Garden Railway Forum

A similar trick from my 4mm days was to use Rizla cigarette papers. Spray one the colour you want for the lining background, then draw a line across it in the central colour using a bow pen or Rotring pen. Then use a fresh scapel blade to cut as close as you want either side of the line and hey presto you have, say, a black line with two white borders. The cig paper will stick to the weted model surface and can be manouvered to the right location with a fine paint brush and will follow fairly tight corners. When it dries out a quick squirt of varnish will seal it in place.

gregh wrote: Tue Dec 29, 2020 9:47 pm I've never thought of painting decal plastic. Do you prepare the surface in any way?
(I have painted other sheet plastic but always rub it with fine sandpaper first to give the paint something to grip)

No, the clear coating on blank waterslide decal (transfer) paper takes enamel paints nicely. I wouldn't use acrylic paints on a bet though, so I've no experience with them.

I normally don't do any surface sanding on polystyrene and ABS, or use a primer. The only time I've used primer on a plastic recently was when I painted the sleepers before laying the track in the garden. They were moulded in either polyethylene or polypropylene and I used plastic car bumper primer so the paint would stick. It's lasted out in the weather for two years so far....

Graeme

GTB wrote: Wed Dec 30, 2020 12:02 pm
No, the clear coating on blank waterslide decal (transfer) paper takes enamel paints nicely. I wouldn't use acrylic paints on a bet though, so I've no experience with them.
I normally don't do any surface sanding on polystyrene and ABS, or use a primer. The only time I've used primer on a plastic recently was when I painted the sleepers before laying the track in the garden. They were moulded in either polyethylene or polypropylene and I used plastic car bumper primer so the paint would stick. It's lasted out in the weather for two years so far....
Graeme

Very interesting that you don't 'sand' styrene. I usually use 'scotchbright' on styrene before painting, then wash.
I can almost guarantee the spray enamel I use will craze with no primer, and may still craze when primer used.

gregh wrote: Fri Jan 01, 2021 2:41 am Very interesting that you don't 'sand' styrene. I usually use 'scotchbright' on styrene before painting, then wash.
I can almost guarantee the spray enamel I use will craze with no primer, and may still craze when primer used.

Hmmmm, I wonder........

I do all my model painting with an airbrush and enamels and I've never seen any crazing on either injection moulded kits, or polystyrene sheet. Even back in the ‘80s when I used Floquil I had few issues, although being a lacquer that had a reputation for attacking polystyrene.

However, I've never used aerosol paints on models. With aerosol cans, there's little control of application rate and no choice in the thinner used, so I guess the risk of solvent attack on the primer, or the base plastic, would be higher.

I degrease polystyrene before painting with detergent and an old toothbrush, but that's all.

Graeme