I am posting this method of creating painted decals using cling wrap and school glue here, as well as in the Builders Workshop and Foamies (Scratchbuilt) sections as new threads, since I could find no other reference to a similar method in these threads or elsewhere. Although the method describes roundels, this method could also be used for any other shape that can be cut out with a knife or compasses, possibly using a template – German crosses or banded tricolours are a good example. I found these to not work very well when using water slide printer paper, as the printing often bled and very thin shapes were impossible to slide.
When I recently received my Durafly SE5a, it had rather horrible wrinkles in the roundel decals, particularly on the upper wing. I don't know if mine were unusually bad or this was just normal, but to me they detracted from an otherwise beautiful plane. I tried removing them with a covering iron without much success, and if I had turned the temperature up any higher I would have got the dreaded alligator skin.
I did a bit of a search for how to airbrush roundels and came up with masking tape (which tends to rip off existing paint on EPO models) and plastic masks. I couldn't see how I could get a sharp line with plastic masks on the 3D curvy surface of the SE5A wing.
Then I thought of cling wrap. At first I applied water-based school glue to a test piece of EPS foam (the inner box of the SE5A itself!) and then stretched cling wrap over it and left it in the sun. This didn't work as the glue didn't dry at all.
Next I applied the same glue thinly over the EPS and left this in the sun. It took a surprisingly long time to become tacky - at least half an hour. I then applied the cling wrap to the tacky EPS, just floating it onto the centre and then smoothing out towards the outside with my fingers. It went on easily and without air bubbles. Then I set my compasses up with a craft knife blade instead of the pencil lead at about 45 degrees and marked a centre point. I put a small drop of CA + kicker on this point so the compasses wouldn't sink in too far and scribed a circle very gently. I lifted the round cut-out and airbrushed the hole, lifting the cling wrap immediately after painting. The result appears to be a perfect circle, with no paint bled under the cling wrap..
I then removed the existing decals from the upper wing of my SE5A by dipping them in water at 80 degrees C or a bit cooler, which I know doesn't cause alligator skin. I then smoothed any edges on the top of the wing - a small fillet of filler at the edges of the plastic plates for the interplane struts and inter aileron links.
You then make a good centre point using something like epoxy in a hole maybe 4mm diameter where the centre will be, and establish the exact centre. Mark the size of the roundel rings lightly with a pencil. Then apply the school glue and let it go tacky, note that it will go tacky very much faster if the surface is dark and it is in the sun. If it goes too dry just remoisten it with a damp cloth rather than applying more glue. Apply some glue under the wing so the cling wrap can be attached there.
Then put on the cling wrap and cut out the two outer circles. Remove the cut cling wrap ring by pulling mostly sideways rather than upwards (I cut the ring with scissors in order to do this). Once you have done this, remove the glue from the exposed foam circle by using a damp cloth and sponging always away from the cling wrap edges.
When airbrushing always spray away from the cling wrap edge rather than towards it, in order not to lift the cling wrap. You can also use a brush to apply the acrylic, in which case brush away from the cling wrap edges and don’t dilute the acrylic much.
Leave the cling wrap on while the acrylic is drying so the glue doesn’t become dry. Only once the acrylic is very well dry should you remove the cling wrap and then the school glue with a wet/damp cloth. Remove the glue particularly if you are going to spray another area.
Repeat for the other roundel rings and colours, working inward. When the whole thing is finished and dry, carefully remove all traces of the glue. You can then overcoat with WBPU if you want.
Although this method refers only to acrylic paint, there is no reason why you shouldn’t use it with other paint types, e.g spray cans, oil paints etc.
Good luck, Richard

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