I wasn’t sure where to post this so I figured this would work.
I’m having somewhat of a problem that I’m sure everyone has seen. The model I’m building has had some pretty nasty areas that have needed filler and primer. Generally, I fill the area, sand, then prime. I use whatver paint I have for primer. In this case, a mixed color of MM paints that is a brown color. Anyway, I then sand and prime again. I keep doing this until the area is flaw free.
Here’s the problem. Anywhere I’ve sanded is much smoother than the surrounding area…usually right along where the seam was. I guess the paint has some texture and I’m getting rid of some of that by sanding. When I prime over it again, it’s still there. With flat paints, that area is quite noticable. I’ve looked back at some of the last few I’ve built and most all exhibit the same thing. I could just keep spraying primer until it’s gone, but I don’t want 5 coats of paint down before I even put down my topcoat.
Sounds as if your primer is soaking into the putty, which will give the puttied surface a different texture than the plastic next to it. I used to use a putty that did this to and I ended up using a gloss paint (usually white) as a primer - it didn’t seem to soak in quite as much as a regular or flat primer - sanded it with 800 or finer sandpaper. I guess what I’m trying to say is the gloss paint worked more as a sealer than a primer - and as long as you have scratched the surface, any following coats should adhere.
You can use any paint as a primer. But paints that are intended for priming often contain talcum to fill small irregulairties. You might want to try a “real” primer, such as tamiya primer.
A true primer is what you need. Primer is a different formula then a paint that you would use as a top coat. Primer is formulated to seal the surface in such a way that your finish coat will be consistent and smooth. Who ever said you can use any paint for a primer is wrong. Use a real primer and you won’t have any problems.
Use Mr. Surfacer 1000 or 1200 as your primer but also take a good look at that seam. Are you sure that you have not created a slight flat spot and this is what you are seeing?
Positive. I think these guys are right. I think the paint is reacting differently to the filler. I swiped some filler on some scrap plastic and painted it. It exhibits the same thing. I guess an actual primer is the answer.
Do any of you guys use regular automotive primer for this? It seems like I have in the past but I can’t recall why I got away from it. I know I was spraying into a jar then spraying it on the model with my airbrush.