INTERFACING A DRIED GESSO, ILLUMINATOR’S BOLE,
This process, called Interfacing comes from one of the chapters from The Technique of Raised Gilding. 1992, Michelle Jordan Publication. The author: Jerry Tresser
How to add wet gesso to dry gesso, or how to add a second layer of Illuminator’s Bole to a dried bole size. This would probably work well with any dried size that needs to be increased in size or remedied because of an unsightly drying process.
One of the problems when working with gesso that has been made as an illumination size which has slaked plaster is that for whatever reason (mostly related to humidity) the gesso often dries in different heights on the same item or its neighbor, being gessoed. This can be a problem if you are writing letters or creating different objects that contain the plaster-based gesso.
The question becomes: how we keep everything at the same height once dried. More importantly, if the gesso dries and the heights are uneven how do we add more gesso to make sure the objects are raised if necessary and uniform in height?
One thing you should not do is add water to soften the gesso, or just add more gesso. With a slaked plaster base, you CANNOT add something wet to something dry. So just adding some more gesso to increase its height is out! Nor should you add any water to soften the gesso. That would be disastrous as the water would seep down the gesso and destroy or weaken the foundation of the plaster.
The answer is rubbing alcohol. Commonly call Isopropyl Alcohol. The term is called Interfacing. You may need to sand the surface of what is being raised with very fine sandpaper. Basically to eliminate any facial imperfections before applying the alcohol. When ready, just take a brush dampen the gesso lightly with the alcohol and immediately add the fresh prepared gesso
. Alcohol dries almost immediately on contact with the air. But allows enough wetness to allow attachment with something dry to something wet. If additional layers are necessary, allow the gesso to dry completely and re apply the process again. This type of surgery is done in the application stage. Here is where we fix things. a WORD OF CAUTION
. Illumination gesso is like a turtle. A hard-outside shell but a soft inside body, so allow the gesso time to dry before adding any additional layers. Or you will kill it..
When using Illuminator’s Bole, the process is the same with one exception. Heat up the bole on hot plate to get it warm (not hot) and then apply it with a brush to the dry bole after swabbing it with alcohol. This is the proper way to use a raising preparation for all sizes…