Before painting: is a primer really necessary ?

I rarely use a primer; why add to the thickness of the paint? Most model paints adhere well to plastic without primer. When they don't or you're trying to even out a conversion/putty job, then is the time for primer. hth

The Keeper (of too much crap)

There are three reasons for primer. One is color. If you are painting a color vastly different than the molded color, there can be variations that a neutral grey primer overcomes.

Second is having paint take a bite. If you wash styrene well, this is generally not an issue, but some resin bodies do not take paint well without primer.

Third, a good primer allows you to see how well you have sanded and smoothed seams. The primer shows sand>

in article snipped-for-privacy@mb-m29.aol.com, Keeper at snipped-for-privacy@aol.comedy wrote on 7/1/04 9:43 AM:

I rarely prime for any but NM finishes. Generally, there is no point to it, IMO other than to "prove" filling or seam work since most paints don't require it.

NM however works better if applied over a primer that both seals and fills the minute dings, dents, and scratches that will readily appear in the final finish.

MB

It depends on if you want (or need) the benefits that the primer affords. The primer will fill in a few basic seams (nothing major). It also will give you a solid color so you can tell if you've got any particular seam sanded/puttied out or if you need to give it a bit more attention.

The other main thing, is with paint adhesion. Now, if you're using enamels then this likely will not be a problem for you. If using acrylics though, you might run into some problems. Certain paints (like Testor's Acryl or the craft type paints at Wal-Mart or Michaels) will not stick well to smooth plastic, and will peel right off if you place masking tape on them. If you notice this happen, then you will need to prime the model before painting it. Now, personally, I tend to use quite a bit of the craft paints (they're pretty quick and cheap, and when thinned right produce a good finish). For that reason I prime every model I build. Not necessarily every part, but any major assembly. After the primer coat the paint will not pull off so easily and I can paint as needed.

Light or dark colored primers also will have a very small effect on the warmth of the paint job after finishing, but it's not something I have noticed to any great degree (I use the standard neutral gray primer though which I doubt would have any effect).

I am currently building a Revell Peterbilt fire truck. Many of the parts that need to be red are cast in black and many of the parts that need to be black are cast in red - go figure! I spray everything with a medium grey first and it all works out. Don't spray red onto black plastic, nor black onto red plastic - neither gets the right shade. David Pennington snipped-for-privacy@bbbweb.com

Hi,

I have found that when building models, using a primer allows me to check how well I have sealed the joints and seams.

Make sure you use a thin primer so that you do not hide other details.

If the color of the finished model is light, use a light gray primer. That helps the final coat cover more efficiently else you can use a darker primer.

Sincerely,

Jim klein

Depends on the paint you prefer. You're probably better off using a primer with acrylics, but I've been using enamels for nigh onto frty years and never used a primer coat once...unless you count laying a silver base coat on some of my jets, but I'm over that one now.

Could you give us the brand names of a few of these craft paints that you've used successfully? Jerry 47

When building aircraft I generally don't use primer. The exception would be a kit moulded in a translucent plastic. I find those make it difficult to judge the surfaces.

Under autos I've gotten into the habit of primering if only to give the top coat a different shade. Metallics and pearls can look very different depending on the colour over which they're applied.

Bill Banaszak, MFE