The process for colour changing aluminium door & window frames is faily simple, unless you are repairing any damage or there is bare aluminium showing you wont need to use a primer,

‘If there is any aluminium showing an etch primer should be used as most paints wont stick directly to aluminium’

Simply use a red scotch cloth to provide a key onto the frame, this will leave a dull lightly scratched surface,

You will then want to degrease the frame and use a tack rag to remove anything that will effect the paint adhering to the frame,

Then simply apply 2/3 coats in different directions to ensure you get the paint everywhere it needs to be, Leave the frame around ten minutes between coats and a couple of hours before touching or handling it.