HOW OLD IS THE PRIMER AND CATALYST.
i don't care what you have done in the past. you have never had this problem in the past so what happened in the past doesn't matter now.


the data sheet says pot life in 1.5 hours, not 5 min, so something is wrong with the product or the temp you are using it in is to high for the catalyst. i know PPG K36 primer the heat can kick it to jell fast also. you might have to spray in lower temps to get it to work.

if the heat is causing the product to gel you don't need to wait 5 min between coats. re-coat immediately after flash off.
or you could add a little retarder to slow it down some.
or use the slower catalyst, the extended cure times of the other catalyst is longer is because it is designed to be used in higher temps.

the gun tip size shouldn't make a lot of difference. the data sheet says 1.5-1.7 tip. if the tip is to small it will just spray really dry.

https://www.coatingsmall.com/cap_data_do...LH810_LH820.pdf