91% IPA vs 99% Isopropyl Alcohol

[Miatatom]

Can 99% IPA be used in place of 91% IPA?

[Spruslayer]

Thats what i use for my home brew thinner,works good for all my acrylics

[peteski]

I don't see why not - it is 8% stronger.  I buy IPA 99% by the gallon in a hardware store.

[Ace-Garageguy]

2 hours ago, Miatatom said:

Can 99% IPA be used in place of 91% IPA?

The only difference is that 91% has more water in it.

You can make 99% into 91%, if you want to, by adding an appropriate amount of distilled water.

[Dave G.]

Ace beat me to the answer. Actually I use 91% in my home brew thinner for acrylics. Since covid I've only been able to get 70% locally so I adjusted the water in the home brew to 20% less which is more than close enough. Still use the same amount of Liquitex retarder to control tip dry and aid flow out. . I've saved my 91 for cleaning but find that 70 cleans just about as well.

[randyc]

So I have 50, 70 and 90.   And you guys are saying the 90% works best?  Just asking.  I found that 50% works good for thinning down for washes.   Haven't experimented with much other than brush painting.

Edited August 11, 2020 by randyc

[Dave G.]

4 minutes ago, randyc said:

So I have 50, 70 and 90.   And you guys are saying the 90% works best?  Just asking.  I found that 50% works good for thinning down for washes.   Haven't experimented with much other than brush painting.

Well we're  making a thinner blend for airbrushing acrylics. I can't speak for the others but mine needs 30-32% actual or true alcohol content. So the distilled water gets adjusted accordingly to that, the real alcohol content in the blend is around 30-32% in my case. You need to understand that all the numbers you mentioned, the other part of that to make up 100% in your bottle is already water. That's all that is in there. So Then, to every 3 oz of thinner I make up I add x amount of Liquitex retarder according to season. And of course there is fudge room to mess with. For the acrylics I use I find this nearly perfect. A few guys copied it and love it. One tried to cheat the retarder, then cheat the brand of retarder and it totally flopped for him. Once he got it all straight in his head he was golden.

[randyc]

25 minutes ago, Dave G. said:

Well we're  making a thinner blend for airbrushing acrylics. I can't speak for the others but mine needs 30-32% actual or true alcohol content. So the distilled water gets adjusted accordingly to that, the real alcohol content in the blend is around 30-32% in my case. You need to understand that all the numbers you mentioned, the other part of that to make up 100% in your bottle is already water. That's all that is in there. So Then, to every 3 oz of thinner I make up I add x amount of Liquitex retarder according to season. And of course there is fudge room to mess with. For the acrylics I use I find this nearly perfect. A few guys copied it and love it. One tried to cheat the retarder, then cheat the brand of retarder and it totally flopped for him. Once he got it all straight in his head he was golden.

Excellent.   I haven't had much luck airbrushing acrylics yet.   What does the alcohol really do?  It is a solvent that evaporates pretty quick.   Then you add retared to slow the evaporation?  I figured the alcohol/water/other percentages were as you said.  I still have a LOT of NOS Testors, so just starting to touch into acrylics.   But glad I found this.  So even with 50%, I need a little bit of water to lower the alcohol percentage?  

What brand of paints are you using?  Currently I only have a few Testors MM acrylics for interiors and such as that.   Have not tried to paint a body yet.  

[Dave G.]

1 hour ago, randyc said:

Excellent.   I haven't had much luck airbrushing acrylics yet.   What does the alcohol really do?  It is a solvent that evaporates pretty quick.   Then you add retared to slow the evaporation?  I figured the alcohol/water/other percentages were as you said.  I still have a LOT of NOS Testors, so just starting to touch into acrylics.   But glad I found this.  So even with 50%, I need a little bit of water to lower the alcohol percentage?  

What brand of paints are you using?  Currently I only have a few Testors MM acrylics for interiors and such as that.   Have not tried to paint a body yet.  

It works in most acrylics, just mix some up and let it sit covered for 4-5 minutes, if it's a paint that will react it will get stringy, turn to glue or else separated never to go back together. DecoArt for instance is the only craft paint so far that reacted once and I use several brands of craft paint. Thus far no acrylic model paint has been an issue in these ratios of alcohol. Tamiya gloss will work but you will get better gloss from lacquer thinner with that paint. The flats are ok. Model Master acrylic shoots exceptionally nice with it, you're gonna like it just be sure to prime first. You should always prime first with acrylics, they bite primer great and plastic terrible lol ( no, I mean literally terrible) !!

Just trust that the blend works better than water ( I've spent two years playing with different means of thinning acrylics conducting spray tests, drying, scratch tests, water alone is rarely the answer), it sprays more like solvent paint with the alcohol in there is best I can tell you. The basic formula came from Bobby Waldron at Genesis Models fwiw. I'm in agreement with his comment that this is pretty universal thinner.

Edited August 11, 2020 by Dave G.

[Dave G.]

27 minutes ago, Dave G. said:

nt

 

Edited August 11, 2020 by Dave G.