Priming Primer?

Hmmm, well, I put Gesso on Super Sculpey and then sand it up all nice. I'm a beginner, so I've only ever worked on Super Sculpey, but it looks pretty good.
Primer gives you a nice clean foundation to work on and helps get rid of little nicks and imperfections. I've read that resin picks up every little imperfection in the surface of a sculpt so this is why it's a good idea to use a primer to even things out. Also, if you're not intending to do a resin cast, primer makes it easier for you to paint your doll, I believe.

I use the brush on kind of Gesso. Looks just like white paint. But it does come in a spray.

Man, I'm a beginner too though, so maybe you shoul;d wait for someone experienced to say something, ahahah.

Hope this helps.

 

I'm no expert, but primer firstly makes all the subtle scratches and unevenness and flaws in your sculpt more visible, so that you can work on sanding them back and making everything smooth. Therefore primer is something you do in stages. As you sand back you will inevitably remove some of the primer, so it gets resprayed so you can see if you've got all the kinks out. It is very soft, so you sand it with a fine sandpaper (400 grit) and it makes the surface very smooth. Primer does fill small scratches, but you still need to sand it. When you've finally got everything smooth, the last coat of primer gives you a nice dull testure, instead of the shinyness that you may get if just sanding.

Some materials like paperclay have to be be primed if you are pulling molds from them... any porous material needs to be primed, but for a professional surface finish any sculpting material would benefit from it. It sure is frustrating to spray your parts in grey and find all these little nicks and things that you couldn't see because of the colour of the clay, but it would be even worse to see these issues for the first time when you pull the first casts from your mold.

I get my b/f to do all the spraying for me because he's got a lot of experience handling the spraying equipment (from working on his cars), I want to learn, but I don't want to mess up the current sculpt with my newbieness. We use CarMaster Acrylic Primer/Filler and it is applied with a spraygun hooked up to a compressor. An airbrush would also work, but Ron gets better results with the spraygun. We also use lots of acrylic thinner to get the viscosity of the primer nice and low, which makes it easier to apply.

The surfaces are pre-sanded up to 120 grit, which is a bit rough, but gives the primer a good grip, otherwise it might just peel off. All the sanding after spraying is with 400 grit, and I use the wet/dry type sandpaper, but I use it dry. I wear a respirator when sanding because I've been getting sinus irritation when I don't. I use a rag to wipe off the dust as I go. After sanding and before re-primering I also wipe down all the pieces with a grease and wax premover (prepwash or prepsol) to remove dust and fingerprints that might prevent the primer from sticking properly.