Leaving the paper exposed around the image will also give quite different effects. Low key colours on pale backgrounds will make comfortable pictures, relaxing to look at.
Using high key colours on strongly coloured backgrounds will make striking pictures which will dominate the room they hang in.
Textured acrylic mediums, modelling paste and acrylic colours can be used as underpaintings for pastel. The added texture breaks up the colour surface visually and gives the pastel something to stick to.
For experimental techniques pastel can be crumbled into wet mediums which will act like a glue. Remember, the medium on its own will dry clear, leaving only the additive texture showing. Mix acrylic colours into the mediums first if you want texture and colour.
Pastel can be moved around on the paper by using water. The wet brush will drive the pastel particles into the paper and a blending effect will be left on the paper when the water has dried.
If you want to work with heavier layers of pastel, try a drop of Gum Arabic in the water. This will help the pastel to stick to the paper once the water is dry. Don't use too much or the pastel will dry glossy.
Pastel can be successfully combined with any water based mediums or colours. Colourful effects are achieved by using the paints on heavy water colour paper with the pastels on top.
Avoid the use of thick layers of acrylic as you will find the pastel won't stick very well. This can be resolved by mixing the acrylic with a little Clear Gesso Base first, this will give it some tooth and then the pastel will adhere better.
A soft hair brush is useful for brushing away excess dust whilst you're working or for soft blending. Hog brushes are stiffer and will blend the colours well into the paper for initial backgrounds.
Paper torchons are sold for use with pastels and these both lift and blend colours. A putty rubber is the traditional blending and lifting tool for pastel artists, usually moulded into a working point or edge between your fingers.
With continual work, even textured surfaces will become clogged and it will be difficult to apply anymore pastel. At this stage the surface will probably look overworked. Soak a new piece of water colour paper in water for five minutes, leave to drain and sponge it damp dry. Place this over the picture, making sure you do not move it by mistake. Carefully press over the surface and then lift. A significant amount of pastel will have transferred to the damp sheet. Leave the original to dry, it will then accept more pastel. You might even like the transfer image better and be able to use that too!
A short flat hog brush can also be used for rescues, it will remove pastel dust from the surface, leaving just a background colour. For areas where you want to remove as much colour as possible, a white vinyl rubber is indispensable.
Pastel pictures are fragile as the particles on the paper are not surrounded by binder. A coat or two of fixative will give that little bit of protection, saving the picture from smudging in a portfolio or if brushed against by mistake.
A light coat of fixative will also help to stop pastel dust sticking onto the glass once the picture is framed. A coating of fixative improves the lightfastness of pastels, this is particularly recommended for any colours which are 'B' rated. Too much fixative however will cause considerable colour change to a pastel picture as the fixative wets out the pigment.
Some styles of pastel work look best without fixative and some artists just don't like working with it. Here are some methods which will reduce the fragility of unfixed pictures;
Experimental work can be fixed by using Acrylic Fluid Matt Medium to hold down heavy layers or large particles of charcoal or pastel. Up to 10% water can be used to dilute the medium and reduce the thickness of the film applied but the more water you add the more the paper can cockle. Use a garden spray and keep the work horizontal whilst the acrylic dries.
The fragile dusty surface of a finished pastel is best protected behind glass. Glazed frames should use a mount (mat) or spacer to ensure the glass is not against the picture. This will allow air to circulate and help to prevent condensation. Remember to fix the picture lightly before it goes into the frame; without fixing, pastel dust can build up on the inside of the glass as a result of static.
With a little care, pictures can be safely stored in portfolios if they are not yet to be framed. Firstly, apply a light coat of fixative for some initial protection. The main thing is to prevent the pictures from slipping against each other.
Place each picture between a mountboard and a sheet of tissue paper and place in a loose portfolio or a folio sleeve. Continue stacking your work in this manner and if you don't fill the portfolio by the end, do so with spare cardboard which will stop anything moving about inside.