A MODERN SPIN ON
TRADITIONAL GESSO
(Thanks to Reggie Ezell,
a well known mundane calligraphy instructor from Chicago)
"Gesso" is a generic term traditionally used to describe any plaster based ground used for priming or preparing surfaces to be painted, "Gilding Base" is also another descriptive term.  Varieties of gesso recipes evolved for specific purposes, one of which was a base to which gold leaf would adhere and burnish up.  Modern acrylic gesso is made for priming canvases and other surfaces, but should NOT be confused as a substitute for the type of traditional gilding base we are preparing here.

 The recipe given here is quite traditional, with only apparent changes.  Purer chemical equivalents have been substituted for traditional ingredients when they improved either the dependability or burnish of the gesso.  The names only seem different, but they are truly, in essence, the same.
 

THE INGREDIENTS
  • CALCIUM SULFATE DIHYDRATE:     The commercially prepared chemical equivalent of slaked plaster.  CaSO4.2H20 is superior in purity and consistency to the home-made galvanized bucket/wooden spoon method or product.  Those who would like to pursue this 6-week long process can find it in Graily Hewitt's "Lettering."  This ingredient gives bulk and body to the gesso.
  • WHITE LEAD:       Poisonous if inhaled or ingested over prolonged, repeated periods.  With reasonable care, it is safe, however.  It gives malleability, bulk, and body to the gesso.  Substitutes will be discussed later.
  • FISH GLUE:      Seccotine glue binds the ingredients together and onto the paper (or vellum).  It has the quality of remaining flexible after it has dried.  This is especially important in a book where the page is turned.  Fish glue from a jar rather than a tube is preferable, as it will not have glycerin in it.  The glue is hygroscopic — which means it draws moisture from out of the air.
  • PURE CANE SUGAR:      Not beet sugar.  Easy to obtain in the US, but more difficult in Europe, where rock candy (made from cane sugar) is used.  It is also hygroscopic.  Do not use powdered sugar, as it contains corn starch.
  • RED DRY PIGMENT:      Both Windsor Newton Indian Red and Venetian Red dry pigments are chemical equivalents of Armenian Bole (a finer form of jeweler's rouge), and are consistently more finely ground.  This gives the gesso a pinkish color.  This color base gives the extremely thin gold leaf a warmer, richer cast or appearance.  Cadmium Red can even be used!  (NOTE:  use Ultramarine Blue for silver or aluminum leaf.)
  • DISTILLED WATER:     Pure, not mineral water.
  • A  1/8 TSP MEASURE:     Most dependable size of measure for the grinding time shown.  Increase the unit of measure to ¼ tsp and you double the grinding time.  (Since this measuring spoon is also used for the lead, be sure it never gets mixed up with your cooking ones!!)
  • METHOD of GRINDING:     An unglazed ceramic mortar, about 3" to 4" wide, and a pestle will grind the gesso most completely and homogeneously.  Other methods (ground glass and a flat muller) are not as thorough (according to Reggie) and are more costly.  The 4" mortar comes with a pestle whose handle is long enough to generate greater leverage, grinding more efficiently and wearying the hand less.  When you begin grinding the gesso, it should be the consistency of thin cream (like half & half).  That consistency should be maintained by adding a little distilled water every 5 to 10 minutes.  It starts off a bit lumpy and granular, but smooths out nicely while grinding.
  • PREPARATION OF TRADITIONAL GESSO

    MATERIALS:
    "WET" INGREDIENTS:
    "DRY" INGREDIENTS:
    • 3" -  4" mortar & pestle
    • 6 craft sticks
    • paper towels
    • 1/8  tsp measuring spoon
    • shot class with rounded inner bottom
    • 8½" X 11" sheet of bond paper
    • gesso ingredients (note the "wet" and "dry" separations below)
    • 2 each 9" x 11" pieces of rigid cardboard covered with plastic wrap
    • 1 unit pure cane sugar (same as rock candy)
    • 1 pinch red (or blue) dry pigment (Armenian bole in old recipes)
    • 1+ unit of fish glue (seccotine)
    • 10 units distilled water

     
     
     
     

     

    • 8 units Calcium Sulfate DiHydrate (slaked plaster) CaSO4.2H20
    • 3 units white lead (2½ units of Titanium White dry pigment can be substituted)

     
     
     
     
     

     

    You start by mixing separate batches of the "wet" and "dry" ingredients for the gesso, for the same reason it is done with cake batter — to make a complete and thorough mixing of the ingredients from the outset.
    TWO  OF  THE  MOST   IMPORTANT  FACTORS IN  SUCCESS WITH GESSO IS  THE  COMPLETE MIXING  AND  THE  COMPLETE  GRINDING  OF THE   INGREDIENTS.   THIS  SEEMS  A  SIMPLE CONCEPT,  BUT IT  TAKES  ATTENDING TO AT SEVERAL  UNEXPECTED  STAGES.
    Grind up an excessive amount of sugar in the mortar to a powdered state.  Overfill the measuring spoon, compact it down, and level it off again.  Put it into the shot glass.  Discard the excess sugar and clean out the mortar.  Make sure it is dry before starting the next part.
    With a craft stick, put the merest bit of red pigment into the shot glass.
    Put a little more than a level spoon of the fish glue into the shot glass. Use the craft stick to coax out all the glue you can from the spoon.  Some will remain in the spoon, but the next part will take care of that.
    Put the first unit of distilled water into the spoon and stir it with the craft stick to dissolve any left and put it into the shot glass.  Use about 7 units of the water at this time, saving the remaining 3 units to be used very soon.  Dry off the measuring spoon.
    NOTE:        A word about the amount of glue in your recipe — it can vary.  Generally, for any gilding base (not just gesso) the stickier it is, the less brilliant the gold will burnish up.  However, the gold will stick — a mighty encouraging virtue to beginners or for someone working under a deadline.  Learn to experiment — use more glue in your first few tries at the recipe, and a bit less as you get more experienced.
    Stir all your "wet" ingredients with a craft stick for a few seconds (still in the shot glass).  That is all it will take for them to dissolve thoroughly.  Set the shot glass to one side.
    Put an 8½" x 11" sheet of bond paper in front of you on the table (a colored sheet might help you a bit).  Dip the measuring spoon into the Calcium Sulfate DiHydrate.  Compact it down with a craft stick and level it off.  Bring over to the bond paper and turn it upside down.  Tap out the contents to form a little mound.  Make 8 of these little mounds.  Carefully crease the paper and let all 8 mounds slide into the mortar.  You won't lose count with this method.
    Put the bond paper in front of you again and place the mortar in the center atop it.  Put the container with the white lead next to the mortar.  Very carefully and slowly, open the cap on the container to minimize the amount of white lead that might fly into the air.  Dip the measuring spoon into the container and use a craft stick to compact it down and level it off.  Do this over the original white lead container.  Place the 3 little mounds of white lead directly into the mortar.  Cap the container immediately and wrap up the stick and measuring spoon immediately in wet paper towels.  You can discard the craft stick and bond paper as soon as possible, and wash the measuring spoon VERY carefully as soon as possible.  Use another craft stick to slowly break apart and stir together the "dry" ingredients, but not vigorously.  You want to keep the amount of dust to a bare minimum.  Form a little mountain in the center of the mortar and then put a "crater" in the middle to hold the "wet" ingredients.
    Stir the "wet" ingredients thoroughly and pour about half into the "crater" of your mountain of "dry" ingredients.  A valuable tip on not wasting any of the "wet" ingredients while pouring from the ungainly shot glass: touch the craft stick to the lip of the shot glass and pour the liquid down the stick.  Now, with another craft stick, slowly stir the contents in the mortar.  Keep it from riding up the sides of the mortar.  It will not yet be a creamy consistency — far from it.  It will be more like bread dough with too much flour.  Stir the "wet" ingredients again and pour the remainder into the mortar.  You will be surprised to note that despite all your attention to detail, there is still probably a sizable amount of residue at the bottom of the shot glass.  Now, take the last 3 measures of distilled water and put them into the shot glass.  Stir and pour them into the mortar.  Stir the contents of the mortar slowly.  As lumpy and granular and bubbly as it may be, it should approximate the liquid consistency of thin cream.
    Put a few drops of distilled water on the head of the pestle and place it into the mortar.  Slowly, and with some force, begin grinding.  Grind for about 45 minutes.  Stop every 5 minutes or so and dribble a little distilled water down the pestle to keep the consistency of thin cream.  Some gesso will want to build up on the inner sides of the mortar.  Use your pestle to "wind" up the sides of the mortar as if you were unthreading the lid of a jar, then "wind" back down into the bottom of the mortar.  Don't do this too many times, just try to keep the pestle in the mass of the gesso.  Don't take it out to peer into the mortar to see what is going on, this will make air bubbles when you put it back in (not a good thing).  The grinding is tedious, so have a friend over to help or watch a mindless TV program (or maybe you need a mindless friend...<giggle>).
    Place the two plastic wrap covered boards in front of you.  Take the pestle out of the mixture.  Using another craft stick, wipe all the gesso off the pestle you can back into the mortar and set the pestle aside.  Gently stir the gesso with the craft stick.  It should be smooth now and the proper consistency (yes, thin cream).  Now, begin pouring out "buttons" of gesso about the size of nickels onto the boards.  When pouring the gesso out of the mortar, use the same trick with the craft stick against the lip as you did with the shot glass. ** It is important that you stir thoroughly before pouring out each and every button.**   When you can pour out no more gesso, add about 4 more units of distilled water to the mortar.  Slosh it around with the pestle, thus dissolving all the remaining gesso on each implement.  Pour this off into buttons (but just a little bigger as they are also a bit thinner).
    You may, if you wish, use the freshly prepared gesso directly on a work from out of the mortar (if you need to).  Usually, however, you will be storing the gesso as the dry buttons.  Let the buttons dry overnight.  Slit the plastic wrap and "pop" off the buttons.  They can be stored in an empty film canister, jar, or anything that will keep them dust and moisture free.  They will last indefinitely.


    RECONSTITUTING THE GESSO

    Crumple a gesso button into very small bits into the bottom of a shot class that has a rounded bottom inside.  Add a drop (or two at the most) of distilled water for each gesso button that has been crumpled...and wait at least 5 minutes.  During this time, the bits of gesso will absorb the water and soften just enough so you can put a finger cot on your finger and mass the bits into a mass at the bottom of the glass.  Cover the mass with a couple drops or so of distilled water and wait about 10 more minutes.  If any gesso is stuck to the finger cot, let it remain, because you will use it for more working of the gesso.  Bring the finger cot to the top inside of the glass and slowly "wind" it down along the inside for the slow stirring all the way down to the bottom of the mass of gesso.  Keep going until you feel everything is dissolved and smooth.  This should not take too long.
    Now, tilt the glass toward you and bring the finger cot up the side of the glass and over its lip.  Any bubbles that had been in the gesso should be congealed about the finger cot.  When it is wiped over the lip, the bubbles will immediately begin to slide back into the gesso.  You need to have a very vigilant pinky finger to make a hawk-like swoop down and whisk them away before they get all the way back to the rest of the gesso.  Immediately wipe your pinky on a damp paper towel.  The finger cot allows you to mix the gesso thoroughly, as you can feel when there are no more lumps or bits remaining while also protecting you from absorbing white lead (now in a liquid state) in through your skin.


    LAYING THE GESSO

    The gesso is now ready to lay.  Once again, check its fluidity so that it flows comfortably, with control, from our of whatever implement you are using — pen, brush, or quill.  Make sure whatever pen you are using is flexible enough to release the relatively thick fluid (like a distempered Mitchell nib without the reservoir).  If you are using a brush, dip it into some distilled water first and squeeze the water and air out of the hairs before dipping into the gesso.

    ** YOU DO NOT WANT TO LAY BUBBLES INTO YOUR GESSO!!  IF YOU DO, ATTEND TO THEM IMMEDIATELY OR YOUR GESSO WILL DRY WITH CRATERS IN THE SURFACE. **

    If you do get a bubble, stop immediately and pick up a straight pin or even an eyelash (one with no mascara on it, ladies) and wipe a little skin oil on it (you can use the side of the nose or from behind your ear).  It is the oil that breaks the surface tension of the bubble more than the sharpness of the implement you chose to "pop" it.  Continue laying the rest of the gesso.  Every time you dip into the gesso with a pen or brush, be sure to stir the gesso thoroughly.  This ensures there is no settling  in the shot glass and will make for the most dependable gilding results.  When using a pen, you really need to stir it well and then turn the nib over so that you use the cupped underside of the nib as a spoon to load.  You will want to lay down at least two or more "coats" of the gesso, being sure it is totally dry between.  The number of layers will depend on how raised you desire the base to be.

    If there is any gesso remaining in the shot glass when you have completed your gilding base, you can simply add just a little distilled water to it and then pour it back out into a button.  Let it dry and store as before.

    For the best results, your gesso should dry for no less than 6 hours — but overnight is probably better.  The time range depends on the temperature and humidity in the room and on your technical skill, experience, and touch in gilding.  Gilding works best when it is fairly humid — at least 50% or higher.

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