11 Most Frequently Asked Questions About 99 Isopropyl Alcohol

Isopropyl alcohol (aka 2-propanol or IPA alcohol) has been around since 1920 when chemists at the Standard Oil Company of New Jersey (later ExxonMobil) first produced it while studying petroleum by-products.

This type of alcohol was one of the purest forms of alcohol and had several uses depending on concentration. It's since become the most common and widely used disinfectant in hospitals, pharmaceuticals, and cleanrooms, as well as electronics or medical device manufacturing.

Presently, the USA holds the record for being the world's biggest consumer followed by Asia, Africa, and the Middle East.


While Isopropyl has been around for decades, most people (who aren't chemists or just not into the sciency stuff) still don't fully understand this wonderful chemical.

What People Are Asking About 99% Isopropyl    

If you're one of the curious few, this article will attempt to answer the most common questions people ask about isopropyl, particularly 99 isopropyl, which is as close to pure as you can get.


1. What is 99 Isopropyl? 

The 99 in 99 isopropyl simply indicates its purity. The closer you get to 100, the purer it is. It's important to note that with alcohol, bigger isn't always better. This level of purity comes with several advantages and disadvantages so it's important to determine what you're going to need it for.

99 isopropyl possesses several characteristics due to its type and concentration. Without getting too sciency, they are the following:

  • Fast-drying: 99 isopropyl evaporates quickly, especially if you live in a dry climate.
  • Non-corrosive: Unlike acetone, you can use 99 isopropyl on metals or plastic without being afraid of corrosion. 
  • Odorless: Unlike the scented rubbing alcohol you can buy at the gas station, 99 isopropyl is usually odorless.
  • Minimizes residues: Unlike hard water that leaves residues and stains after drying, 99 isopropyl dries clear and leaves little to no residues. 

Note: We at Pure Chem co. offers 99.9% isopropyl alcohol food grade, available in sizes: quart, gallon, 2.5 gallon, and 5 gallon.

2. What is 99 Isopropyl Used For? 

As we've mentioned:

99 isopropyl alcohol has advantages and disadvantages depending on your needs. At such high purity, various industries have used 99 Isopropyl in the following ways:

  • Eliminate pests in soil and hydroponic systems
  • Cleaning electronic parts that may be damaged by lingering moisture
  • Sterilize and cleanse household equipment
  • Disinfect kitchen surfaces, containers, pots, and trays
  • Completely cleaning your nails before a manicure
  • Perfect for cleaning your grill after grilling (food-grade 99 isopropyl)
  • Use in paint thinner as a solvent
  • Use in windshield thawing agents
  • General-purpose cleaner for most surfaces.

3. What's the Difference Between 99, 91, and 70 Isopropyl?

As you've already learned by now, the only difference between 70, 91, and 99 isopropyl is the amount of water they contain. Since 70 and 91 isopropyl contains a bit more water than the succeeding concentration, this means they evaporate slower.

You may think "that's it?" but there's a deeper effect that this drying time has. It all has to do with how isopropyl works.

You see:

Isopropyl alcohol kills bacteria by coagulating the cell proteins that make up their microscopic bodies. Ideally, you'd want this to work against all of the bacteria's proteins to ensure you eliminate as much of them as possible.

91 isopropyl coagulates cell protein instantly then dries quickly.

That's good, right?

Well, the problem with 91 isopropyl is since cell protein instantly coagulates, it creates a defensive layer that protects the rest of the cell protein. It also doesn't get a chance to permeate the entire cell because it evaporates too quickly.

A 70% solution (70% isopropyl and 30% water) takes longer to evaporate and, therefore, has more time to permeate the entire cell and coagulate its proteins. This is why 70% is more commonly used for everyday antiseptic use on skin and large surfaces.

Since 99 isopropyl dries the quickest, it finds a lot of use in industrial cleaning of water-sensitive objects, where you need things to be clean and dry as quickly as possible. It's perfect for integrated circuit adapters, computer chips, and circuit boards. 99 isopropyl is also great as a topical antiseptic and for cleaning instruments (medical or otherwise).

Since 99 food grade isopropyl alcohol minimizes residues as it dries, it's also a great remover for grease, grime, and other sticky residues. It can even clean the ink off your shirt if you use it immediately after the spillage.

4. Is 99 Isopropyl the Same as Rubbing Alcohol? 


The United States Pharmacopeia (USP) defines "isopropyl rubbing alcohol USP" as containing approximately 70 percent alcohol by volume of pure isopropyl alcohol and defines "rubbing alcohol USP" as containing approximately 70 percent by volume of denatured alcohol.

Ireland and the UK have something comparable in the form of surgical spirit B.P., which the British Pharmacopoeia defines as containing 95% methylated spirit, 2.5% castor oil, 2% diethyl phthalate, and 0.5% methyl salicylate. Methyl salicylate (aka wintergreen oil) is also a common additive to North American rubbing alcohol products.

5. Can I Dilute 99 Isopropyl to 70 Isopropyl?

Yes, you can. If you have some 99 isopropyl just lying around but you need a standard solution (70 isopropyl), you can make some by mixing 2 parts 99 isopropyl with 1 part water. 

6. What Can I Use to Dilute 99 Isopropyl to 70 Isopropyl? 

With the above said:

You can't just use any water to dilute your 99 isopropyl. You can, however, use distilled water, reverse osmosis water, filtered (drinkable) tap water to make an effective 70% solution.

Basically, just make sure the water you're using is devoid of contaminants and other residues.

7. Is 70 Isopropyl Better than 99 Isopropyl? 

As we've established:

This depends on the intended use. 70 isopropyl works great for cleaning your skin and other surfaces but you wouldn't want to use it for electronics.

8. What's the Difference Between Isopropyl Alcohol and Ethyl Alcohol? 

Ethyl alcohol (ethanol) is another common form of alcohol. The main difference between ethyl and isopropyl is their chemical structures: ethanol (C2H6O) contains two carbons and one oxygen while in 2-propanol (C3H8O) the alcohol carbon atom is attached to two other carbon atoms.

Both forms are similar in that they kill germs by disrupting viral and bacterial proteins and lipids. A 65 to 95 percent solution using either isopropyl or ethyl alcohol in any hand sanitizer should do the same job.

9. Can I Drink 99 Isopropyl? 

No. 99 Isopropyl is toxic if consumed directly. There's a reason why you usually find a "for external use only" warning on every bottle of alcohol or sanitizer.

10. Is 99 Isopropyl Dangerous? 

No, but only if used and stored correctly. This includes not drinking it and following storage instructions on its container which usually says "store in a cool dry place away from direct sunlight, heat, or open flames.

11. What's a Substitute for 99 Isopropyl? 

If the surface or object permits, you can use soap with water, bleach, or even vinegar to clean and disinfect surfaces.

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