|My watercolour lightfast tests on the outside |
of a north-facing glass window.
I returned them to their north facing window, which is a pretty harsh environment for watercolour, and have just scanned them. Note I am in Sydney, Australia, so that is the same as a south-facing window in the Northern Hemisphere, though Australian sun is very harsh. The biggest changes happened during the first seven months. Not much further change has occurred.
The first row is all fine except Aureolin, PY40, which should not be used as a watercolour. Notice the light wash is now creamy and not yellow at all. The mass-tone is dull and greyed.
In the top row, there is a possible slight yellowing of Manganese Blue PB33 Old Holland but it is very slight. Flesh Tint, Old Holland, with is a mix of a number of pigments, has really faded out.
It is a very valuable exercise to do a light-fast test of the colours you use as the manufacturer's labels may not always be accurate. Keep away from PY40, PR83 and, it seems, PB27.
September 2014 update: My other lightfast tests, using the colours I have chosen for my palette and other extras, were reported here. They have continued to hang inside my window and I see no changed in any of these colours. Whew!