Paintology – Part 2 – the Products

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

Paintology – Part 1 – Preparation

Let me start the article by stating a simple fact.

I am not an expert!

But i am someone who has been around the hobby for over 30 years and do have considerable experience. I also have a background working on and painting 1:1 vehicles and the process is no different regardless of scale.

I do have paint problems, but when i do i strip the parts and start over. until i get the finish i want and am happy with. Patience is the key with any type of finishing and i have fallen into the trap of impatience more than once over the years and had to pay for it by stripping and redoing something. it is all part of the game and should be viewed as a learning experience rather than a failure.

By the time i am done with this 4 part article i hope to be able to explain not only the Process of prepping, priming and painting a kit but also the different types of paint available to us but also the benefits of having so many different choices when it comes to finishing out models.

The entire process is neither fast or fool proof. there are always exceptions to every rule when paint is involved. temperature and humidity can play large factors in how paint preforms. By the time i am done i hope to cover as many different aspects as possible and maybe the information can help someone having problems or new to the game understand a bit more about the process.

The nature of the beast is to remember, paint does not always like to play nice, there are times when you do everything perfectly but something still goes wrong. Keep your head up and start over. It is not the end of the world and the hobby should not be about speed, if you are looking to complete a kit in a weekend then i dont recommend you even bother reading this article. The prep stages themselves can easily take 2 weekends or more depending on how perfect you want things.

The way i view things through my own eyes is, the cost of kits has gone up considerably over the years, i have no problem taking 6 months to build a kit as long as when i am done, it is done the way i wanted it. I get my money out of each and every kit i buy and sometimes strip them down to nothing and rebuild them again in a different incarnation depending on my mood. If i just wanted a model to quickly throw on a shelf for display i would have bought a completed one and bought something else to build.

What is Paint?

Paint, by definition is, “a colored substance that is spread over a surface and dries to leave a thin decorative or protective coating.”

Almost all paints have atleast 3 major components, the binder, the carrier and the pigment.

Binder = this is the only component that must be present in all paints. the binder serves multiple functions as it greatly influences the characteristics of the finished paint. It promotes adhesion to the surface, and controls aspects of the paint job such as flexibility, durability and gloss.

Carrier = the carrier can also be known as the solvent. the carrier is what governs the paints viscosity, or liquidity. There are some paints that do not have a carrier, they are very thick and require thinning by the user in order to preform each task needed. The carrier is engineered to evaporate from the completed paint job leaving only the binder and pigment behind.

Pigment = The pigment of any paint has one job, to impart color into the final finish. Not all paints have pigments in them. ( think clear coats ) Pigments can either be granular solids or even dyes. Without some type of pigment, there is no color.

Other additives may be combined from the manufacturer to help improve the flow of the paint by altering the surface tension, and improve surface appearance.

      Now before i go into detail about paint itself, i have to have a word about surface preparation. 

A paint job can only ever be as good as its surface prep. Paint does not hide imperfections, it intensifies them. Be sure to have all of your bodywork done ( seams, mold lines, ejection pain marks and putty feathered out ) before you even think of grabbing the color coat.

Prime everything. either match your primer to your color coat ( by brand ) or use a good quality Urethane or Laquer primer. i avoid using enamel primers at all costs and i will explain that a bit more shortly.

I know there are people stuck in their ways that will tell you ” i paint without primer and have never had a problem so i am not going to change now” , do you really want to bank on their luck carrying over to your builds?

The primer coats serve two different purposes, firstly they will allow you to see the surface flaws and correct them before color hits the car ( yes this requires sanding and repriming until smooth ). The primer coat also acts as a barrier so the solvents in your color coats cannot attack the plastic and craze it ( crazing is when the solvent eats into the plastic creating a rough surface )

How do i Prep a kit?

The way i do it is not the only way in the world, and yet it does work well. Feel free to try other variations if you like and let us know how they turn out.

Prepping a kit for me starts just after i open the box. I drag it off to the kitchen and fill either the sink or a large bowl with warm water and a bit of dishwashing detergent in it. i submerge the parts into the water and let them sit for 5 to 10 minutes, then using a soft brush or a toothbrush, i lightly scrub the parts before rinsing them off and setting them aside to dry. you can either air dry them or cheat like i do and throw them in my dehydrator for a while until no water remains. This first process removes any residual mold release agents the manufacturers may have left behind, these contaminates can easily ruin a paint job so a bit of patience is well worth the effort here.

Next i visually inspect the kit, removing any noticeable flash ( the thin edges of plastic left behind by the manufacturer ) then i trim the parts to be painted off the sprue’s. i do not cut the parts off directly, when possible i cut the sprue itself close to the part and then using a hobby knife or razor saw i remove the piece of sprue from the part leaving as little cleanup as possible. ( do not ever just bend or twist the parts off the sprue, you are only creating more work for yourself if you do).

Next step is to mount the parts for priming. You can do this in a number of different ways.

small parts

• use glue to mount the pieces to small pieces of styrene being careful to have the glue areas somewhere that will not be seen on the finished piece



• drill a hole in a small hole where it will not be seen and insert a tooth pick into it



• use a small piece of masking tape reversed on the tip of a popsicle stick and adhere your small parts to it
• for pieces with protruding tabs you can use alligator clamps mounted on dowels or skewers to hold some of them, providing the tabs will not be visible on the finished model

Larger parts like body panels, shells, chassis pans and interior buckets

• make a cheap and cheerful body holder from a scrap piece of 2×4 and a coat hanger

I have also seem people use anything from beer cans to spray paint cans wedged inside the body to hold it during paint. the only reason i dont recommend doing it that way is that it is too easy to have the body accidentally fall off the can when maneuvering the body for a better spray angle. one drop with wet paint and you have to start all over again.

Once you have your parts secured for painting, you are halfway there.

Think Ventilation– The process of painting creates overspray and releases volatile chemicals into the air ( the carrier ). As a general rule, you do not want to be breathing this in your lungs. there are 101 different tutorials on making a cheap and economical spray booth from anything from a large cardboard box to a tupperware container. at the very least, if you are not going to construct a spray booth, atleast paint in a large open area and wear a mask. The hobby is not worth shortening your life over.

Think Overspray– The process of painting also inherently creates overspray ( excess materials that are carried either from the aerosol can or airbrush and do not land on the part but float in the air instead ) these can cause damage not only to your lungs but also to property. do not set up to paint one of your model cars out in the garage next to your parents new car. neither you or they will be happy with the outcome.

Got your ventilation sorted out?

no worry of overspray?

OK

How i prime:

Since i use a “hot primer” (Laquer primer) i build my primer coats up slowly. Using mist coats ( minimal primer in fairly quick passes with no intention of full coverage on each coat ) using mist coats does not allow enough of the primers carrier (solvent) to flood the body causing etching. by applying multiple mist coats at 10-15 minute intervals you can achieve full coverage in about an hour. this guarantees two things if done properly, the primer coat will be as thin as possible helping you to retain details in the kit and allows for a solid foundation for any bodywork that needs to be preformed.

once the primer coat has cured for a day (2 hours if using a dehydrator) you can begin your bodywork without worry about the primer being soft.

You will notice at this point why primer is so important. Primer makes it possible to see surface flaws that you would not be able to see if just looking at bare gloss plastic. mold lines will be more apparent, seams and flash you didnt notice will, all of the sudden, be in plain view. now is the time to address these flaws with either wet/dry 800 grit paper or sanding sticks. on some kits you will also find sink marks that need attention, the best example i can think of recently is on revells 57 chevy kit. admittedly you do not need primer to see this one but it is the best example i have of what a sink mark looks like.

use your body filler of choice ( i prefer 2 part automotive glazing putty over single part air dry putties because they cure by chemical reaction instead of evaporation, evaporation = shrinkage over time. i would rather not look at a finished kit 6 months from now to find the putty shrunk and ruined an otherwise excellent build ) apply the filler, let it cure and then sand to feather the edges into the surrounding bodywork.

once you are sure you have addressed the bodies issues it is a good idea to use the back of a hobby blade to clear out any door, trunk or panel lines to prevent prime and paint buildup from obscuring them later. then it is time to reprime the parts again using the same process as before until you have nice even coverage.

let this cure again for as long as it takes. once the finish is dry, look the body over again, see if you missed anything. if you did then now is the time to address it and reprime. if you are happy with the current condition of the body then you can start gearing up to move to the next step.

the next step in a quality finish is to wet sand the primer with 1000 grit wet/dry paper. your goal is not to brake through the primers surface to the underlying plastic and bodywork but rather to smooth out the top layer of primer to be as smooth as possible for the color coats. take your time and work carefully around moldings, door handles and emblems. the more time you take in prepping properly, the better chance you have of a contest quality finish. if you accidentally break through the primer to plastic, dont get too worried, you can go back and spot prime the areas and then wet sand again until the finish is uniformly smooth.

when you are happy with the finish of the primer coat then take the kit bask to the sink, bring your toothbrush and give it a light soak and scrub again. this will remove any oils from the body that were transfered from your hands during the sanding process. yes even those oils can effect your final finish. also make sure you use the toothbrush to clear the panel lines and recesses. when you are happy its clean then set it aside to dry again..

yes this is a slow process but it is all worth it in the end and the patience you show now will pay large dividends in the end result.

The paints i am going to cover in the next installment of this article are as follows:

• Enamel
• Laquer
• Acrylic(water Based)
• Urethane