Preparing Injection Moulded Plastic for Painting

How to do it, advice sought and offered.
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Posts: 107
Joined: Fri Mar 06, 2015 11:11 am

Preparing Injection Moulded Plastic for Painting

Post by theparley »

I have just used Precision Paints Super Pre Paint Cleaner PQ19 on an injection plastic model. There were no instructions, so I brushed it on and allowed it to dry (which it does rapidly). I find the results disappointing. With brush applied acrylic paints, the brush slides over the surface, failing to leaving sufficient paint behind. I fared little better with enamel paints. There are two questions therefore:
(1) What did I do wrong ?
(2) What method or application do you employ ?
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Joined: Fri Apr 18, 2014 7:28 am

Re: Preparing Injection Moulded Plastic for Painting

Post by LarryC »

If you are talking about plastic kits for rolling stock, I wash them in a solution of washing up liquid and scrub with an old toothbrush, dry off with a kitchen towel and then leave them in the oven at 50' for five minutes or so. I then use a spray primer from Halfords, B & Q or similar. Grey, white or red oxide do the job nicely.

If you are talking about plastic moulded figures such as Airfix or Preiser, the situation is more complex as the plastic is notoriously difficult to get paint to adhere to. (One reason why wargamers, despite the higher cost, prefer metal figures.) These should be prepared as above. What I then use is a primer/undercoat from Army Painter: these cost between £8.00 and £10.00, depending on retailer and type, and come as white, black and others. For figures, which to use depends on your painting technique. I use black undercoat and leave eyes and mouth unpainted when I put on flesh colour(s). I build up the shades by adding the same colour with (more) white added for highlights. The alternative is to use a white undercoat, and when the shades are applied the paint gravitates to the folds, giving deeper, darker hues and the highlights appear naturally. A wash with dilute black (or a commercial product) settles in the folds to reinforce the contrasts.

Plastic figures need to be varnished or the paint will flake off if they are bent (or even dropped). Again, Army Painter products help; I use their Satin varnish to help fix the paint. I use it on both figures and rolling stock - it is perfect for coaches. A matt varnish is better for goods stock.
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