I ended up going back to the 16mm scale, new engine purchase

[artfull dodger]

Yep, Roundhouse uses 2 stage as we call it here in the states, automotive grade paint for their engines. The secret is the hardener that is mixed in when preparing the paint before spraying it. That is what makes the paint very durable and less prone to chipping and scratching with normal use.

 

[Paul M]

The secret is the hardener that is mixed in when preparing the paint

I always wondered how they made the paint so hard. I've seem engines take a dive onto concrete but not suffer a scratch. ( Don't experiment please, it's not a good idea)