What is a crackle glaze or crackle varnish? Well, it’s a finish that is applied to various surfaces which imitates the fine cracks that appear in varnishes, painted surfaces and china, over long periods of time.
Many people who come to the crackle glaze for the first time end up confused because there are so many types of glaze. There are glazes which are intended solely for use with painted surfaces. With this type of glaze, you apply a coat of emulsion paint and allow to dry. Then apply the crackle glaze and allow to become tacky, then another coat of emulsion is applied and cracks form as the paint dries.
This is a 1 part crackle varnish and only for use with emulsion based painted surfaces.
Another type of crackle glaze comes in two parts and can be applied to many different surfaces. In the past this type of crackle varnish had an oil based base coat, and a water based top coat. The base coat was applied and allowed to become tacky, after about 30 minutes the water based top coat was applied, as the top coat dried so the cracks appeared, with this type of crackle varnish, the thicker the top coat the wider the cracks would appear.
The problem with this type of crackle glaze was that you had to do a good deal of trial and error to get the effect you wanted, the effect achieved depends on the local climate, the temperature, humidity etc.
Now there is a modern, reliable two part acrylic based crackle varnish which has taken a lot of the guesswork out of the process. Like the 2 part oil and water glaze this acrylic type of glaze can be applied to many different surfaces including china and glass.
With the acryliccrackle varnish application is simple, you apply the base coat, making sure to apply a thin even coat, wait for 30 minutes till the base coat is dry. When first applied it will appear milky, as it dries it becomes transparent. Then apply the top coat, once again ensuring you apply a thin even coat. As the top coat dries so the cracks will form, though they may be difficult to see at first.
When using a two part crackle glaze it is often difficult to see the cracks which have formed. It is usual after the glaze is dry, to apply what is called an antique glaze, this highlights any cracks.
This rather grand sounding name actually masks a very simple process.
All you need is a tube of student grade oil paint; burnt umber is the colour you want.
Apply a little to a soft cloth and rub all over the piece of work, a little goes a long way.
As you do this you will see the cracks appear in the work. Using a clean cloth, rub over the piece to remove the surplus of oil paint.
Depending on what surface you apply the glaze to; you may opt for sealing the piece of work with a lacquer or varnish.
By Richard Norman