Set Backs - Under coating

I decided to use Mastercoat product line as a primer, surfacer and sealer. As mentioned previously I used POR15 on the frame to mitigate rust but the product PREP is enormous! Even though I had the frame off and all parts off from the frame believe me its a lot of work. Mastercoat prep is easier, here's the process..

Step 1: Metal Prep and Rust Remover, this product is an acidic solution and is a thick fluid, not a gel but close. Simply wipe it on the prepped surface rust, leave on about 30 minutes to remove heavy rust (keep it wet) and wipe off with a wet rag that is saturated with metal prep. If heavy rust exists use a scotch brite and work the metal prep into the rusty surface and wipe off with wet rag saturated with metal prep. You don't need to wash off the metal prep with water or neutralize it. The treated surface can sit for up to a year in this condition without rust returning.

Step 2: Now you can spray, roll on or brush on the rust sealer. It is silver in color and lays great, use 2 coats if your going to follow up with a topcoat or 3 coats if no topcoat.

Step 3: I used Mastercoats gloss black (ag111) topcoat and sprayed the product which can also be rolled or brushed on. 

I sprayed these coatings on the entire underside  and firewall of the car (see Undercoating page), it looked great!  shortly after I got done with the underside of the car I placed another order of Mastercoat to spray the inside of the front fenders, both sides of the front wheel wells, gas tank and a lot of smaller brackets and parts like the battery tray etc.... When the product finally came and I was mixing the silver primer I noticed it was totally different than the product I used on the first spray. It was a lot thicker even after I added the mastercoat thinner, also it didn't seem to mix well with the thinner almost like adding water and oil. I called the owner of the product line (who I got to know from past calls to the company) and explained what was going on, he said to add an additional 10% mineral spirits (on top of the 10% I had already added of their proprietary thinner). The product was now thin enough to spray with a 2.0 tip but still pretty thick. Once I got the two primer coats on I sprayed on the black topcoat, by this time it was mid afternoon.  As I was spraying all of these parts I followed the same process I used to spray the underside of the car. That evening I went out to the shop and checked the status of the parts and all looked great. No runs or missed areas and the product was dry to the touch and smooth (it was still soft but didn't smudge touching it). 

The next morning I checked the parts and everything was a total disaster. Not a single inch of the sprayed surfaces was smooth but felt like sandpaper, expand the  pictures below to see what I saw. I emailed these pics to Pat at Mastercoat and he was shocked, had no idea what could have caused it. Pat said he would send me another quart of topcoat and I should scuff down all of the painted areas and respray. 

This is a major set back since sanding all of these sprayed parts down will take a significant amount of time. I am hoping that when I prep and paint the entire inside of the car and trunk that it finishes the same as the undercarriage. Even though these inside areas will be covered and never seen I really  want them to be smooth and no texture.