Shrinky Don’ts

As I’ve mentioned in other posts, I love to try different media and one of the more quirky ones I’ve tried and enjoyed is shrink plastic, most famously known by the brand name Shrinky Dinks.  This plastic is meant to be drawn on, trimmed with scissors into some sort of shape, then heated to make the plastic shrink in size, usually to about 1/5 the size of the original drawing.  Shrink plastic comes in sheets about the same size as normal paper, and it is either translucent or opaque with one side that’s been roughed up by sandpaper or the like. This roughed surface allows various art media to be drawn on without worrying about wiping it off by accident; it gives the pigments something to stick to. The most common way to colour on shrink plastic is probably markers, chalk pastel or pencil crayons, though they do also sell a special inkjet-printable version of the sheets where your inkjet printer works in basically the same way as using a marker.

But if you look at the instructions that come with a pack of Shrinky Dink sheets, they also mention acrylic paint. And I am here to tell you all, from the depths of my struggles with acrylic paint and shrink plastic – DO NOT USE ACRYLIC ON SHRINK PLASTIC.

At least, don’t use it without getting a heavily-watered down version of acrylic paint, which is what they probably meant because they do also mention specifically acrylic markers.  But they should have just stuck with the markers and not mentioned the word “paint” at all, because then you get artsy yahoos like yours-truly going “Acrylic paint? I have acrylic paint and brushes! I’m going to paint me some shrink plastic pendants whee!”

So why not use acrylic paint? Because acrylic is a form of plastic and as it dries, it turns into a very thin plastic film sitting on top of the shrink plastic sheet.  This is different from markers or pencil crayons and chalk pastel, because with those pigments, their binding agent does not remain on the sheet after you’ve drawn (marker liquid evapourates and chalk/pencils use friction to remove pigment from the bound core) so each pigment is not directly connected to the one beside it. As you go to shrink your shrink plastic, by using heat either from a small convection oven or heatgun (I use the oven myself), the shrink plastic surface painted with acrylic becomes suddenly much smaller while the amount of acrylic paint stays the same with nowhere to go, and you get two bad things happening:

  1. little bunches of acrylic that end up becoming lumps
  2. the acrylic can’t handle the flexing and just flakes right off, leaving an unpainted spot

Both results do not look very nice on your now-shrunken pendant or charm or what-have-you.  At this point, you can grab your acrylic and try to touch up the flaked off spots (hoping that you don’t accidentally trigger more flaking) but there’s not much you can do about the lumps.

And I would like to mention, even though the instructions don’t mention them, that I have also done experiments with gouache paint, which is more like watercolour paint than acrylic, but I experienced the same bunching and flaking with gouache.  I suspect it’s not just the plastic film of acrylic that’s the problem, it seems that any media where pigment bits are deposited very close together could pose a problem when the shrink plastic starts to shrink.  Personally, I find I’ve gotten the best results with pencil crayons for the translucent sheets and markers work just fine for the opaque white stuff.

~Sunhawk

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