Using Tamiya Surface Primer for Plastic & Metal(gray)

Personally, I always use primer. I've found it provides a "grippier" surface for the paint and tends to prevent paint lift-off when masking and such. 

For interior parts and minor bits (tires, etc) I typically use Tamiya primer. For the outside surface, I've fallen in love with Mr. Surfacer 1200.

That said...I just threw my can of Tamiya white primer in the trash a few days ago. I've been trying to use it to lay down a white undercoat for my yellow wing Wildcats, and from the can it was just ridiculously runny. Decanted and sprayed through the airbrush, it went all congealed and resulted in a night spent sanding both planes smooth again (and now I have to overspray white again to provide a base for the yellow...sigh). 

Scott,

I'm a long way from a highly experienced modeler, but I do always prime.  To me it provides a better base surface for the finish coats than just bare plastic. 

I have had very good luck using Kryon Fusion rattle cans, in either white or grey, for a primer.  It is cheaper than say, Tamiya primer, and so far I have no complaints.  Drys very quickly to.  IMHO.

Bob

Arespontus

One thing I noticed about using the primer is. If you make a mistake and you try dipping the part in Windex the primer will not come off but waterbased tamiya paints will come off. I figured this out on a model of a AH-64D.

Scott,

Are you referring to the  spray primer or the 40ml bottled Liquid Surface Primer?

The bottled primer is nominally a lacquer based product which will be unaffected by Windex, but it can be removed using denatured alcohol (but not Isopropyl). Note that Denatured alcohol will rip Tamiya acrylics off faster than Windex. 

I have been using this primer from Walmart (store branded)... it has been working great for me.  Best part it is very cheap as you can buy it for only $1.15 and it lasts for a long time unlike those Tamiya primers.  Maybe this helps if money has been an issue. 

But I recently bought Mr Surfacer 1200 and I can't wait to use it on my figures soon.

I used to use Tamiya's Primer before painting with Tamiya acrylics.  I read in one of Steve Zaloga's books the he doesn't.  I gave it a try not using primer and I saw no difference.  The only trick is to have a really clean surface before painting.  I even painted over photoetch without priming using Tamiya acrylics.  Once again, the paint adhered just fine.

-Jesse