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Acrylic lacquers & Acrylic enamels?

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  • Member since
    July 2005
  • From: Maine
Acrylic lacquers & Acrylic enamels?
Posted by PontiacRich on Wednesday, February 24, 2010 10:23 PM

Sorry if this is repetetive - I did a search of this forum before posting this!

I just finished the FSM Essential Techniques for the Model Builder and was puzzled by a couple of comments in the article "Airbrush Gallery Top Tips".  One item talks about using "Tamiya acrylic spray lacquers"  and another item talks about "industrial automotive colors, which are predominately urethanes and acrylic enamels"

I'm a bit confused Confused...what is an acrylic lacquer or an acrylic enamel?  Aren't acrylics, acrylics; lacquers, lacquers; and enamels, enamels? Huh?

Please help my sore brain!

Rich - "And when the Band you're in starts playing different tunes, I'll see you on the Dark Side of the Moon" - Pink Floyd

FREDDOM

  • Member since
    August 2005
  • From: Sydney, Australia
Posted by Phil_H on Wednesday, February 24, 2010 11:45 PM

Hi Rich,

I think your confusion is quite understandable. I'm not a paint chemist (or a chemist of any description) but here goes.

Model paint manufacturers would have us believe that Acrylic paints are simply water-based paints and enamels are oil-based paints. However, it is much more complex.

"Acrylic" refers to a class of polymer (or plastic) of a particular molecular structure formed by the joining of smaller molecules (known as monomers) in a process known as polymerisation. When the term "acrylic" is applied to paints, it refers to paints which contain a binder containing these compounds.

Though many uncured acrylic paints are water soluble, it doesn't simply mean that acrylics are water-based paints . I believe that acrylics can also utilise oil based solvents as a reducer. If I recall correctly, after curing, the polymerisation process is non-reversible and if a solvent is introduced to the cured paint, it will break down, but not necessarily into the same original component monomers and so will not re-polymerise. ie. dried/cured acrylic paints may not be reconstituted and re-used. 

The term "enamel" when applied to paints in a generic sense simply means a paint which dries/cures to a hard coating.  However, as noted, model paint manufacturers would have us believe that "enamel" refers to oil-based paints. However, as you may be aware, you can also have water-based "enamel" house paints.

I'm not famiiar with the chemistry involved in oil-based paints but many oil-based paints cure by an oxidation process, where exposure to oxygen in the air polymerises the binder.I'm not sure if this is the case with oil-based , so-called  "enamel" model paints

Lacquer traditionally refers to paints/coatings which simply dry by evaporation and can be re-liquified by re-introduction of the solvent.  The term "Acrylic Lacquer" then, in the true sense, would be a misnomer.

As far as I am aware, Tamiya's spray can line of paints are "synthetic lacquers" Whether they are in fact, an acryliic formulation using a  "lacquer" thinner as a reducer, I don't know.

To further confuse the issue, Tamiya has a range of "enamels" which I believe are actually acrylics using an oil-based solvent. Likewise, Gunze/GSI Creos has a range of "Solvent based acrylics" which use a proprietary lacquer thinner-like solvent.

I've probably confused you even more hey? Dead

Perhaps Ross can shed some light on the subject.

  • Member since
    November 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Thursday, February 25, 2010 9:03 AM

What makes it doubly confusing these days is that some paint does not even identify it as acrylic.

Hobby paints are pretty good about this, but many auto paint rattle cans do not.

Don Stauffer in Minnesota

  • Member since
    January 2003
  • From: Peoples Socialist Democratic Republic of Illinois
Posted by Triarius on Thursday, February 25, 2010 9:47 AM

Actually, it's far more complex than Phil indicates, and the real distinction between lacquer and polymerized coatings is based on thermodynamic character of the binder involved. To make matters worse, the two types can sometimes be combined in the same formulation. This stuff almost makes my brain hurt, and I used to be in the industry.

Now enter the ad-wonks, who will  use misuse and abuse any technical term to make a sale. If they think a word has a particular association in the minds of the general public, they will use misuse and abuse it until it becomes meaningless. In this vein:

"enamel" = durable, hard, etc.

"lacquer" = shiny, bright, glossy.

"acrylic" = can be cleaned up with soap and water

When used by an ad-wonk (as in the label on a can or jar of paint) these terms are MEANINGLESS in terms of actual components. Got that?

In simple but accurate and meaningful lay terms:

lacquer = a coating that can be redissolved in a compatible solvent, and then reapplied to a surface. The initial dried coating (not cured, lacquers don't cure) and the reapplied coating are chemically and physically identical.

polymer coating, i.e., enamel, acrylic, polyurethane, etc. paints = a coating that polymerizes into a new chemical (this is what we call curing) during and after drying. While it may be attacked and redissolved by other solvents, it cannot be reapplied after that.

"acrylic lacquer": no such animal. Acrylic polymers polymerize, or cure. if you see this on the label, it is ad-speak.

"acrylic enamel": ad-speak. This is to get you to believe that although an acrylic polymer is used, and you can clean up with soap and water, the coating is just as durable as the old enamels. Many acrylic coatings are, indeed, just as durable as the old hydrocarbon solvent enamel paints, but because early acrylics were not (some still have adhesion problems) there is an association in the public perception between poor durability and "acrylic."

Because coatings (and other technologies) are complex and require more than the most basic knowledge of science—which most people don't get in our educational system—even those who try to do their homework before writing an article like the one you refer to often get it wrong, or partially wrong. They may have, themselves, felt overwhelmed by the technical aspect of the subject, tried to get help understanding it from someone familiar with the technology, and misunderstood. Then they may have tried to simplify it so the average reader would understand it. The final result is often inaccurate and confusing.

As a case in point, I am quite sure there are some of you whose eyes are crossing as you read the above explanation—which most paint chemists would consider a tremendous oversimplification. I don't even mention whether a coating is a thermosetting plastic or…………Huh?

On the other side, the golden rule of advertising is: "Make them comfortable. Don't ask them to think. Thinking is uncomfortable to the average person." Cynical, but true. They know that if they engage our emotions sufficiently, we won't  think about it clearly, if we think about it at all. Propeller

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

  • Member since
    July 2005
  • From: Maine
Posted by PontiacRich on Thursday, February 25, 2010 3:39 PM

[View:/themes/fsm/utility/:550:0]

Rich - "And when the Band you're in starts playing different tunes, I'll see you on the Dark Side of the Moon" - Pink Floyd

FREDDOM

  • Member since
    August 2005
  • From: Sydney, Australia
Posted by Phil_H on Sunday, February 28, 2010 7:21 AM

LOL...

Ross, I think people's heads must have spun fast enough to achieve VTO from their chairs when they read that.

I'm often tempted to pick up a jar of Tamiya enamel when I visit my LHS, but then I think, "why start and have to support (thinners, cleaners, brushes etc) a system which duplicates exactly the same colours that I already have?" I suspect that these paints will also thin with lacquer thinner too.... (no, not going there - lol) 

  • Member since
    October 2007
  • From: Scotland
Posted by Milairjunkie on Tuesday, March 2, 2010 5:14 AM

Triarius

I am quite sure there are some of you whose eyes are crossing as you read the above explanation

Not in the slightest, it makes very interesting reading, so feel free to enlighten us.

Are there any site or publications those interested in the subject might find usefull?

  • Member since
    January 2003
  • From: Peoples Socialist Democratic Republic of Illinois
Posted by Triarius on Tuesday, March 2, 2010 11:14 AM

You could try convincing the editor of FSM to publish the article on the subject that I sold him over a year ago.

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

  • Member since
    December 2020
Posted by PhilipZ on Wednesday, December 9, 2020 9:08 AM

Immensely helpful information Ross, much appreciated. Based on your explanation could Humbrol paints actually be acrylics? And what would you categorise "Allclad Lacquers" under? I would appreciate your views on these questions as I am in the hobby shop industry and regularly get questions around what the difference between those two "Enamel' and 'Lacquer' paints are as oppsed to acrylic paints.

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