Perfect primer

Primer can serve many functions during the process of building your model. It can serve as a base color over the plastic to brighten shades that would otherwise be dulled or tinted by the underlying plastic. It can serve as a tooth for paints to grab on to around sharp edges. It may also serve as a check point during heavy filling to see how far you have left to go on that seam, or as a sealer to protect plastic against paints that may be too harsh and craze it. With so many different brands, colors, and types of primer on store shelves these days, just how do you pick the right one for your job?

To prime, or not to prime...that is the question

Personally I prime EVERYTHING no matter how small. I learned my lessons the hard way several times when paint either reacted badly with my plastic or pulled away from the edges and details because it had nothing to grab on to. I also was the victim of trying to paint yellow over black plastic (many years ago). Also when it comes to part preperation, sanding leaves scratches that may show through the paint, however primer is just thick enough to hide these supposing you didn't use anything coarser than 400 grit to start (there will be an article upcoming on part preperation next month).

Which primer should I use?

My personal stash consists of two basic types of primer:

1. General Purpose

2. Finishing

General purpose is exactly as it sounds. This is the primer I use for pretty much every part except the body or any other part I need to be exceptionally smooth. My primer of choice here is Dupli-Color light gray primer/sealer which can be found at any auto parts store or Wal-Mart for $2-3 in a 12oz can. This is also a great "blocking' primer base if you intend to use anything harsher than lacquers and enamels formulated specificly for plastic, as harsher auto touchup paints and nail polish will not eat through it. If you cannot find Dupli-Color, Plastikote T-235 sandable primer works just as well. These products (as any paint) should be used outdoors and with a respirator.

Finishing primer has an extremly smooth grain and can be sanded glass smooth as a basecoat for body work on model cars or natural metal finish aircraft. My preferance is Tamiya fine primer. This stuff is on the pricey side at $7 for a 4oz can but well worth it. Tamiya Primer is available in white or gray shades, however I use the white on most occasions as a base for bright reds, yellows, greens, and blues for model cars. Gray is used as a base under black or metallic colors only. I will often use this as a base for metallic aluminum finishes on auto engines or as a base for the gloss black coat to be used under Alclad metallic lacquers.

Metal PrimersPhotoetch parts and cast white metal or die cast car bodies require a slightly different primer. Metal can have problems with paint adhesion as well as metal can oxidize very quickly when exposed to moisture so a dedicated metal primer to act as a barrier is a must if your surface is one of these. There are several brands like Tamiya, Mr Hobby, Rustoleum experiment and find the brand that works right for you. Personally I like the Tamiya brand since it applies clear so I don't have to worry about covering any odd colored primers.

Colors of PrimerMost commercially available primers are gray, white, black, or red oxide, however they may also come in green, yellow, or other shades. Light gray and white are the best choices for most projects and colors. Red oxide is nice to have on hand in small amounts for 1960's era Ford undersides or as a base for some WWII era German armor. I rarely if ever have used a black primer for anything as it is far too dark to effectively paint anything over it except black and silver.

A note on other types of primers

No matter what anyone tells you, you do not need anything higher grade than standard Pep-Boys grade primer. Many model car builders, especially those in the custom or lowrider sects will tell you to use DuPont Variprime sealer or other types of  auto body shop sealers. These are industrial grade for 1:1 scale auto's used in a large paint booth with adequate protection. I do not recomend using these products as a modeling tool, If you choose to, do so at your own risk!

Keep in mind the products listed here are my own personal preferences. Feel free to experiment and find what works well for you.