Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

My guess is the finish to the spray is way too smooth.

A bit of "tooth" would allow the fairly thick paint to have something to grip onto and spread around (smear) rather than slide, that is why most painting surfaces are prepared with "gesso".
A tiny bit of a powdery or uneven surface also helps break surface tension and allows the paint to wick over the surface.
I would suggest using a thin layer of "proper" primer first, then apply the GW base coat which really is more a paint rather than primer.

Inverting and shaking hard the paint and/or primer to ensure it is well mixed will be important about 2-5 minutes if it had been sitting around for an extended time... however you do that.
You may not have an even mix coming out: too much solvent or too much pigment.
Also make sure it is at room temperature (keep in the house) prior to spray as well as the model (especially metal ones).

One other thing is that the surface may have been contaminated by handling or some overspray of some kind, try giving it a wash with a scrub with a brush (it may score up the primer too which would help).

If desperate, Liquitex or some other company's "flow-aid" could be used to help reduce surface tension and allow the paint to level out better.

 skchsan wrote:
Seconding primer. It seems like the can wasn't shaken enough or sprayed too close. Or sinply bad batch of spray.
You might actually benefit from spraying too far at this point so that you gain a bit of grainy texture for the paint to bite onto.

Good thought!
I have suffered from too much distance or humid air and get the "fuzzy" model so go easy on this but paint partially drying before hitting the model will give a more grainy surface which may be needed.