Hi jsprogg, I'm pretty sure - although if it's not, it's slowing it enough to make it totally impractical (fairly simple scene, 1 light, and going from 20 secs to 2 minutes plus without updating), for only adding 1 attribute. The same connection method works for other materials, with only a slight increase in render time... making me think maybe the dielectric material works differently in this respect. cheers gubar