Varnish an icon with a brush 

Choose the right varnish. There are many different types of varnish, it is important to choose a varnish that is compatible with the type of paint on your icon.
Prepare the varnish. If the varnish is too thick, you can dilute it with its thinner, here white spirit.
Apply polish to the icon. Use a soft, flat brush to apply the polish in thin, even coats.
Let the varnish dry for 24 hours between each coat.
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