Issues with material transparency

[Jack]

Hello,

I am having issues with the transparency of a lid that is placed face down on a wooden worktop. The material is Clear Shiny Plastic White. I have tried raising it above the surface and increasing the ray bounces with no luck. The lid shows up black as can be seen from the image. I need it to look naturally transparent with the worktop visible through the material.

[richardfunnell]

You will probably also have to enable "Ground Illumination" if your parts are sitting on the ground plane.

If that wooden part is a piece of geometry, move your model up a very small amount (.1mm is fine) to add an air gap between the parts.

[Speedster]

I've had issues with transparent plastics.  Try "Glass" and "Solid Glass".  Test between "2-sided" and not.  You can tweak the color and refraction to get to the white.  And yes, a very slight air gap between the cap and table is essential.
Bill G