PPG Primer Surfacer, Shrink time? Options

[bbrock]

This is a pretty specific question but wondering if anyone has experience or thoughts on PPG K36 vs. K38 primer surfacers. In reading other forums, it seems some people think that because K38 is a high build surfacer, it has a higher solids content and therefore less shrink back. Local shop stocks K36 but has to order K38 which is also more expensive.

Would one month sitting in the sun be enough time for either of these to shrink before blocking, seal, and finish coat?

I realize there are probably cheaper options that are just as good but I'm pretty limited on what is available at the local paint shop and want to keep all the products in the same paint family since I'm a novice at this.

TIA.

[Mark Henry]

High build primer surfacer should never be used as/like a bondo, the thicker the primer is in an area the more issues you will have with shrinkage. The filler work should be as close as possible to the finished surface, all pinholes filled, etc.
Only then should the high build primer surfacer be used for final block sanding..

[twistedstang]

High build primer surfacer should never be used as/like a bondo, the thicker the primer is in an area the more issues you will have with shrinkage. The filler work should be as close as possible to the finished surface, all pinholes filled, etc.
Only then should the high build primer surfacer be used for final block sanding..

This. This right here. If you arent sanding 90% of it off, you're not using it right.