Sue Linton Artist

I'm painting an old Staffy cross blue cattle dog in pastel. It's the first Pastel I've done in months and at first I found it quite frustrating.
Pastel is an artist quality chalk - much richer colours and softer than school chalk and it lasts for 100's of years. He is a greying black dog.
If I'm creating a portrait of a black dog in Oil I can mix any colour I want. I can liven the painting up by using very dark purples , blues, greens etc for the darks .The overall effect will still be a black dog but much more interesting and alive than if I used black.
The problem with pastels is you have limited mixing - you pick the closest colour and put it on. You can layer a bit but for dark colours you are limited to the manufacturers offerings and they don't make many really gusty darks..
I finally worked out a way to get around this and I'm enjoying adding heaps of different colours.
When you layer thick layers of pastel it can come up like a painting , lighter sketchy application is more a drawing.I am using both techniques now.
You can only layer so much pastel onto the paper. The paper has a 'tooth' /surface that the pastel particles sit into so they stay on the paper. After a certain number of layers the tooth fills in and then you can't put any more on as the pastel skids over the surface.You have to plan the painting so you can get the effects you are after before the paper fills up so you can't finish it!
To show you the effects you can get here's an earlier Pastel I did of  Jack. He wasn't such a problem as he didn't have a lot of black on him.
 

Jack
20 x 30
framed pastel

Here's  a pastel of a black dog

And some Oils

I don't know that the photos really show the difference very well but Oils allow me to get 3D a bit better as I can mix subtle variations of colour that come forward or recede. You can see it in the actual portraits.