Delta Ceramcote paint is meant to be used on porous surfaces, such as wood. Plastic is non-porous and therefore will not take the Delta stuff permanently. It can be used over other paints, just not on bare plastic.
For models I use this stuff mainly for drybrushing and specifically for groundwork. I also use it for other things, reproduction squadron patches on wood and leather and such as well as on bases for models. But on models themselves, I use it very rarely.
If you do have a use for this stuff, look for a sale at some of the bigger craft stores in your area. We have Michael's here in WNY and you can often times pick a bunch of this stuff up for around 50 cents a bottle.
Fade to Black...