Primer help please!!!!!!

[flygilmore]

I am starting a 1/72 Fokker Dr1 and had to get rid of that yucky red plastic.  I am going to be both airbrushing and brushing MM enamel paints on this model.  On Sat. evening around 9pm. I gave two light coats of Testors enamel primer (gray) out of a spray can onto both sprues.  Before doing the primer, I sprayed 91% Alcohol onto the sprues and wiped them dry then used my heat gun to further dry any tiny crevices. No runs, puddles etc. and it covered very well with pleasing results.
While the parts look and at first touch feel dry/cured, as of last night, I could still take a fingernail and pretty easily scrape the primer off the plastic and if I held the sprues in one spot for a while, I could feel some gumminess and it would leave some gray on my fingers. I read somewhere that the alcohol I used could be preventing the primer from curing completely or does it take 36-72hrs. like other enamels to fully cure?
I am a newbie and haven't built a models since I was a kid so have a lot to learn.

Thanks!!

[uncletony]

I'm not a chemist, but I can't see how washing the plastic with isopropyl would inhibit the enamel primer from curing. Give it a few days...

[Des]

The only thing I can think off is that the spray can was not shaken enough before use, apart from that there is no reason for the paint not to dry in the usual time frame.

Des.

[Ian from Doncaster]

I use a plastic primer from a rattle tin from the auto store (in the UK Halfords is a nationwide chain) which dries in about 10 minutes.  It can be a bit rough, but nothing a smoothing off with micromesh won't fix.

[kornbeef]

Tamiya for me. seems to cover nice and thin.

[uncletony]

Tamiya for me. seems to cover nice and thin.

Me too. It comes in an extra fine grade too.

[flygilmore]

Well, went ahead and ordered a Tamiya fine surface primer in a rattle can.  Hopefully I will be really pleased with it.

Thanks.

[uncletony]

I think you will. Here's a tip: heat the can by soaking it in hot water (not boiling, but good n' hot, 140F or so ) for a few minutes before you use it. Obviously keep water out of the nozzle area. A pint sized glass works pretty well.

The heated paint will spray more finely.

[Ian from Doncaster]

I think that is a good tip for any rattle tin, the paint seems to flow better when warm

[uncletony]

I think that is a good tip for any rattle tin, the paint seems to flow better when warm

yes indeed applies even to painting your lawn furniture

[Ernie]

My primer if choice is Tamiya fine in a rattle-can.  Extremely smooth and
easy to use.  Best to use outdoors, if you can.

Cheers,
Ernie

[treadhead1944]

Humidity and air temperature can play a big role in paint curing. Colder weather can slow down the evaporation of the solvent, creating the situation you are experiencing.

[ALBATROS1234]

i gotta give another thumbs up on the tamiya fine surface primer in the rattle can, i use this for a prime after its built and ready to paint this gives you a uniform base to work with. i always prime photoetch with it too. some applications i use auto primer, either filler or sandable mainly for scratching wings and such.