Sufficient Primer? Flat White or Light Grey?

I use Plasticote and Duplicolor.

If its something large like a base or background for a diorama I use the grey/black/white primer from Walmart for $1.29ish.

Thanks for ally he input! I think I'll try a couple different thing to see which I prefer.

I, too like the Tamiya fine surface primer, but have used the krylon & rustoleum primers as well.  I prefer using grey, even if I'm going with white or yellow over it.  Grey is the best you can use for color matching.  If you have a good lacquer paint, that can be used for a primer as well.  The thing you want is something with a solvent that will bite the plastic for proper adhesion.  Another thing that can be done, is a light "buffing" with very fine sandpaper or steel wool.  just enough to roughen the surface, without scratching it.

Reid

Tamiya's Fine Surface Primer is my choice in spray cans. The spray is easy to control and the resulting surface requires very little polishing. For airbrushing, I'm sold on Alclad primers; great adhesion and ready to use as packaged - one bottle goes a long way. Both products are readily available.

mike

Krylon spray can primer is a popular primer. I learned about it from the old newsgroup rec.models.scale (remember newsgroups?).  It is a full bodied primer that covers scratches and stuff very nicely.  However, it is a bit rough and must be sanded well if you intend a good gloss finish over it.  Flat finishes go over it fine.  It has good bite and can even be used under real solvent lacquer.

Use Mr. Surfacer. Rattle can or airbrush. Sprue Brothers has them in stock.

Like dirk says, you'll want to use a primer with acryls.  Unlike enamels or lacquers, acrylics don't 'bite' to the plastic, rather they sit on top.  They're easily scratched off.  You want an inbetween layer that bites down, which your acrylics bond to, and that's a primer.  I've heard Tamiya makes a primer, I've never used it personally.  I've used Testors from a rattle can, I really didn't like it too much.  I've found Vallejo's light grey primer works well, I'm told their white doesn't work too well.  I'm told Mr. Surfacer is a really nice product too, but I've not used it.  Then I'm sure there are generic art store primers, automotive primers, I can't speak for those, but I'd use something meant for styrene.

I like a primer because it gives the paint more "stick". Especially with an acrylic, I think you'll want it.