Sugar soap or sandpaper

No, it doesn't. Sugar soap cleans the paint and gets rid of grease etc, whereas sandpaper levels irregularities and gives the next coat a key to help it to stick. Ideally you should sugar soap then sandpaper but there's not much point in sugar soaping if the paint is clean..

Rob Graham

Thanks Rob Looks like it is the sandpaper,there are small panels in the door so a bit of a pain to do

In article , Tab writes

I've done many panelled doors and wrapping a right sized piece of the paper round a small block of wood helps get into the difficult bits. Off cuts of planed batten (say19x38x100) and window bead off cuts. Edges or rounded edges clean up mouldings nicely. I use 80 grade paper for almost everything but 120 grade might suit you better.

A bit of fine steel wool might solve any mouldings problem.