Steve, parts that are painted will not glue together with liquid poly, this will damage the paint as you have discovered. Two things to do:

1. Scrape away the paint where the 2 parts are to join together, if you use liquid poly it may still run onto the paint so I would use Revell's Contacta glue which is on a needle type syringe.

2. You can use epoxy resin to glue the painted areas to each other. Epoxy resin is a 2 part glue/resin which you mix and then apply to the area.

It will damage the paint, but just put a small spot on the parts to be joined and you should be ok.
What Scania are you building and what parts are you trying to glue together?

Hi Steve,

As John said, you'll either need to scrape the paint away to expose the plastic, or use epoxy adhesive.

Have you painted the cab already? It sounds like it, so this advice will be for the next build. What I do is assemble as much of the kit as I can ... I work in sub-assemblies. For example, I build the chassis as one sub-assembly, the engine as another (if the engine will be a different colour to the chassis), the interior, and then the cab.

I base my sub-assemblies on the areas that will have the same base colour. Once they're mostly built, I paint them each as a unit.

For detail work (such as door handles, mirrors etc) I glue them on before painting the base colour and then carefully mask them off and hand paint them an appropriate colour.

Small parts can be attached using clear varnish instead of glue (less risk of damaging the paint).

For the windows etc, I either use PVA (wood) glue or epoxy.

Hope this helps, if you have any more questions, feel free to ask, and I'm sure someone will have an answer for you.

Bren

The comments about sticking painted parts together are very true. I've recently been asked to rebuild a model which fell off a shelf and shattered into pieces.

The Scania cab panels had been painted individually and then glued together, and the whole lot simply came apart as there was no bond between the joints, just paint.

Peter