"Five cats" painting process

Once upon a time I thought cutting my own mats would be beneficial. I no longer remember what made me think that, other than that they would be immediately available instead of going through the somewhat irritating process of ordering them from my art supplier, at the same cost no less. Worse, I found cutting them nearly impossible with clean cuts, and being impatient, I returned to ordering my mats like a sane person. Leaving the mat boards, 60×80cm black boards with white core, unemployed. I had read about people using them to draw and paint on but the foamy core made me sceptical. Still - nothing ventured, nothing gained, and I used a mat board for this painting, to be entered into an international art magazine's competition (sadly I was not chosen as a finalist). While the format seemed nice at first, for easier storage and handling, I cut it to 50×70cm. Some time ago I went into the habit of collecting my leftover paints into a jar for further use, and use the greenis...