The old colour scheme wasn't very good at showing ice either.......
In the early '80s we were on a trip from Singapore to Brunei (to visit the same ex-ascoteer) when, climbing through FL170, the rate of climb dropped drastically. By the time we reached FL180 the ROC had dropped to zero and the speed started to decay.
We were flying in daylight and, although there were cb's nearby, we were clear of them. Being the Tropics there was a lot of moisture in the air.
An 'animated' discussion followed, including the possibility of ice accretion. Looking along the wings, they looked normal but, on closer inspection, the sun's reflection looked a bit strange. We selected the Wing Anti-Ice 'ON' and were amazed to see huge sheets of clear ice peel off the upper surfaces of the wings. The a/c started to climb again and we went on our way, having learned a salutary lesson. Incidentally, we had no ENG ICE warning.
A few years later I was on HTS, route checking a crew member between Dulles and Belize. It was summer and there was a lot of cb activity around Dulles. During the climb the same thing happened. I suggested to the crew that they might like to operate the anti-ice and watch the wings. They were amazed as the sheets of ice flew off the wings and, afterwards, looked at me as if I was some sort of guru.
I came clean and told them about the SIN incident........after they'd bought me a few beers in Belize
I remember, after the first incident, I calculated an approximate weight of the ice on the wings. I worked out the area of the wings then using an average ice thickness of 1" came to a weight of ice.
Unfortunately, that was a long time ago and I can't remember the figure - but it was significant.
I'm sure there is an ex G/E on here who could help us out...........