painting in the cold

Hi dave, yes painting in the cold is not ideal because the paint can draw in moisture,
but no paint is probabley werse.don't leave in primer either as it is porous.
On a safty point, gas heaters have a flame? ALL solvent based paint is HIGHLY FLAMABLE so must be treated with care , have you thought of using a electric infer red patio heater they only heat the object not the air around it.

Half an hour isnt going to do anything, you might as well not bother.
You need to bring up the tempreture of the actual metal not just the air tempreture. A better idea, if its possible, would be to leave the heater on all night the night before to get it nice and toasty. Turn it off while your painting and while the paint flashes off because a space heater will blow curse word everywhere, right into your new paint. Then turn it back on while the paint cures.

The way works going on my escort at the moment i think i'm going to be looking at painting it in the coldest part of the winter. What i'm planning on doing is build a tent over the car out of bubble wrap, perhaps two or three layers over a metal frame and sealing it up to keep the heat in and the dust out and running a pipe to the extractor and building a filter box to stop any dust getting sucked in. It'll also create a smaller space to heat up.
You can rent industrial IR heaters and if your only going to need one for a weekend that's probably be a better bet.

I don't know if its a good idea leaving it a week between primer and top coats either, especialy in cold damp weather. Primer soaks up moisture like a sponge and it'll show up under the topcoat, also if you exceed the recoat window you can have adhesion problem and could find you new paint starts flaking off after a few weeks. If youve done all the prep work properly i don't see no reason why you cant get it done in a weekend. Or if thats out of the question try getting the shell done one weekend then doing all the removable panels the next.