I had a couple of brief moments of waiting for my companions on a local hike recently and I sketched. But with some unexpected frustration: both reds in my pocket palette lost the pigment completely. Both my Cadmium Red and Alizarin Crimson just fossilized.
This is a hike that in winter is very blue and green. At least that is how I think about it, so I did not need reds too much - but I missed mixing grays for the shadows and tree trunks and roads and trails!
There was no return of pigment no matter what I tried at home - including soaking for multiple days and grinding and then soaking, grinding, and adding binding agents - nothing worked - the best I got back after a lot of work was very weak gray.
But now I refilled the palette and hopefully am ready for the next hike!