Re: Plastics on Chevrolet Avalanche
Welcome to Wax Forum, and thank you very much for sharing your experience -- that's impressive!
The Avalanche body cladding has been problematic for many owners, and it is complicated by different years having different protective finishes, all of which seem to age differently and respond to restorative products differently.
One thing that can get in the way of Back-to-Black working properly is that in your model year there is a coating that oxidizes, and likely pressure washing got rid of it and allowed the Back-to-Black to do its job.
In general, dirt in the textured coating of any surface can also prevent Back-to-Black (or any trim restoration product for that matter) from doing its job.
We'll certainly agree that it sounds like your idea of pressure washing was the key to optimal results in this case.