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.

[roblav1]

It was definitely easier spraying lacquer back in the day... more forgiving.

On the K36, I start with 180 or 220 dry in an orbital and/or straight line sander, just to get it somewhat smooth... because K36 is a lot harder than the old lacquer primer surfacer. Then I wet block sand with 220, then 400, then 600. K36 will actually sheen a bit with 600 wet. K36 spec sheet says 4 hours to sand after spray.

I found that using no reducer in the first coats is OK. But highly recommend a 5:1:1 ratio with reducer on final K36 coats. It was less splotchy when I tried my old siphon gun once, but overspray was pretty bad. So I reverted back to the HVLP.

The reason I use black DP90LF is that I can see it easier if I start to sand through the K36. And I also use the DP90LF on almost everything on the car that should be black... like suspension, rockers, engine lid, etc.

Today is sanding day on the hoods, engine lid, and eyebrows... with a small bit of filler here and there. Good luck!