Evening all,
I need some help on painting metal chains, tow cables and PE parts. I use enamel and acrylic paints but can't seem to get the base coat to stick that well. I always seem to get the odd brass or copper spot showing through.

Etch primer?

Any ideas are welcome.

Regards,

Heff33

Annealing brass with heat (a bbq lighter) will take the shine and coating off. Some etching solution might help, though you could end up dissolving your brass.

I have a couple of suggestions:
1) Before you cut parts off of the fret, soak it in vinegar for a couple of hours or overnight. It will slightly etch the parts, but the acid isn't strong enough to damage the parts. Rinse them well with clear water and dry them off, then proceed as normal.
2) Use a laquer-based primer on your brass parts. Again, you can do this before you cut parts off of the fret. The laquer-based primers tend to "bite" better on metal parts (at least for me).
3) I often take a sheet of 600 grit sand paper, lay it on a piece of glass, and swirl the whole PE sheet to scratch the flat surface of the parts. Again, I do this before I cut parts off of the fret, and clean it well to remove sanding dust residue.
4) Gunze has a primer available that is for metal parts. It smells a lot like nail polish and is clear. This seems to work pretty well, but isn't always easy to find.
Please note that if you prime the parts before you bend them, the primer will probably chip at the bends and need to be touched up. Be sure that there is no oil residue from your fingers on the parts when you paint them, as this will act as an excellent release agent for the paint!
Hope this helps.