ShawnC35 (author)2015-12-06

Is that not jypsum, instead of lime in drywall normally?

lyfespanj (author)2015-09-13

Purifying Rubbing Alcohol Into 99% Isopropanol

Epsom salt is magnesium sulfate heptahydrate (MgSO4 * 7H20) but can be converted to anhydrous magnesium sulfate (MgSO4) simply by heating the dry crystals at 100 degrees Celsius for two hours. Once in anhydrous form, magnesium sulfate can be added in excess to the rubbing alcohol where it absorbs the water molecules to form various hydrate crystals.

The mixture of isopropanol and hydrate crystals is then poured over a filter; the collected liquid below is roughly 99 percent pure isopronanol.

ricor43 (author)2014-09-30

Is there anything that can be used in place of salt? If not, how can I get the salt out of the alcohol?

cmadsen5 (author)ricor432015-05-03

At the end of thinkahead's instructable (he/she) suggests that if you don't want salt in your isopropyl alcohol, that you should distill it.

Try some cheesecloth.

QiangX (author)2015-04-11

Thanks. Can this method be used to salt out 70% ethyl rubbing alcohol?

dillonxti (author)2015-04-03

thanks worked for me

Che_Surfer (author)2015-02-01

All I can get is the 99% where I live and really want 99.9 to 100. Is it worth it to salt out? I can't stand 99% wish I could just find barrels of the 99.9 reagent here :(

DanC4 (author)2014-12-12

Chemist chiming in. I don't know if anyone else has stated this because there are too many comments for me to look through all of them, so apologies if this statement is redundant.

99.999% IPA is a WORSE disinfectant then 70% IPA. There is a reason why the IPA in the pharmacy is 70% IPA and 30% water and that is because the water actually improves the efficacy of the product as a disinfectant. Alcohols as disinfectants are most effective in the 60-90% range, above or below that and they become less efficient at denaturing the microbe's proteins.

Also, please note that while alcohols are broad disinfectants and can kill a lot of different bacteria and fungi as well as deactivating viruses, they aren't as effective as say bleach or peroxides for killing dormant cells or spores that are designed to weather harsh conditions. So if something needs to be 100% for sure clean (for example, surgical equipment or for people with compromised immune systems), it's best to use a harsher product.

That being said, IPA is an excellent, topically safe (i.e. it's safe to touch, not to drink) product that does a really good job at making surfaces microbe free for most conventional purposes. Also it evaporates away after using it, is less damaging to surfaces and doesn't leave behind a bleach smell. Score!

Pbyrd (author)2014-04-16

This is probably a rather ignorant question, but I'm assuming any sort of non-iodized salt would suffice? I have non-iodized sea salt, so I'm assuming this would work fine, but I wanted to make absolutely sure.

J@50n (author)2009-09-27

just wondering, is this the same as denatured alcohol?

alhewy (author)J@50n2014-04-05

No, "Isopropyl Alcohol" is the working name for the chemical compound 2-propanol (C3H7OH) usually mixed with water to about a 70% purity. "Denatured alcohol" is the working name for ethanol (C2H5OH) that's got nasty additives in it. They add impurities to deter people from drinking it... but I guess some hobos will always go for the cut-price booze, even to their own poor health :)

JAMdown (author)2014-02-19

Why you insulting him? He is answering someone's question and giving a good practical answer.

dmars (author)2014-01-22

Does anyone know a good way (cheap, not too involved manual labor) to get the salt out of the alcohol? I'm using it in an antique alcohol lamp, one that has a longish chimney, and the salt comes up the wick in rather huge quantities. It's a pretty orange while it's burning, but after it completely burns there's a solid crust on the end of my wick and the flame goes out. I have to trim the wick and relight it about every 15 minutes. Salted out IPA (isopropyl alcohol) with the salt somehow gone would be perfect!

DrSimons (author)2013-09-30

Nice instructions, I'll try adding more salt (had tried this previously with mixed results, but I didn't use nearly as much salt). One thing: BE CAREFUL if you decide to distill anhydrous IPA, let alone fuel, as hinted in the intro. If you are gonna do that, make sure you use a hot plate or other electric heat source, i.e no open flame. Probably don't even try it with gasoline, unless you want to read about yourself on the local news (as a ghost).

AlwaysChoseCharmander (author)2012-08-14

Just tried this, stove works much better thanks! I put the Isopropyl in the same container. Crossed out the fifty percent and wrote 'much higher'.

ironLes4 (author)2012-08-05

can you use a salt subtitute

h0meIandsecurity (author)2010-11-07

hahahaha, funny

junits15 (author)2009-09-03

what happens if I use iodized salt?

Mikie-z (author)junits152010-05-20

Most likely reason why people say to not use iodized salt is because it has iodine which can either A) make I2 which is non polar and may mix with alcohol as apposed to the water or B) could make a iodo-*suffix* compound.
Only speculation from a hobby chemist though.

Qcks (author)2010-02-07

Just gonna add...
If you're having issues with salt residue in your isopropyl, you can limit the solubility of the Sodium Chloride by doping the isopropyl with sodium hydroxide prior to salting it.

This has the advantage of having a solvation effect with the salt and the base (Sodium Hydroxide competes with Sodium Chloride for solvation with the water because both have a sodium cation). Any residual hydroxide compound should burn clean.

The biggest downside is that you might begin to push your isopropyl to undergo a synthesis reaction, but due to it's shape that's not very likely (that is to say, it's stearically hindered, and thus, unlikely to undergo any synthesis reactions).

spark master (author)2009-10-06

Methyl and isopropal can be absorbed through the skin, if you use it a lot it can have bad effects on you, rub downs with alks should only be with ethyl. They tell you now never rub your kid down with it . When I was a kid everyone knew to use rubbing alks for fevers. No Mas muchacha

spark master (author)2009-10-06

isopropal is lousey for alcohol stoves, methyl is great , but ethyl is best (more btu's. Since we can drink it it is heavily taxed. Denatured alks are mixtures and can have ethyle and methyl and other crap. The other crap will soot pans and in some cases stinks like heck. Go to the site for S-L-X denatured alcohol, the stuff varies. GO to Minibull and look for Tinny's fuel comparasons, it explains much. This is a great article/instructable. You could if you had equipment, or really cold cold streak, do cryogenic distillation. Put a few gallons in a drum freeze it to -20 for say a few days then let it 'warm to -10 few hours, then refreeze to -20, do this a few cycles and ice crytals will form on out sideof alcohol column. Well it does with hard apple cider. But you need those frigid upstate NY death by cold winters. Farmers could leave casks of hard cider freeze then pop a hole in the center and drain off the liquer. Not worth the effort though. Buy heet or Air Brake Antifreeze, pure methyl spirits, 98%. If you are lucky enough you may find a speed shop that sells it by the gallon out of a drum, (bring clean jug/can) 4-8 bucks a gallon. Sadly I can't find one by me. I enjoyed this piece I will re read later on in the week.

Pyrotechnic-Robot (author)2009-08-12

slurp slurp bubble bubble gurgle gurgle haha very nice.

Berkin (author)2009-06-09

What happens if you use iodized salt?

lilpepsikraker (author)Berkin2009-08-07


Berkin (author)lilpepsikraker2009-08-12

I doubt that.

chuckr44 (author)2008-03-10

I'd be interested if you used a beer-making specific gravity meter for alcohol, to measure the SG of the alcohol your produced. Is it closer to 90%? Is this method efficient? Thanks for a great instructable.

thinkahead (author)chuckr442008-03-15

You are welcome and thanks for the compliment. Just as I was getting ready to build a hydrometer it dawned on me that all I really need to do is to measure volume and weight. I have a good postal scale and volume is also pretty easy to measure with just kitchen wear. All measurements so far confirm 99-100% Isopropyl.

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