This week on Sunday I sprayed Al's Heat and Noise reducer in the cab and engine bay. It was kind of tricky to apply. It is a latex elastomeric ceramic coating similar to the much more expensive Lizard Skin. The directions said to spray with the hopper/texture gun for best results, which I did. However the directions stated to do one thick coat at 31 mils, or 1/32nd (no thicker than 32 miles, or 1/16). I found this was was a bit thick and I had some runs. Perhaps I did not have enough practice with the gun.
The strange thing is that Lizard Skin says to do two light coats several hours apart to get the full 31-40mils. Al's HNR says to apply a second coat after 24 hours. According to that logic if you were to brush it on in multiple light coats it would take several days.
Fortunately the day I sprayed it was in the 70s, and at night it was in the 50s. The next day it was 85F, and I brushed the Al's HNR on the engine bay side panels. Brushing was tricky. It was hard to lay it on as thick in one coat as with spraying. I did not want to wait 24 hours between coats so I brushed it thick, and I ended up with some runs, thick spots, and brush streaks. The thicker spots in the coating ended up skinning over and shrinking, leaving rifts in the coating. Peeling was not an issue.
I ran two (later just one) box fans in the cab, and two small fans in the engine bay to aid drying. Today since it has been a few days drying I decided to sand the runs out of the hnr coating. To level out imperfections, I sprayed a light coat in the cab and under hood, then brushed the side panels. The light coat dried much faster and hid some of the defects. It was in the 50s while I was spraying. I should be ready to spray the green tinted Al's Liner this Sunday.
If I were to do it again, I would spray/brush on two light coats several hours apart after testing this method. If I did not test, I would spray/brush two light coats, waiting 24 hours like the directions say. I would make sure it is at least in the 70s for several days and dry, even though the directions say it can be applied above 40F. A shutz gun might work in the engine bay since it is smaller than the hopper gun.
Overall it took two gallons to coat the cab, doors, hood, and side panels.
I am happy with the product. It really took the ring out of the metal when you bang it. It has a duller sound now. I do not know how good the adhesion is. I can did my finger nails into it and pull chunks up with effort. I made sure to properly sand the old paint though before applying. I can even pull chunks off on areas with a rough base coat. I don't know if this is due to it being applied too thick, or just the nature of elastomeric latex coatings.
The softness does not bother me, as it will be top coated with Al's Liner like recommended, however I am worried about possible lifting of the liner/hnr. Only time will tell.