How to Make a Clear Part with Opaque Back?

Hi,

I am designing a product that is transparent/translucent but needs the back layer to be white opaque.

From a manufacturing standpoint, what is the best / cost effective way to do it?

  1. Painting? Mask off the front and spray paint the back side?
    or
  2. 2-Shot injection molding? A layer is transparent/translucent and back is thin layer of solid opaque plastic. How thin can 2-Shot injection layers be? My total product is only 2MM thick.
    or
  3. In Mold Decoration / In Mold Label No masking but using IMD or IML to make the back side opaque with a then opaque label. Is this pricey? I though tit would save on the masking one would have to do in th epainting option.

Depend on the shape. Difficult shape can use centrifugal casting transparent plastic first and then the opaque.

2 shot injection is good if its allot of loose flat parts. And need 2 mold for this.

Cheap is fill it with paint and pour out the excess paint. This just for shape not use for final product unless its a vase or made from glass.

Thanks for the reply.

what do you mean losose parts?

So it will cost double the normal tooling?

We need a bit more explanation of the part before we can give you a “best” solution.

Is it a lens? Is it an organic part with bosses on the back?

If possible, posting a jpg of the actual part would be best, but I understand that might not be possible due to NDAs, etc.

PM/email me and I would be happy to give you my $0.02 outside this public forum.