Decal over bare plastic?

Hi all
for my latest project, i decided to not paint the plastic license plate part and just stick the decal on there since the plastic wont even be very visible under the decal. about half an hour after i put the decal on, a corner of the decal had mysteriously lifted itself from the plastic. i got a q-tip, moistened it and proceeded to padding it back down flat. a while later, the same thing happened. are decals not meant to be put on bare plastic?

this isnt a big problem as i have another of the same decal. i just want to know if i should paint the part before i apply a new decal.

Decals need a smooth surface to adhere well - in most cases, this means glossy paint. But you can put them on clear parts without paint, so I'd imagine that goes for any plastic. I'd imagine you'd have to wash the parts thoroughly to remove any mold release first, though - any surface contaminant could lead to the decal peeling away like you describe. If you're unsure, I'd say paint it just to be safe - it would be bad news to have it peel up 6 months down the road . . . .

What ever you do, DON'T DO IT! I was experimenting with this last week, and the results were anything but good. Decals do not adhere properly, and will start cracking. What ever you do, don't do it!

If you coat the back of the decal with Future it will stick and stay nicely. Apply it with a Q-Tip. You also can use a wahite glue that dries clear. For a license plate you could leave the backing on and glue in place with white glue. I build allot of racecars and have to deal with decals on windows which cannot be painted that methods work fine. Also make sure the plastic is very clean.

IIRC, I'm pretty sure that I have at some point put a decal straight on to bare plastic.

I don't see any reason why it shouldn't work under the same principles as over paint i.e. smooth, clean and grease-free surface. Using MICRO-SET or hot towels or a hairdryer to get it to settle well down.

In your case it rather sounds to me as if either the plastic part was greasy or perhaps you over-soaked the decal and lost a lot of the adhesive on the decal.

As suggested above, thinned PVA or future-style floor polish should help you "save the day" :D

In essence a smooth paint job is a smooth plastic surface. If the decal is peeling from an unpainted license plate, it's because either the plate isn't clean or the decal doesn't have enough adhesive. Either way, you can use the techniques described by 935K3 to get it to stick down. Decals work just fine on plastic if the surface is clean.

If you coat the back of the decal with Future it will stick and stay nicely. Apply it with a Q-Tip. You also can use a wahite glue that dries clear. For a license plate you could leave the backing on and glue in place with white glue. I build allot of racecars and have to deal with decals on windows which cannot be painted that methods work fine. Also make sure the plastic is very clean.
im sure i did put a window decal on epson nsx racecar (in which the car itself now is a total WRECK) (but the windscreem decal is in fact probably one of the best decal work ive ever done is still perfectly intact and indeed no cracks) withuot any outside help but the decal itself, some mr.mark setter, warm water, and some plys of tissue paper.. all that makes the difference in my experiments is that it works best if you wash your bare plastic with soap, leave it for a few minutes, and dry it perfecty to release the molding release agent..(i heated an oven, then after it releases hot air that you can feel, i turn it off, and place the plastic near the hot air to evaporate the water perfectly):rofl: