wash photoetched parts?

You will also either need ot prime them or soak them in vinegar for a few hours to get the paint to stick better.

For parts that need to be bend I recommend to anneal them.

I actually haven't done anything to my PE parts, and the paint is adhering to themt just fine. Of course i am uusing enamels, if you are using acrylics you could have more of a tought ime.

Just dunk the PE parts in some alcohol for a few seconds and then lay them out to dry. The alcohol will remove any grease on them.

I use acrylic frequently on PE and haven't had any problems with it peeling or coming loose, but then I've never had the nerve to try masking it either. Acrylics work fine on PE that has to bend because they appear to me to be more flexible than enamels.