G'Day Mate, nice car! OK, I've painted lots of cars, but only ever used a sealer once. Get some nice high build primer and spray a couple of wet coats, and see if you get a reaction. (anywhere) If you do, wait for it to dry, spray a coat of sealer over it, let that dry, then hit it with a few more coats of high build.
Spray a mist coat of a contrasting color (important, make sure that the contrasting color is compatible with the top coat, or you'll screw it up royally) over the whole shebang, then wet sand it back with 400-600 grit on a flexible rubber block(don't worry about the guys who'll say to use 1200-2000, they just wanna see your arms fall off) using a couple of drops of dishwashing detergent in the bucket as a wetting agent.
If you're left with any voids, low spots etc, the color of the contrasting mist coat will stay in those low areas. Use some more high build, or some "Spot Putty" (basically thickened primer that comes in a tube) to fill the low areas, let it dry, then rub it flat.
I don't know what paint you can buy in SF mate, I like "2 Pack" (not the dead rap artist) because you don't need much, (1 litre of base coat and a litre of clearcoat would do you whole Porsche) but if all you can buy to use at home is Acrylic lacquer, you'll need 2 litres of color and no clear if it's a straight color, or 2 litres of clear if you are using a metallic color.
When spraying, hold the gun around 10 inches from the work piece. (splay your fingers and thumb as far apart as you can on one hand, and that's the distance the gun should be from the work piece) Adjust the fan width on your gun to around 6-8 inches, and always start in the centre of the hood or trunk (gee I'm getting good at speaking American) and working out to the sides. If you can con one of your buddies to help and you can score 2 guns it'll go real quick, but no biggie if you can't, just work from the centre to one side, then work from that side right around the car.
I use plastic trash bags as tire covers so you don't get any overspray on the wheels and tires. Remove as much from the car as you can, and take the doors and any "swinging panels" off if you can, so you can get inside the door shuts, etc. Masking everything off is a PITA, but do it well and you'll thank yourself afterwards.
Lastly, you're painting it black, which is a great color for a Porsche, but remember, black shows up every ding, low spot, poor repair etc, so ensure that your preparation is perfect. The topcoat is only a reflection of your preparation. Make sure you familiarise yourself with prepwash, (wonderful stuff) and tack rags. Have fun! Cheers, Terry.
