How to "Salt Out"




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

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

Step 2: Add the Hydrated Isopropyl Alcohol

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

Step 3: Shake Contents Vigorously

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

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

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

Step 6: Extract the Isopropyl Alcohol

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

Step 7: Fill the Receiving Bottle

Fill a receiving bottle with the turkey baster Isopropyl contents.

Step 8: Label Bottle

Label the bottle "Dehydrated Isopropyl Alcohol"

Step 9: Use Your Dehydrated Alcohol

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

Step 10: Addendum

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.



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190 Discussions


11 years ago on Introduction

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.

5 replies

Reply 3 years ago

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"


Reply 11 years ago on Introduction

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...


Reply 10 years ago on Introduction

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


Reply 1 year ago

and antihistimines are alcohol amines, so benadryl, dramamine, still technically types of alcohol so lots of alcohols but only one (methanol) causes blindness, cocaine is technically an alcohol too because that is cocamethanol, and that doesn't cause blindness, but if you mix it with ethanol, the two get metabolized into one alcohol, cocaethanol


Tip 1 year ago

Freezing the salted-out IPA will precipitate a lot of the dissolved salt.


Reply 1 year ago

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.


Reply 9 years ago on Introduction

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


Reply 2 years ago

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 ;))


Reply 8 years ago on Introduction

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.


6 years ago on Introduction

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.

2 replies

Reply 3 years ago

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.


Reply 3 years ago

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.