Gesso ground for panels
Glue size (1: 15 water*)
Prepare a small quantity of size by soaking the glue granules in water until swollen. Warm the glue in a double boiler or a Pyrex glass basin, until melted. Remove from the heat source. Add a small amount of whiting to the size and stir gently with a brush. Test the mixture by painting onto a piece of waste wood; it should coat it with a milky film. Allow to dry for 12 hours.
Prepare a fresh batch of size (but this time with larger quantities) and melt as before. Start to add the whiting by slowly slipping it into the warm size; the solution will take a surprising amount of whiting. When the level of whiting is just below the surface of the size, and no more can be added, the correct amount has been added. This is easier to gauge with a glass basin. Resist the urge to stir the mixture and allow it to stand for 5 minutes before straining through a sieve into a clean basin. Take a wet hog’s hair brush and gently stir without lifting it out until the mixture feels smooth. The gesso can now be used and should be applied fairly generously, ignore slight imperfections as returning to them can cause the coating to lift away from the panel. Apply 5 or more coats, each time waiting for the previous one to go dull before recoating. In cold weather the mixture may start to gel during application and will have to be stood over warm water to loosen it, if this is necessary add a drop or two of water to compensate for the small amount of evaporation that will occur. Failure to do this will make the upper coats have a stronger glue content and may result in them peeling away. All coats should be applied in one session otherwise the coats will not bond together, so it is just as convenient to make several panels at one sitting.
Allow the panel to dry before smoothing down.
If the resulting gesso is fairly level and free from ridges, it may be sufficient to polish it with a piece of damp cotton until a smooth porcelain finish is achieved. If the surface is ridged it will need to be levelled before smoothing either by sanding or using a scraper, the latter creates less dust. To use the scraper it should be held almost vertically and pulled towards you following a zigzag or lattice pattern.
To complete the process the surface should be made perfect by sanding lightly with fine wet and dry paper.
The surface of gesso is unlike any other and is the only one that will accept water gilding and true egg tempera.
*Based on Kremer pigment Rabbit skin glue (code 63020)