Now its time to talk a little bit about paint.
i will try to go into as much detail as possible without being confusing.
the 4 major types of paint i will cover here are as follows:
- Enamel
- Lacquer
- Acrylic
- Urethane
Also, i will add this earlier, rather than later, the acrylic i will be talking about is the water based paints we have available. some manufacturers have taken to calling certain paints ” acrylic enamel or acrylic lacquer” these are not acrylic paints but rather names put on to sell more product when the world is looking for greener painting methods. while there are different things added to each of these 2 sub classes they are nothing more than modified versions of the regular enamels or lacquers and should be treated the same as either.
Starting with the long standby for many modelers, Enamel Paints
By definition, Enamel Paint is: an oil based paint that air dries to a hard, usually glossy, finish.
When applied properly and allowed to cure fully, good ole fashioned enamel paint is resilient, durable and capable of holding up to frequent handling. enamel paints are available in many different forms such as aerosol cans, small bottles and even small tins ( humbrol ).
I have always considered enamel paint to be a slow finish because of the drying time required for the carrier to gas out and harden the paint. In humid areas it can take over a week for the paint to cure hard enough to polish it out. you can cut this time down dramatically with the use of a dehydrator to help “bake” the finish. Enamel paints also have a tendency to go on thicker than some of the other finishes, without proper prep, this can lead to a problem of losing some of the fine details after multiple coats are applied.
As enamels dry they cure by a chemical reaction called polymerization which means the smaller molecules of paint fuse together to form larger molecules as the carrier evaporates.
There is a “recoat” window with enamel paints, this is a “safe time window” in which subsequent coats can be applied without effecting the previous coats. with most enamel you have a 1-2 hour window to recoat, if you miss this window then you will have to wait 5-7 ( longer in humid areas ) days for the finish to cure before applying more coats or your finish may lift and you will have to start over.
Enamel paints can be thinned with either mineral spirits or “paint thinner” . because the dilutent is not considered a “hot” solvent, you can use enamel paints safely over the top of most other finishes without the risk of lifting the underlying finish.
I have also seen many modelers using enamel paint over bare plastic itself without any ill effects of etching the plastic, although this is not something i do myself as i always prefer to prime anything i paint, it is your prerogative.
Now, on to what a Lacquer Paint is: a durable finish that cures strictly by evaporation of the carrier. there is no polymerization process so they dry quicker than enamels.
Another benefit of lacquer paint is that it goes on thinner than enamels, since there is no chemical reaction joining particles together and forming larger ones, you can apply multiple coats and still not obscure fine details which would be buried under a similar treatment with enamel. There is also no limit on the recoat window on lacquer, you can recoat any time you like.
Lacquer paints are thinned with either lacquer thinner, acetone or automotive grade reducer. all three are considered “hot” solvents. This means you cannot use lacquer finishes over a previous enamel paint job as it will lift the paint and destroy the finish. this also applies to enamel primers, hence why i always prime my builds with lacquer primers.
It is not advisable to use lacquer paint on bare plastic, the solvents will etch the plastic giving it a rough bumpy dull finish. and once again do not spray lacquer paint over enamel primer, it wont work out for you.
Acrylic Paints are water based, they have pigment, the carrier is water with extra additives added to cut down surface tension, make the paint flow better, give more gloss and also adhesion promoters.
Companies like tamiya, and createx have an outstanding array of colors for the hobby but once you learn how to reduce things properly you are not just restricted to them. look in your local department or hobby store and you are sure to find an acrylic paint display in the craft aisle. These lend themselves extremely well to brush painting right out of the bottle but can also be thinned and shot through an airbrush without much hassle at all.
because the dilutent is water there are no harsh chemicals or solvents, this makes it safe to spray acrylic paint over any type of finish you like. There is no recoat window so you can respray any time you like. Acrylic paints can also be overcoated with any other type of paint once they are cured fully.
Acrylic is the only paint you can safely paint over bare plastic with no worry of it etching the parts you are painting but it still provides a better finish if they are primed first.
Urethane Paint otherwise known as 2k or two pack paint is directly from the car industry.Urethane paint works by way of a catalyst or hardener. the hardener starts a chain reaction that starts curing the paint and hardening it as soon as it is mixed. You can get single stage urethane paint ( goes on glossy ) or you can do as many do and go with a base/clear system where you lay down your color coats first then when you have the desired hue, bury it under Urethane clear for the glossy shine.
Urethane paints clean up with automotive paint reducer or lacquer thinner. because of the harsh solvents, it is not a good idea to paint it over the top of enamel and i would avoid spraying on bare plastic because it can still etch it.
do not try to save any urethane paint if you have added the hardener, mix only what you think you will need to avoid waste. once the hardener is added, thats all she wrote. dispose of any excess when painting is done and clean your equipment as soon as you are finished, it is near impossible to clean it thoroughly if you let it dry.
A brief word on safety when spraying all but acrylic paints.
Make sure you spray with adequate ventilation, if you are not spraying in a large, wide open area then you need a spray booth. there are plans all over the internet for making budget spray booths so there is really no reason not to have one. A respirator is also recommended if you are spraying indoors as well as eye protection if you are shooting urethanes. ( should wear them for most paints but i know how stubborn we can be ) think of what you are inhaling if you do not spray in a well ventilated area, not only the carrier solvents but the pigments themselves which are designed to HARDEN to create a hard protective shell of paint. do you really want that in your lungs? nah… me either.
i have probably missed out a few things here and there, feel free to leave comments on this section and i will add anything i can to help anyone out.
in Part 3 i will go into the setup process and also laying down color coats.
cya then
Kitbash Korner 