Regular paint vs primer

[Len Colombo]

Asked this on another board but did not get a response. Can you use regular flat white or grey paint as a primer? Or does primer have ingredients in it that regular paint does not have? Tia.

[Snake45]

I've used many of the Model Master military flats as primers, everything from white to dark blues and greens (airbrushed). They perform most of the important functions of "primer" just fine (though they might not stand up to the hotter automotive paints).

"Back in the Day," many, many of us used AMT, Testor, or Pactra Flat White as a standard "primer" under just about every color. It worked fine.

[Warren D]

I have run across a few brands that do have a somewhat different primer.  Hobby paint called Tru-Color is that way, they say to use their primer and you really have to.  Learned that lesson the hard way.  If you are painting fiberglass or aluminum then the primer is more specific to the material.

[astroracer]

  On 9/28/2016 at 8:20 PM, Len Colombo said:

Asked this on another board but did not get a response. Can you use regular flat white or grey paint as a primer? Or does primer have ingredients in it that regular paint does not have? Tia.

"Regular" paint, even if it is flat, has a different composition then "primer". Primer is meant to fill imperfections and be sandable so it has more solid material in it.  A couple of coats of primer/surfacer will sand down MUCH better then a couple of coats of top coat intended paint. The primer allows you to sand it down, not only to level surfaces but to cover body work and feather-edge body worked areas. Regular paint is not intended for that purpose.

Mark

Edited September 29, 2016 by astroracer

[yh70]

i been using flat white and gray's for years and never had any problems.most are Walmart brands..

[Snake45]

  On 9/29/2016 at 3:29 PM, astroracer said:

"Regular" paint, even if it is flat, has a different composition then "primer". Primer is meant to fill imperfections and be sandable so it has more solid material in it.  A couple of coats of primer/surfacer will sand down MUCH better then a couple of coats of top coat intended paint. The primer allows you to sand it down, not only to level surfaces but to cover body work and feather-edge body worked areas. Regular paint is not intended for that purpose.

Mark

Can't argue with any of that, but I've found that for 95% or more of the stuff I do, a true "primer" isn't really necessary. I don't do a lot of heavy bodywork with putties, fillers, dissimilar materials, and so forth. I'm mostly just laying hobby-grade enamels or lacquers on lightly massaged kit styrene, and for that, flat paints work fine. Most of the time they don't even require sanding, and they don't obscure detail as much as heavy-duty primers.