With a little practice, you can use glazes to create special decorative techniques which will match those of a professional painter. A glaze is a thin, almost transparent film of oil based colour which is usually diluted with turps. The oil slows the glaze's drying time but you still have to work fast, especially when the weather is hot.

Glazes can be put over surfaces coated with an oil based paint, undercoat or eggshell using tech­niques called sponging, ragging, dragging and stippling. Sponging and ragging take less time to do than the others. Whichever decorative technique you are going to use, thoroughly prepare the surface first. Dragging, in particular, will otherwise highlight bumps in an uneven wall. Then put on the base coat and leave it to dry. Never use a gloss finish because glaze will not adhere to it.

You can buy transparent oil based glaze, called scumble glaze, which varies in shade from pale to mid brown, from specialist paint shops. As a rough guide, a 2 litre tin of glaze will be enough to cover all the walls in a room 3.7m x 3.7m x 3m.

Use artist's oil colours or universal stainers to tint the glaze to the colour you want. Mixing a glaze to achieve a particular colour is a matter of trial and error which becomes easier with practice. Always mix up more glaze than you think you need, it is impossible to match a colour if you run out halfway through the job.

Whether you need to buy special tools depends on which techniques you are using. The brushes traditionally used for stippling and dragging are very expensive, so it may be worth sharing the cost with a friend, you cannot hire them.

[edit] Tinting The Glaze

1. Blend a small blob of colour (a little amount goes a long way) with turps.

2. Add this to the rest of the glaze in the paint kettle, stirring all the time to mix them well.

3. Test the result on the surface to be painted and repeat the process, if necessary, adding more of the same or a different colour until you are satisfied.

Glaze is usually diluted with some turps before you apply it to a surface. The consistency should be easy to work with, about the same as single cream. If the glaze thickens as you work this is because the turps has evaporated. Stir in some more turps, but be careful with the amount you put in because too much will weaken the colour.

Alternatively, you can achieve similar painting effects with egg shell or any mid sheen oil based paint, although the mixture is hot strictly a glaze.

Mix one part paint to two parts turps. It is best to choose white paint and then to tint it to the required colour. As with an ordinary glaze, blend a blob of colour with turps, add it to the paint mixture and try out the result. Keep blending more colour with the diluted paint until you achieve the colour you want. This 'glaze' dries quickly so it is more suited to the techniques of sponging and ragging than to dragging or stippling.

You can produce decorative effects with emulsion paint as well, one part diluted with three or four parts water, but this dries even faster.

Always apply an emulsion 'glaze' over an emulsion base coat, not an oil based one. Similarly, tint it with water soluble paints, use gouache, acrylic or poster paints. Dilute the emulsion with water, not turps.

[edit] Protecting the surface

It is advisable (but not essential) to protect a decorative finish with varnish. Make sure that the glazed surface is completely dry (this may take 24 hours or longer) before you do so.

Choose gloss, semi gloss or matt varnish, depending on how shiny you want the result to be, and buy varnish with as little colour in it as possible.

Brush on a thin coat, working from the top of the wall down. If you use two coats of varnish, allow the first to dry before you apply the second. Matt varnish, which gives a good flat finish but not a tough one, will not take a second coat.