Is this suitable to use over powder coated aluminium windows? Or is an etch primer and duramax better? (Or is it not suitable to paint over powder coated frames?). Thanks!!
Etch primers are used to key metal surfaces allowing the paint to stick to them. As your windows have been powder coated there is no exposed metal for the etch primer to work on.
It would be my recommendation to use the Dulux Metalshield range as no primer is required and they are an epoxy enamel paint which is hard-wearing. Make sure you clean all the painted surfaces down with sugar soap and rinse clean afterwards before applying the paint.
Please let me know if you need further assistance or had questions.