What is Bister…. How do I use it?

Instructions Powertex Bister/patina liquid (ready made).
The Bister in packages of 250ml and 500ml is ready for use. Imported from Powertex International, Belgium.

The easiest way to use Bister:
Pour some bister in a spray bottle. Pour a small amount of Powertex Ivory, Yellow Ochre or Terracotta in the middle of a stretched canvas. Spread the Powertex over the canvas with a spatula, make sure you have differences in thickness. Spray one or more colours of bister (see coloured bister) next to or on top of each other. Carefully dry the layers with a blow dryer; start on the thinnest layers, then slowly move to the thicker ones. You will see the cracks appear immediately. When everything is dry, it is possible to remove some of the bister with a damp sponge. Be careful not to wipe away too much bister from the cracked surfaces.

Important: bister is not water resistant and needs a protective layer of varnish before going outside. Paintings with bister need to be protected as well, preferably with a layer of varnish from a spray can.

Instructions Powertex Coloured Bister (powder 40ml). 
Take an empty (spray) bottle (app. 100ml) and fill it with water. Add a teaspoon of bister powder, put the lid on the bottle and shake well. Pour the mixture through a very fine sieve if there are some granules left. If you need to preserve the mixture for a while, it is best to use distilled water. Use the spray as described in the instructions for the ready made Bister. For a lighter result, add more water to the mixture or directly onto the piece. To intensify the colour, add a few granules of bister onto the piece and spread well with a brush.