As it is a friend s car i would like to help you solve it.
Orange peel roof.
This technique will be most appropriate if you have very large areas of damage or are applying a new orange peel texture to entire wall surfaces.
This is how i tackle an orange peel texture.
The end result is a beautiful flat ceiling.
An epdm rubber roof will also take on a chalky look.
One of the newest ways to repair textured walls and ceilings is with a gravity fed manually powered pressure sprayer.
If you want to totally get rid of orange peel you need to wet sand the car.
It s not hard but does take time and can be scary.
Apply the orange peel to the ceiling keeping the gun between 3 and 4 feet away from the ceiling at all times.
You may need a stepladder depending upon the ceiling height.
Every texture requires a different process to get smooth ceilings.
The clear coat on the roof came with a lot of orange peel.
You can test for vinyl by giving a pinch to the roof.
The after sales of the brand decided to do a sanding and polishing to remove however the orange peels continue the roof is entirely scratched and now some small marks have appeared.
Vinyl is also used for the roofs of campers and rvs.
Keep moving the gun.
Epdm is very smooth while tpo may be slightly bumpy similar to an orange peel.