First few pics are during the process. Last pic is the product I use.
-First you want to push in on the dash, the brittle, cracked pieces will crack even more. I peal off all of the broken pieces and peal it back (kinda like opening a hard boiled egg) until it is somewhat flexible and stops being brittle.
-Next step is to start applying the polyvance padded dash filler. This is pretty much the same as doing body filler. Its expensive so you dont want to waste any. I mix up about the size of a quarter at a time, making sure I have no waste. Will need many coats to build it up, but it dries pretty fast.
-Between coats I use a surform plane (kinda like a drywall rasp) and knock the high spots off between coats. This makes the final sanding a bit easier.
-Start sanding with coarse, 80gr when it starts getting close to the finish product, on the final coats I sand up to 220-320gr. The filler sands very nice and will feather out.
-I use a fibreglass drywall tape (a woven material, not the web like stuff) at the 'cold joints'. I have done with and without both ways successful, I used the tape on the last couple just to see how it would work.
-Once sanded I used the SEM texture coating, hold the can at least a foot away and kinda dust it on for a better texture. A couple of light coats. Wont be factory texture but it doesnt look bad.
-Paint (dye) over the texture coating with your colour choice SEM int. dye spray.
-Use Sem low lustre clear as the final coat.
