what do you use primer for?

To prime a model for painting ... but also to check for gaps, flaws and things you didn´t notice when building.

Some paints wont spray or brush directly onto plastic .... they wont bite into the plastic .... and just run off, or gather in the crevices. Spraying with a primer, solves this problem. But do spray this outside and/or a well ventilated room as the fumes are quite strong.

Another reason primer is used, is when the kit is made from different colours of plastics and/or metals, etched brass, resin aftermarket items, etc. Firstly for the above reason and also it gives a uniform base for painting, meaning that all items will have the same starting base colour so can tie it all together better.

EDIT: Spray it on in a "misting" fashion .... not too close (and not on the same spot) to the model as paint build up will bury details. A good primer will "shrink" nicely when dry. Its better to spray a few very light coats than try to cover the whole model in one go.

ditto!

Just use good primer like Tamiya spray primer or Floquil spray figure primer that have fine pigments.

i saw in a pic there was a can of dupli color sandable primer in the background will that work too?

I use Automotive sand-able primer that car builders use. It covers metal and plastics well and bites well for a good hold. It also shrinks to fit and doesn't fill detail. If the kit has minimal photo etch or putty I may go right to the base coat.

Tom

For a primer on my kits I always use Gunze Mr Surfacer 1200 cut 50/50 with lacquer (cellulose) thinner. It works beautifully and makes a fantastic surface to paint on, especially for acrylics.

Cheers