Making gesso

The acrylic primer on pre­pared can­vases or avail­able in stores is usu­ally labeled “gesso.” It’s not actu­ally gesso and man­u­fac­tur­ers shouldn’t call it that. For oil paint­ing, I find real gesso to be a much bet­ter sur­face than acrylic primer. Egg tem­pera and tem­pera grassa should be used only with real gesso pan­els. Gesso should only be used on inflex­i­ble sup­ports (i.e., pan­els), because it is too brit­tle for can­vas and will crack.

Ges­so­ing is easy and almost fool­proof, but time-consuming. It takes an after­noon to gesso a panel. On the other hand, it takes an after­noon to gesso five, ten, or twenty pan­els, so it pays to pro­duce them in vol­ume. I gen­er­ally invest three or four after­noons a year in mak­ing enough pan­els to pro­vide me with a steady supply.

Here’s how to make and apply gesso:

Mate­ri­als

Hide glue (often labeled “rab­bit­skin glue” whether it con­tains any rab­bit or not). Most major art sup­pli­ers have this.

Inert white pig­ment. This is pow­dered chalk or gyp­sum. The mar­ble dust you can buy in art stores is chalk. Plas­ter of Paris is cooked (anhy­drous) gyp­sum, but I have found it too gritty to make good gesso. (The word “gesso” means “gyp­sum” in Ital­ian, since that’s what Ital­ians made gesso from. In North­ern Europe, chalk was the tra­di­tional mate­r­ial). You can buy good-quality pow­dered gyp­sum from spe­cialty sup­pli­ers like Kre­mer.

Tita­nium white pig­ment. This is optional. Some peo­ple like to sub­sti­tute up to 20% of the inert white pig­ment in the recipe below with tita­nium white, for bright­ness. I haven’t found it worth the bother.

Panel. There are var­i­ous mate­ri­als you can use for panel paint­ing. One good option is to buy hard­board at the home improve­ment or hard­ware store. You can buy it cheaply in 4 foot by 8 foot sheets. Get tem­pered hard­board 1/4 inch thick. The staff at the store will prob­a­bly cut it to size for you if you ask. Other mate­ri­als you can use for panel include medium den­sity fiber­board (MDF) and actual wood planks. Wood pan­els of any size, how­ever, are best sea­soned for 1–3 years, with plan­ing to size if it warps, after it has been cut to final size.

Wide flat brush. A good house paint­ing brush will do.

A dou­ble boiler. I don’t like com­mer­cial dou­ble boil­ers because there is too much con­tact between the metal pans. Instead, I use a pair of very cheap pans—one small, one large. I use an empty tuna can to sup­port the small pan in the large pan.

Mea­sur­ing spoons, mix­ing spoons.

Sand­pa­per. Sev­eral grits.

Prepar­ing hide glue

Make the hide glue the day before you plan to gesso the panel. Hide glue nor­mally comes in pow­der or gran­u­lar form. Mix one part hide glue with 11 parts warm tap water. One cup makes about enough to size and gesso two 8 × 10” pan­els, depend­ing on how many lay­ers of gesso you apply. Stir the water/glue mix­ture for about five min­utes, then let it sit for 6–24 hours or so. It will form a thick gelatin. If the weather is very hot (95 degrees Fahren­heit+), it might not gel prop­erly unless you put it in the refrigerator.

Prepar­ing and siz­ing the panel

The edges of the panel should be smoothed with sand­pa­per or a rasp. Clean the panel with dena­tured alco­hol to remove any trace of oil or other guck.

Now you want to coat the panel in a layer of hide glue. This is called siz­ing the panel because another word for hide glue is “size.” You’ll start by warm­ing the glue to make it fluid. If you heat the glue too much, it will weaken the glue. As it turns out, hot tap water is about the right tem­per­a­ture to liq­uefy glue with­out dam­ag­ing it. So fill the outer pan of your dou­ble boiler with hot tap water and put the glue into the inner pan. In about ten min­utes, it will be about the con­sis­tency of milk (whole milk, not that low fat stuff). Brush the glue over the front, back, and sides of the panel. Give it a half hour to dry.

I gen­er­ally add more lay­ers of glue to the back. The rea­son is that the glue in the gesso on the front will be apply­ing force to the panel. If the panel is large, this will notice­ably warp the panel. So I gen­er­ally add about four lay­ers of glue to the back in order to coun­ter­act the warp­ing effect that the gesso will apply to the front. This seems to help a lot.

Mak­ing gesso

Mea­sure the vol­ume of the remain­ing glue and pour it back into the dou­ble boiler. You will be adding 1.5 times this vol­ume of chalk or gyp­sum to make gesso. Do this grad­u­ally, gen­tly drop­ping each spoon­ful into the liq­uid to avoid mak­ing any bub­bles. Dis­trib­ute the chalk/gypsum around the pan so that it the glue soaks into it. Once all of the chalk/gypsum is in the pot, give it 10 min­utes to soak. Now take a brush and gen­tly stir the mix­ture, again try­ing to avoid mak­ing any bubbles.

Apply­ing the first layer of gesso

For the first layer, spread it thinly over the sur­face of the panel, stroking back and forth in one direc­tion. It’s not very opaque when wet. Let it dry; this takes 10–30 min­utes, depend­ing on humid­ity and tem­per­a­ture (dry days are best for ges­so­ing pan­els). You’ll know it’s dry when it feels dry to the touch and any gray­ish areas have dis­ap­peared. Cen­nino, a 15^th cen­tury Ital­ian artist and writer, sug­gested rub­bing the first layer in with your hand rather than spread­ing with a brush. That’s messy, but works just fine and may improve adhesion.

If the gesso in your pan is get­ting thick, it means that it’s cool­ing off. Replace the water in the dou­ble boiler with new hot tap water. Don’t overdo it; this is usu­ally nec­es­sary only once every 30–60 min­utes or so.

Apply­ing the rest of the gesso

You will apply 6–8 lay­ers of gesso. Brush strokes in each layer should be applied at right angles to those of the pre­vi­ous layer. Each layer is best applied shortly after the pre­vi­ous layer has become dry. It’s best to apply all lay­ers in one day, so that they will bond with each other. If you get crack­ing, that means that you’re apply­ing the gesso before the pre­vi­ous layer has dried. More lay­ers will fix this. If you get lit­tle pits in the gesso, then you’re paint­ing with gesso that has bub­bles in it. Let the gesso stand for a half hour before apply­ing any more, then rub the next layer in with your hand.

Once you’ve applied all the gesso, let the panel dry for at least three days. You can clean the brush, pan, and any­thing else that got gesso on it in warm water.

Smooth­ing the panel

Start by using a metal file to cham­fer all of the edges of the gesso, so that they are at a beveled angle inward. This pro­tects against crack­ing, should the panel strike some­thing (I’ve had this hap­pen with a large panel that I put a lot of work into, and it’s very irritating).

To get the panel smooth, I like to use a sand­ing block, start­ing with 400 grit sand­pa­per and mov­ing to finer grits at the end. This pro­duces a beau­ti­ful, eggshell-smooth fin­ish that is almost too beau­ti­ful to paint on.

If I’m going to be paint­ing with oil, I like to apply a final layer of hide glue to the smoothed sur­face of the panel. With­out that, the gesso is a bit too absorbent. Oth­ers use a thin layer of shel­lac or var­nish to reduce absorbency; I haven’t tried that.

For egg tem­pera or tem­pera grassa, plain gesso works great.