90% + isopropyl?

LateBloomer

Member since
December 2005
From: Portland, Oregon

90% + isopropyl?

Posted by LateBloomer on Saturday, February 25, 2006 8:26 AM

Hi guys,
Well I have been spraying with my new 150 and I must say my, my. I likey. The weight in the hand is comforting and it sprays very nice. Time to practice, practice, practice. Since getting all those useful/helpful tips I'm happy to say that my Aztek is now behaving properly so that is a nice plus. Cool [8D]

New question if you please. I have been reading that some users are using + 90% rubbing alcohol with acrylic retarder in lue of X-20A, which is pretty spendy, where does one find 90% and higher rubbing alcohol? I have searched the drug stores and I seem to find only 70% rubbing alcohol. *scratching head* Confused [%-)]

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jcfay

Member since
November 2005
From: Chicago, IL

Posted by jcfay on Saturday, February 25, 2006 8:44 AM

You are looking in the right place. I got my bottle of 91% isopropyl at a Rite Aid drug store here in Pittsburgh, and I know that it is available at many drug stores (and if you're in OR, then I'm sure they have it there too unless there is some freakish law that prevents stores in OR from carrying it). The 91% is usually right next to the 70%. Hope you find some. I haven't tried the isopropyl + retarder as a substitute yet, but I will soon. It will be nice to save a buck Smile [:)]

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Bgrigg

Member since
May 2005
From: Left forever

Posted by Bgrigg on Saturday, February 25, 2006 9:41 AM

Yes, the 150 is a great airbrush (I have two!) isn't it? Big Smile [:D]

You may have to ask the druggist as some places may be required by law to keep it behind the counter (sometimes the law is an @$$). Here in Canada I can buy 99% off the shelf. But I have to ask for dust free latex gloves. Go figure!

So long folks!

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Triarius

Member since
January 2003
From: Peoples Socialist Democratic Republic of Illinois

Posted by Triarius on Saturday, February 25, 2006 10:49 AM

Even where it is not kept "behind the counter" it is often separated from the "rubbing alcohol" which is 70 percent. It's not always easy to find until a clerk shows you where they've squirreled it away.

Failing that, try a hardware store. I know some Ace hardware stores carry it. If you do go the hardware store route, be sure to read the label—avoid anything that has other organic solvents (like methyl, ethyl, butyl, or propyl (different from isopropyl!) alcohol.

Ross Martinek A little strangeness, now and then, is a good thing… Wink

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LateBloomer

Member since
December 2005
From: Portland, Oregon

Posted by LateBloomer on Saturday, February 25, 2006 10:51 AM

heh. I know what you guys mean. I should be able to find it somewhere. I mean, hell OR sells 190 proof grain alcohol so I should be able find the 90%. Hmmm.... Maybe I should just use the grain alcohol.... Evil [}:)]

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Triarius

Member since
January 2003
From: Peoples Socialist Democratic Republic of Illinois

Posted by Triarius on Saturday, February 25, 2006 11:15 AM

LateBloomer wrote:
heh. I know what you guys mean. I should be able to find it somewhere. I mean, hell OR sells 190 proof grain alcohol so I should be able find the 90%. Hmmm.... Maybe I should just use the grain alcohol....

NO! NYET! NINE! Grain alcohol is a marvelous general purpose solvent and cleaning agent, but it plays hell with many acrylic paints, particularly Tamiya, at least some Gunze, some PolyScale, and all the Testors acrylics I've ever tried it with.

This is because concentrated ethyl alcohol is a powerful dessicant—it dries out paint just as it dries out your skin—and can cause severe flocculation (how's that for Scrabble word!) or clumping, and may alter the behavior of the coating polymer. It may harden in the airbrush, or never harden on the model. Additionally, it evaporates so rapidly that the paint may reach the model as dry dust.

One of the functions of what modelers call "thinner" is not thinning, but dispersion. The thinner, (properly called a reducer for this reason) makes the paint mist finer by evaporation as the mixture leaves the nozzle. Evaporation of the solvent pulls the tiny droplets of the mist apart into even finer droplets, helping to produce a finer, more uniform finish on the target surface.

That being said, small amounts of ethyl alcohol can be used as an additive to increase dispersion and enhance spray performance under humid conditions, particularly very humid or humid and cold conditions. The amount would be on the order of one or two drops per quarter ounce. In my experience, this works with PolyScale and at least some Testors acylics. It is not necessary or recommended with Tamiya or Gunze thinned with 90 percent isopropyl.

Ross Martinek A little strangeness, now and then, is a good thing… Wink

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grandadjohn

Member since
February 2003
From: phoenix

Posted by grandadjohn on Saturday, February 25, 2006 11:38 AM

I use 70% when I airbrush and I mainly use Tamiya paints,with no problems

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Triarius

Member since
January 2003
From: Peoples Socialist Democratic Republic of Illinois

Posted by Triarius on Saturday, February 25, 2006 11:53 AM

grandadjohn wrote:
I use 70% when I airbrush and I mainly use Tamiya paints,with no problems

I've heard this before, from others, but when I've tried it, the result was disasterous. I suspect that the problem, or potential problem, results from impurities in some of the 70 percent isopropyl that are incompatible with the Tamiya resins. This means that whether or not 70 percent works will vary from one supplier to the next—This month, the stuff from Walgreens works, next month, the stuff from CVS Pharmacy works, but Walgreens doesn't.

So I stick with 90 percent and don't worry about it.

Ross Martinek A little strangeness, now and then, is a good thing… Wink

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Bgrigg

Member since
May 2005
From: Left forever

Posted by Bgrigg on Saturday, February 25, 2006 11:58 AM

Triarius wrote:
...and can cause severe flocculation (how's that for Scrabble word!)

Sounds like a great scoring word, but I don't think you would be able to spell it without cheating! Wink [;)]

You've been using some great words lately, Ross: cephalalgia, surfactant, and now flocculation. I'll have to bone up on some 25¢ words. Now where's my Roget's?

Normally I eschew obfuscation! Clown [:o)]

So long folks!

Reply

Triarius

Member since
January 2003
From: Peoples Socialist Democratic Republic of Illinois

Posted by Triarius on Saturday, February 25, 2006 12:15 PM

Bgrigg wrote:

Normally I eschew obfuscation!

But if you cook it right, you don't have to Sign - Dots [#dots]

Ross Martinek A little strangeness, now and then, is a good thing… Wink

Reply

LateBloomer

Member since
December 2005
From: Portland, Oregon

Posted by LateBloomer on Saturday, February 25, 2006 12:45 PM

Triarius wrote:
LateBloomer wrote:
heh. I know what you guys mean. I should be able to find it somewhere. I mean, hell OR sells 190 proof grain alcohol so I should be able find the 90%. Hmmm.... Maybe I should just use the grain alcohol....

NO! NYET! NINE! Grain alcohol is a marvelous general purpose solvent and cleaning agent, but it plays hell with many acrylic paints, particularly Tamiya, at least some Gunze, some PolyScale, and all the Testors acrylics I've ever tried it with.

This is because concentrated ethyl alcohol is a powerful dessicant—it dries out paint just as it dries out your skin—and can cause severe flocculation (how's that for Scrabble word!) or clumping, and may alter the behavior of the coating polymer. It may harden in the airbrush, or never harden on the model. Additionally, it evaporates so rapidly that the paint may reach the model as dry dust.

One of the functions of what modelers call "thinner" is not thinning, but dispersion. The thinner, (properly called a reducer for this reason) makes the paint mist finer by evaporation as the mixture leaves the nozzle. Evaporation of the solvent pulls the tiny droplets of the mist apart into even finer droplets, helping to produce a finer, more uniform finish on the target surface.

That being said, small amounts of ethyl alcohol can be used as an additive to increase dispersion and enhance spray performance under humid conditions, particularly very humid or humid and cold conditions. The amount would be on the order of one or two drops per quarter ounce. In my experience, this works with PolyScale and at least some Testors acylics. It is not necessary or recommended with Tamiya or Gunze thinned with 90 percent isopropyl.

I was just kidding about the grain alcohol. Wow!! [wow]

But its nice to know in case I ever got INTO the grain alcohol and decided to give it a whirl. hehe. *shudder* That is some strong stuff.

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