I wanted to get some advice on painting the above - Would I be good to sand them down with say 400 grit sand paper and then spray them using something like PlastiKote? Should I prime them first?
Depending on the factory finish, I tend to just give the rads a light sand at 320 then 500 grit (as in a really quick pass just to roughen up the paint/powder coat and remove any lumps) then prime. A couple coats of primer does the trick and doesn't take long, then just a few coats of a paint of your choice, that should work fine. I use painters tape to mask off the fins, takes only a few minutes to do, even better if you have rads with a removable core.
Hmm, tbh my suggestion is don't. Acetal just has really poor painting qualities. If you scuff it up a bit with a medium grit paper and prime it you may be okay but don't quote me on that. I'd reccommend vinyl wrapping it with the seams on the backside but there are probably too many bevels to make that look good.
Thanks Maki, that's much appreciated. It sounds like I'm best off maybe rethinking my plans then and leaving that black or swapping over to a res which is already white
As discussed, the res top and bottom are made from POM Acetal, which won't take paint. The reason is that the acetal has very high chemical resistance and low coefficient of friction. All good properties to have for water cooling equipment. DuPont developed a process using chromic acid for surface etching, in perpetration for gluing (but will also work for painting). But this is not a process for a DIY project (unless you have access to a proper chemistry laboratory, even then not advisable). Since the the process is chemically altering the surface in order to create a bondable surface I am not sure how well sanding will work. I made the mistake once when I got some parts for a project cut from Acetal, selected because it was available in opaque black. When I received them I was unable to solvent weld them together. I could use epoxy but the bond wasn't strong enough. If the case is a show piece, once assembled won't be touched, you might give it a try just be aware it will be fragile. If it is for your use and you'll be in and out of the case then I would not bother.
I have painted an EK rez a few times, as long as you scuff it up and do it last (so it doesn't scratch) it work. It can be scratched off though. It isn't 'oh meh gurd I sneezed on the rez and all the paint flew off it' fragile, but it isn't as strong as on other materials.
