RAISED GILDING USING TITANIUM DIOXIDE
One of several formulas that I developed in the late 70s and was published as part of a workshop review in an SOS newsletter dealt with using Titanium dioxide as a substitute for Lead carbonate commonly called White Lead. This workshop occurred during the early 80s. The formula is copywrited . The author has no problem in anyone using it or publishing it providing that credit is given to JERRY TRESSER
The Cennini formula that was developed in the early 14th century used Lead carbonate as a filler in the preparation of the gesso. Lead carbonate is poisonous(accumulative). This chemical had a 1000 year history as being an indispensible white, in pigment production . It was the leading coloring agent prior to Zinc White (Chinese white) entering the market. Lead carbonate was used exclusively for murals, frescos, panels, etc. And has remained the filler for manuscript gessos as a necessary ingredient in combination with slaked plaster for Gold works on vellum. There is no substitute for white lead. It has remained that way as of this writing. Using TD provides an alternative which will change the formula, as a more modern approach with greater limitations. It is not a real substitute with the same properties as Lead carbonate. It is a different gesso, harmless in its use, but provides some difficulties that are listed below.
Here is the formula for Titanium Dioxide Gilding and some of my early
notes and observations on this method which seems to have a resurgance recently within the calligraphic market as a raising preparation that is non poisonous.
PART I
8 parts of Slaked plaster of Paris (Calcium sulphate di hydrate)
3 parts of Titanium dioxide
a pinch of Armenian bole (for color)
the above dry ingredients are mixed together and placed in a blender
PART II
2 parts Hide glue (bovine)
*1 1/2 parts sugar water solution (see below)
2 parts water (tap or distilled)
*take 4 teaspoons of sugar and dissolve it into 1 oz. of warm water. Then take the measured amount needed as your sugar water solution.
Add all the wet materials in the blender with the dry mix . Once blended well, the mix will be creamy thick and pinkish in color. Using a spatula gather the gesso up an put the mix in air tight containers for later use.
When ready for use, you may notice a separation of the liquid from the solid mix. Just rester , and the mix is ready for use. This formula has certain drawbacks which should be noted.
NOTES & OBSERVATIONS ON THE TD GESSO
First of all, It should not be diluted with water from an outside source. If you feel its necessary to dilute the gesso so that it can flow thru your nib or ruling pen, here is how it should be done. When the mix is idle, the liquid will begin to separate. Using a medicine dropper , draw up some of this liquid and put it aside. Stir the gesso and take some out, and dilute it with the liquid from the medicine dropper. Basically you are diluting the gesso from its own internal materials. When the mix is not in use, it is normal for the gesso to separate. It just needs to be restirred. It remains in a semi-liquid state for immediate use. If you have to dilute it with water try to use a set amount of gesso and a set amount of water drops so that the process can be repeated if you are satisfied with the results.
Once dry, the TD gesso becomes very hard. It has a leathery appearance, and becomes difficult if not impossible to correct any blemishes or imperfections on the face of the gesso. The gesso is very unforgiving. The gesso hardens and becomes difficult to address after the first 24 hours. Make your corrections as soon as possible.
Their are 2 options that I have used successfully. The first method is to use fine sandpaper and carefully scrape the surface where the problem area resides. Use an Agate burnisher and polish the sanded area until it gets smooth. Hopefully this will eliminate the problem, but if not, then use
the 2nd method. Using a fine brush, dab the problem area with alcohol. Rubbing is fine. This should soften up the surface and clear the blemish. You also have at this point the opportunity of using a very diluted amount of TD gesso (see notes above for diluting) and after you have added the alcohol, add some fresh gesso on top of it while it is still damp. In order for gesso to receive gesso, it must be interfaced . The above method with alcohol will achieve that process. Its called INTERFACING the gesso.
Once you are satisfied with the appearance of the gesso, it is now ready to take the Gold. Breathe on the face of the gesso. A few short breaths thru a breathing tube then apply the patent Gold without delay. The gesso remains hygroscopic for only several seconds The gesso will take the Gold beautifully. Make sure the entire gesso is covered. From that point on, LEAVE IT ALONE. The gilded object is like a turtle. A hard outside shell, but a soft inside body. Many quality gessos have been destroyed because of impatience in attempting to burnish before the gesso was really hard. It may take several hours.
The TD gesso works well. It produces a very good shine. It was developed as a secondary means for me to make a quick batch when needed. My own personal thoughts and methods continuously move back to the original formula derived by Cennini in the 14th century. Aside from using white lead, I find Cennini's recipe far more flexible in fixing problems on the surface of the gesso as well as thinning it with water or glair. The use of white lead if handled properly, is a negligible factor and the amount is very small. The exposure is also very limited. But I can understand peoples concerns, so here is an alternative which I hope will be enjoyed by everyone
A note about burnishing marks. Sometimes when polishing or burnishing the gesso
or Gold, you may overstep the boundries of the gesso and accidentally leave a shadow mark on your paper or vellum. To revitalize the paper or vellum, use a
small amount of rubbing alcohol and brush it on lightly to that area. Alcohol dries
quickly and will eliminate the mark which can be unsightly.
