The TrueLine CNR and CPR cabooses came with end railings and ladders and platforms done in engineering plastic, but the colour was noticeably different from that of the paint applied to the rest of the car.I read somewhere that Tamiya paint (brush-on version, not the spray can stuff) sticks reasonably-well to such plastic. The idea is to paint the object with Tamiya (any colour, although something at least somewhat similar to what you want for the finished colour might be a good idea), then let it cure for at least 24 hours, before brush-painting it with a water-based paint in a colour you feel matches the rest of the car.
I can't find any "before" photos, despite doing 6 or 7 of these for a friend and for myself, but the original end details were in the same colour-group as the rest of the car, but definitely were not the same colour. Because they were unpainted, they looked plastic-like and appeared almost translucent on their surface.I tried the Tamiya version and then mixed Pollyscale paint to match, as best I could, the rest of the carbody on this ex-CPR van....
...and likewise for these CNR cars...
The paint has stood-up well, with no chipping or flaking, but cabooses don't get handled all that much on my layout or that of my friend.I've also read of others using Pactra (Testors) "Racing Finish" for R/C cars, and did use it for the yellow end railings on the Grand River Southern car. It too, has stood-up well, but gets little handling.
Wayne
I haven't found ANY that adhere well but I've found that light coats of Krylon gray or red oxide primer seem to hold pretty well. They don't flake off but will eventually rub off with frequent handling. Others have used automotive primers for plastic parts, such as bumpers, but I haven't tried any of these.
I did a comparison for one of the forum members here a while back. He was interested in the "Fusion" paints which are supposed to be specifically made for plastic. Those didn't stick any better.
IMG_4218_zpsod02epc3 by Edmund, on Flickr
These parts were cleaned and degreased before painting. The "Fusion" paints are very thick, IMHO.
IMG_4243_zpsb8beoatm by Edmund, on Flickr
Try the Krylon red oxide primer in a light coat then spray your Chinese Red.
Good Luck, Ed
Here's a thread that works its way through the years to the present, with some good advise and techniques on painting acetal ( delrin) plastic.
http://cs.trains.com/mrr/f/88/t/162952.aspx
Check it out.
Mike.
My You Tube
The title says it all. What paints out there can cover acetal plastics? If posible, I would like a color that is close to CB & Q Chinese red. As usual, any assistance that can be provided would be most welcomed.