TOPIC:

Say I wanted to lay on a nice thick clear -- what's the best strategy? Do I put a few coats on and then wait to dry, then sand, and then apply additional coats, or should I put a bunch of coats on all at once, allowing proper flash time between them?

This go round I have now (re)painted my tank and fenders 3 times. Each time I screw up in new and inventive ways...but each time I'm getting closer to perfection...

Two coats base, two coats mid, two coats clear.

If you want a really nice smooth look I'd put down three medium coats, color sand to flatten any orange peel, then lay down two more coats. If you have graphics to add do that after color sanding. Assuming the last layers lay down smooth I typically don't cut the final clear other than maybe to remove any big dirt chunks. This approach assumes you are using real automotive paint. If using rattle cans all bets are off. Also, since you are in California I assume you are using low VOC paints which tend to have less solids than the older paints. If so you may need to add an additional coat.

Nessism wrote: If you want a really nice smooth look I'd put down three medium coats, color sand to flatten any orange peel, then lay down two more coats. If you have graphics to add do that after color sanding. Assuming the last layers lay down smooth I typically don't cut the final clear other than maybe to remove any big dirt chunks. This approach assumes you are using real automotive paint. If using rattle cans all bets are off. Also, since you are in California I assume you are using low VOC paints which tend to have less solids than the older paints. If so you may need to add an additional coat.

Ever had adhesion issues with this method? If you add additional coats of clear after drying and color sanding the first coats, you'd be relying on mechanical adhesion, versus with the first coats of clear I think there's supposed to be more of a chemical bond since they're supposed to go on soon after the base coat.

No adhesion issues. It's all applied within a week and a half so the paint is still receptive to the next layer.

P1010841 by nessism , on Flickr

Nessism's technique is what I do. Chemical cross-link is preferred but depending on the product the cross-link window is usually 24 hours or less for 2k clears. Secondary coats of clear have to rely on mechanical cross-link. use 800 grit and you will be fine. However the first layer of clear should always follow color coat immediately after recommended flash.

DoctoRot wrote: Nessism's technique is what I do. Chemical cross-link is preferred but depending on the product the cross-link window is usually 24 hours or less for 2k clears. Secondary coats of clear have to rely on mechanical cross-link. use 800 grit and you will be fine. However the first layer of clear should always follow color coat immediately after recommended flash.

Going off memory I think the "open time" for the Transtar epoxy primer I used was 3 days, but the base coat is only 24 hours. It tends to be a mad rush to get the primer on, sanded flat, color coat, and then some clear layers to seal it off. At that point you can relax a little. I use gray scotchbrite to flatten the clear and get the surface ready for graphics and the final clear layers.