Each of these graphic media, he likes to say, sets its own technical tests for the artist. The Rapidograph required extreme concentration, because there was no possibility of erasure and correction. With charcoal, changes are much easier, but, he points out, you can’t put your hand on the drawing because it will smudge. Watercolour is equally unforgiving in another way: put too many layers on top of each other and it will go muddy. Conversely, each of these methods presents unique possibilities. The almost miraculous evocation of light, shadow, and reflection in those charcoal views of puddles and burgeoning vegetation along the East Yorkshire road called Woldgate could not have been achieved with a Rapidograph; nor could the Grecian elegance of his Rapidograph works have been accomplished with charcoal or crayon. He is a connoisseur of effects that can be obtained with various kinds of line, sometimes in unexpected places.

Martin Gayford

Add this to the what I wish I knew when I was younger list. Each type of graphic media has it’s strengths, and coupled with that, it’s drawbacks.

The key is knowing when which method is best to use.

Gayford, Martin, and Hockney, David. Spring Cannot Be Cancelled: David Hockney in Normandy. United Kingdom, Thames & Hudson, 2021. pp84