Hey gmckustom I also use ppg and this is a tough one . your rep is right the ncp 271 is a direct to metal primer sealer,I know you don't want to here this but start over now because this little baby will keep haunting you,there are two things that we need to know did you sand after you blasted and what kind of metal prep did you use.I personally have never used metal prep and have never had primer crack or peal,are you reducing yor primer,if your not and you put more than two wet coats and dont't cure it ,it will shrink cracking will happen if the material is to thick and ncp isn't much of a high build k38 over ncp is how I do it. so it still cracked once it was stripped again , it can only be one or all of these three things the metal prep the primer is on to thick or a bad batch of ncp 271 that has happened to me when I lived in a cold area take two pieces of scrap sheet metal use metal prep on one and not the other then prime see what happens then try with reduce and non reduce . I am really leaning towords the metal prep did you wipe it off or is it the kind that stays on and you really have to pour it on to make it crack I mean like actually pour it! and well if it is a bad batch then ppg can pay for all your heartache and frustration. but my recomendation is still start from the bottem again because whatever it is is still there and it wont go away until you find out what it is and make it go away ! hope this helps and send me some pics of the problem if you could keep me posted.
