Confused - enamel and water-based paints

[Michael Morris]

A few years ago I returned to the building plastic models after a VERY long hiatus.  Staying with what I knew, all my kits have been hand painted with enamel paints.  I'm now planning on taking the plunge and buying an airbrush.  So, what paints should I use.  Looking at some youtube videos, most people seem to now use acrylic paints in airbrushes.  Is this the case?

1. What are the advantages of using acrylics over enamels in an airbrush?
2. Can I paint a coat of acrylic over a coat of enamel or indeed visa versa?

Thanks

[Troy Smith]

1 hour ago, Michael Morris said:

So, what paints should I use.  Looking at some youtube videos, most people seem to now use acrylic paints in airbrushes.  Is this the case?

No. Plenty of airbrush enamel users.

@Jamie @ Sovereign Hobbies  makes enamel paint and swears by it , but swears at acrylic....   

 

It should be noted that there are water based (Revell aqua, Vallejo) and, a kind of lacquer based acrylic as well.  (Tamiya, some Gunze) which can be thinned with cellulose thinners, 

 

I have to say, just too many variables,  you will get answers here from users of all types, with postives and negatives from each side.

 

Acrylics in short are not as tough, but the water based are less toxic, enamels require use of petroleum based solvents, requiring more and better ventilation and/or facemasks. 

 

I should be noted there are plenty of modellers here who still brush paint and get excellent results, both with enamel and acrylics,   but you don't get groovy youtube videos of those.

While there are some excellent videos, many I encounter are 'fashion'  lost of bells and whistles,  pre/post shade, Spanish school weathering etc etc, and make "wow" models.... that look sod all like the real thing. (and are frequently full of accuracy mistakes too)

 

In fairness,  its their model, to do with as they wish,  it's a hobby,  if you like accuracy it''s 'wrong' if you like artistry and technique it's 'right' 

 

Looking at you interests, when you say spacecraft, these real or sci-fi?   If the latter, then bells and whistles finishing is a plus for example.

 

Sorry, not the best answer,  and I need to switch off and sleep now,  but hopefully given you a few more pointers.

 

If there is anywhere nearby who runs airbrush course or demonstrations, that might be worth checking out as well. 

 

HTH

 

 

 

 

 

 

[Rabbit Leader]

As a general rule of thumb it is always best to stick to one medium of paint throughout a build, however I regularly use different types for different applications / areas.
 

Lacquer paints such as Gunze Mr. Color are as tough as old boots when applied to bare plastic and go on very well when mixed with Gunze’s own Levelling thinner. The smell and toxicity of it may not make you the most popular member of the household, however the results are so good you will be happy you went there. 

Enamel paints are still very serviceable and I still use my old range of Hunbrols and Tamiya Enamels just as much as my Lacquers. Best to stick to the same paint companies home brew thinner, however other types will work well too (at times). 
 

Acrylics are the safest to use, however many modellers both swear by them and at them. They have less bite than the other two types and are prone to lifting under masking tape. Acrylics also work best under a primer coat which will normally be lacquer or enamel based anyway? 
 

As Troy has said, there’s 1000’s of reasons to use and not to use the various types of paints mentioned. I recommend buying a tin of White paint in each of the various mediums and see which one works best. If you can happily spray white (or yellow) then your on your way! 
 

Cheers.. Dave 

[VMA131Marine]

6 minutes ago, Rabbit Leader said:

Acrylics also work best under a primer coat which will normally be lacquer or enamel based anyway? 

Vallejo sells water-based polyurethane primer which I have found works very well. It comes in different colours as well so it can double as the base colour for the model. I have to admit to really liking Vallejo Air and it is generally pretty resilient to masking. I’ve used AK Interactive colours as well and they seem to be more prone to lifting as masking tape is removed. 

 

That said, Gunze Mr. Color lacquer based paint it just brilliant as long as you thin it sufficiently. If you don’t, the grey shades especially will produce what appear to be cobwebs forming on the model. Mr. Color is also not great for brush painting large areas.

[Space Ranger]

This gets complicated. The general rule that I have followed since so-called "acrylics" were introduced is: "acrylic" over enamel over lacquer, but not the other way 'round. However, this depends on what kind of "acrylic" we are talking about, and this is where chemistry enters the picture. Most people use the term "acrylic" to refer to water-miscible paints such as Tamiya's. But not all "acrylics" are equal. A paint is composed of a pigment (color), a vehicle (the carrier liquid), and a binder (the film-forming component of the vehicle that holds the pigment in place after the paint dries. "Acrylic" may refer to the pigment (synthetic as opposed to organic), or the binder (synthetic as opposed to organic, such as linseed oil or a petroleum-based oil solvent). Most hobby "acrylics" are, I believe are those with synthetic pigments and/or binders, usually in a water-miscible (mixable) vehicle. But some "acrylics" are acrylic lacquers (acrylic pigments in a quick dry solvent that contains nitrocellulose resin, another organic substance), and some are acrylic enamels (acrylic pigments in a petroleum-based solvent).
Enamel paints use a process that allows polymers in the paint to set and bond together so when the paint hardens, it will not soften again. This is why you can brush additional coats over the original coats once they have cured. In contrast, lacquer paint dries when the solvent has evaporated and can soften over time or dissolved with the application of additional coats. Tamiya "acrylics" are technically enamels, using acrylic pigments which polymerize in an organic solvent — alcohol — which just happens to mix with water.

 

From a practical standpoint, "acrylics" don't smell as bad as conventional enamels or lacquers, which may be important depending on your domestic situation. But they are tricky to spray; they tend to dry on the tip of an airbrush without additives such as "flow improvers", meaning frequent cleaning is required. They invariably require a primer because they don't adhere as well as enamels or lacquers. And, even with a primer, masking tape may pull them off. And there are so many brands available now, it usually takes a lot of experimentation to get the right combination of paint, thinner, additives, and air pressure. And a combination that works for one brand may not work for another!

 

I'm 73 years old. I don't have time to play paint chemist to get an "acrylic" to work. I spray only enamels (Humbrol, Colourcoats, Xtracolor, Model Master) thinned 50/50 with mineral spirits or lacquer thinner or a combination of both and have never had an issue in 60+ years of building models (50 or so using an airbrush). The only use I have for "acrylics" is as washes, heavily diluted with water or alcohol. In that case I use Tamiya's.

[Giorgio N]

11 hours ago, Michael Morris said:

1. What are the advantages of using acrylics over enamels in an airbrush?

 

First advantage is that the paints, the thinners and the products used to clean the airbrush are less smelly and toxic. Sounds like a small problem but if you don't have a dedicated space for modelling then it' something that can have a big impact.

Most important advantage from a modelling point of view is the drying time: using water based acrylics I can paint a camo scheme in less than the time that enamels require for the first coat to set. Of course the short drying time also leads to problems with the paint drying on the airbrush tip but there are ways to sort this.

Another advantage is that in my experience it's easier and quicker to clean an airbrush after using acrylics, but this depends on the cleaning products available. In my country denatured alcohol is available in every supermarket for cheap and this dissolves any trace of acrylic paint from an airbrush in almost no time.

Last but not least, again from my personal point of view: in my corner of the world it's easier to find good quality acrylic paints than good quality enamels in the local shops...

 

 

11 hours ago, Michael Morris said:

1. Can I paint a coat of acrylic over a coat of enamel or indeed visa versa?

Thanks

 

Really there's no problem in using one type of paint over the other, as generally the thinners used for acrylics does not affect enamels and viceversa.

What is important to remember is that whatever paint was used for the lower coat, this must be properly dry and set before painting on top. There are paints that may be dry to the touch but are still curing under the surface, if another paint is used on top this can ruin the lower coat.

 

It's also important in general to understand what the term acrylics means. When it comes to model paints, there are two "families" that behave very differently even if both are defined as acrylics: Tamiya and Gunze acrylics on one side and the various Vallejo/Lifecolor/Xtracrylics on the other. The former can be thinned with water but really their thinners are alcohol based. The latter prefer to be thinned with water and will react badly when thinned with certain alcohols. Both familes have their pros and cons, with Tamiya and Gunze much easier to use in an airbrush but more difficult to use with a brush