Author Topic: 99% vs. 91% Isopropyl Alcohol?  (Read 773 times)

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ednadolski

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99% vs. 91% Isopropyl Alcohol?
« on: October 01, 2019, 10:00:17 AM »
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I use the 91% IPA for cleaning and stripping paint, and I just found out that the 99% strength is available on Amazon.  Has anyone used the 99%, and does it work any better than the 91%?   Is it safe for model plastics?

TIA,
Ed

wvgca

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Re: 99% vs. 91% Isopropyl Alcohol?
« Reply #1 on: October 01, 2019, 10:14:01 AM »
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the 91% is available at walmart, 1 litre for 3 bucks ...  , they don't have the 99%, what's that worth ??

C855B

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Re: 99% vs. 91% Isopropyl Alcohol?
« Reply #2 on: October 01, 2019, 10:16:26 AM »
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Use 99% all the time with the Photon prints... but haven't tried it yet as a paint stripper. Should work a little better, just as safe for plastics as the "weaker" stuff. The magic of 91% is IPA is hygroscopic - it will pull water out of the air and dilute itself, and 91% is where this action stabilizes and becomes slower to seek moisture. Leave a bottle of 99% open and it will become 91% fairly quickly. If you're going to use it to strip shells, you'll want to do it in a closed container.

I learned about this characteristic the hard way in biology class - ruined more than one microscope specimen by leaving the alcohol dish open to air.
« Last Edit: October 01, 2019, 10:19:03 AM by C855B »
...mike

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peteski

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Re: 99% vs. 91% Isopropyl Alcohol?
« Reply #3 on: October 01, 2019, 01:00:47 PM »
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I've been using 99% for years, for the same tasks as you would use the 91% version.  Safe on plastics -  it just has 8% more "oomph".
All this time I have been buying mine in a local hardware store, in gallon size cans.  It is either labeled "isopropanol" or "IPA 99".  I don't think big box stores (like Home Depot) carry it, but the could probably special order it for you.  So can a smaller hardware store (if not in stock). Unless of course the one on Amazon is more convenient (and cheaper).
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learmoia

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Re: 99% vs. 91% Isopropyl Alcohol?
« Reply #4 on: October 01, 2019, 08:42:42 PM »
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the 91% is available at walmart, 1 litre for 3 bucks ...  , they don't have the 99%, what's that worth ??

They have 95%
https://www.walmart.com/ip/Everclear-Grain-Alcohol-750-mL/188219711

 :trollface:

~Ian

Lemosteam

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Re: 99% vs. 91% Isopropyl Alcohol?
« Reply #5 on: October 02, 2019, 08:05:29 AM »
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They have 95%
https://www.walmart.com/ip/Everclear-Grain-Alcohol-750-mL/188219711

 :trollface:

~Ian

Ahahahahaha!  Oh to be 16 again, on a lone wolf summer trip to Denver to meet my brother to help with the drive home. Everclear + cherry koolaid and a large apartment party- oh the pain.  First time I ever had any alchohol (not during the drive of course).  Good times.

nkalanaga

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Re: 99% vs. 91% Isopropyl Alcohol?
« Reply #6 on: October 04, 2019, 01:51:09 AM »
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Isopropyl Alcohol and "Grain Alcohol" are not the same.  Grain alcohol is ethanol, not isopropanol.  Ethanol might work as paint stripper, I don't know, but NEVER drink isopropyl alcohol.
N Kalanaga
Be well

JanesCustomTrain

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Re: 99% vs. 91% Isopropyl Alcohol?
« Reply #7 on: October 04, 2019, 05:36:03 PM »
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91% works just fine as long as the alcohol has a temperature of about 25 to 30 degrees Celsius (what's that, 86 Fahrenheit ?). If the alcohol is too cold it will do barely anything to certain paints.

Jane
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