wide86: ok when u ask this question, is impossible for anyone to answer. mebbe first u should understand the fundamental first. So i m not answering your question directly, but to tell u a little about primer/surfacer, n u will understand why i said so.
the purpose of primer:
1. to check mistakes or imperfection. there might be many uneven surfaces, either due to the process of manufacturing (plastic injection) or our mistakes (careless sanding marks, knife accidently cut or slice create some fine lines etc.) on the bare plastic itself, sometimes it's very hard to see. However, with the little bit of body plus the gray color, any small mistakes will be enhanced, or sometimes if it's small enough, been covered or corrected.
So, after u sand and such, u spray a layer of surfacer, let it dry, then, u check whether there's any flaw on the surface, before u applyt paint onto it.
2. To help the paint to "grab" onto the surface. Try drop a drop of water on your plastic, and u ll find the water will not stick onto the surface. paint tends to have strong holding power than water, but it does too tends to find ways to "escape" from the surface. Primer does have a little, just very little ability to melt plastic, hence, when u apply surfacer or primer onto the plastic, compared to water or paint, it holds on the the surface much stronger.
After u spray surfacer on, the next step is u apply paint on top. so this time your paint is not applied on top of a plastic anymore. instead, your paint will be sitting on top of surfacer/primer, which is much easier for your paint to hold on to.
3. consistency in base coat. This is a more complicated stuff for more experience modeler which i think is too hard for my limited volcabulary to explain
so i hope u get your answer.
QUOTE
if spraying wif out using surfacer will got wat effect ?
i think u should be able to find the answer.
Anyway, the idea of primer is long practised in art, many forms of art. however, it's only widely been use during the 90's for modeling. So even without primer/surfacer (like those great modelers in the 80's or even earlier), u can still make nice coloring. only problem is it's tougher and more tedious. primer is just a extra helper to ease our job in modeling. this is the reason why it's so popular in modern modeling until it has almost become a "must".
P/S: whatever, i say, the best way to find out is just use a small piece of plastic, and try out, with n without primer's effect. Happy modeling!