I usually paint using watercolour pencils but sometimes use chalk pastels for landscapes, as the skies come up beautifully. Pastels have a quality of their own and the colours are always vibrant. However, as soon as I apply fixative the colours become dull and skies that were once bright and sunny look dull and lifeless. Can you advise me?

Margaret Evans replies: I am always being asked about this problem with fixative. If it dulls the colours on a pastel, you are either spraying on too much and applying it too closely to the painting, or perhaps you are using an inferior quality paper and the pastel is being saturated by the fixative. When using a fixative, always spray a minimum of 28 cm (12 in) away from the painting and keep the can moving across as you spray to prevent the fixative soaking into the paper. If you are using cartridge paper, sugar paper or something similar, the paper will tend to stain as it is very absorbent.