What are the difficulties in separating cast shadow from reflected Light and shade?
The difficulty in separating cast shadow from reflected light and shade is that there is very little tone difference between them and makes it hard to determine which is which. However the fact that they fall in opposite directions does help to determine which is which.
The reflected shadow and light follows the contours of the objects how have you shown this in your drawing?
To show how how reflected light follows the contours of the objects I used fluid strokes and hatching techniques as well as following the contours with a putty rubber.
For this exercise I drew a thumbnail drawing of my favourite coffee cup roughly 10 cm square in my small A5 sketchbook, which I’ve barely put to use so was good to fill a page or 2. Once I had finished the thumbnail drawing I drew a grid of 2 cm squares with an HB pencil over my thumbnail sketch.
In my A4 sketchbook I drew 3 cm squares, deciding they were a perfect size for this object on this size paper, with a larger more detailed composition I would have probably needed smaller squares in both sketchbooks.
To make it easier for myself to identify which squares I would be drawing in I labelled the squares with letters down the left hand side and numbers across the top. However the drawing was quite low in my A5 sketchbook so in my A4 sketchbook I started at B instead of A lifting the drawing up 1 square.
I loved this ‘Enlarging an Existing Image’ exercise, it was like piecing together a jigsaw puzzle but a hell of a lot easier and as the squares weren’t that big quite easy to judge where a line curves or which point of the grid they would meet. Admittedly I did do a little bit of rubbing out with an eraser but not that much.