Decal throught transparent material Q

I have been trying to simulate a silkscreen graphic on one side of a
transparent Plexi part. The decal would be printed with white, then the
graphics on top, so the effect would be on the front side to see the
graphic, but on the back side to only see white.

I have been doing these very simply using PW system options to use SW
materials, not physical materials. I have simply selected white
material, and changes the transparency to 60%. Great thing about this
is it renders really fast, even with a lot of graphic applied.

I have tried without success to:
1.
select the face and make it non-transparent. This looks correct on
screen and rendered, but as soon as there is a decal, regardless of the
decal setting, it shows through from the back.
2.
apply a white decal under the image decal. I would think this should
work since the stacking order of decals does work, but it may not like
or recognise white? Looks the same with the other image coming through.

I actually have 2 decals already stacked - a logo, and an image under
it. That looks correct from both sides, i.e. the logo as the top decal
shows only from the first side, but is blocked by the image below it
when viewed from the other side.

3. I also tried making a surface offset to apply to graphics onto, but
that does not work either.

Anyone with a trick up their sleeve?

Daniel

 

Small correction to the info below – in fact, the layered decals only
look correct from the first side. All decals show through the backside.

I am assuming this has something to do with surface normals. When you
make a rectangular block transparent, the inside faces are pointing
inward, and cause the decals to all be visible.

 

I would suggest making the decal a part that is very thin, then applying it
to your clear part.

 

Yes, that will work, but it is "dirty" )

I have not tested it, but I think this is a problem for most programs
relative to surface normals.