I have been doing some more casting.
The different shades are because the resin has just been poured and is curing. Later on, and for the first time so far, I had a batch not cure properly and have to be thrown away. I suspect that I wasn't concentrating and didn't mix it thoroughly enough. I shall therefore pause and reflect before doing any more.
"Always draw fresh breath after outbursts of vanity and complacency ." - Franz Kafka