thankyou The_Distiller! got it working thanks to your screenshot in a new level but in my working raytraced scene with post process volume no joy [well at least not visibly].
I show two shots one shows the PPV on the second I disabled the PPV and the thins translucency is visible.
This shows [i have really bad UVs on the headlamp cover;)] and that something in my ppv is messing with the result. I ticked through the ppv settings and other than turning it off completely no other parameter seemed to affect the scene in the viewport and allow the thin trans material applied geo to be visible…
will keep looking but would be grateful for any ideas.
I attach the PPV settings…sections are collapsed where there is nothing turned on within
cheers
Dan