I had only acrylics to hand for this study. I would have preferred oils but I was away from the studio -in South Kerry, if you must know! I found that the problem was to keep the paint wet and workable while moving from background to subject -not a problem with oils of course. I added an acrylic medium, which helped a bit. The light was changing all the time, too, which made the reflections on the glass fleeting. 10" x 12" canvas.