I got a message on Facebook from a friend the other day asking this very question. I tried my best to answer her question with as much knowledge as I could without having her confused, and to my delight, it seemed to work. I am a “Trial and Error” artist meaning, like many artists, I tend to learn by using and making mistakes then “try” to learn from those mistakes. I was very surprised that she actually messaged me of all people to find out what Gesso was, and it was used for, and afterward I got to thinking “What is “Gesso”?, and what is it really used for?
The word “Gesso” or “Glue Gesso” comes from the Italian word Gypsum (which is one of the minerals that it is made from). Gypsum is also used in many forms of plaster (plaster of Paris), blackboard chalk, and its the main ingredient of drywall boards and drywall compound.
Today many people use a black or white acrylic Gesso as a primer for their linen canvas and wooden panels, or an underpainting with acrylic paint, but it has many more uses, and comes in several forms. You can find a clear Gesso, and it can also be found in several other colors.
Before getting into some more uses of Gesso I want to give you some information on the various types of Gesso. The 1st and most often used is “Acrylic” or “Modern” Gesso which is made with:
- – a calcium carbonate (Chalk, Gypsum, or Limestone)
- -polymer medium latex
- – pigment (Titanium White)
- -other chemicals to ensure flexibility and long lasting life
Technically “Acrylic” or “Modern” Gesso is not really “Gesso” at all. It is more of a hardener that covers the surface to keep paint from actually soaking into the surface, not unlike a primer you use on bedroom walls. Acrylic paint is noncorrosive and holds its stability over time, so it doesn’t need glue like traditional Gesso. It is also worth noting that some oil paints have been known to “release” or delaminate from acrylic gesso.
To help with the issues of delamination or the “release” of oil paints from the gesso primed surface, there has been a remedy in “Soy-based Gesso”. Recently introduced into the market, Soy-based Gesso is a low-emitting, bio-based Gesso made from recycled soy content, and is eco-friendly. It uses a binder of a soy ester and a thin film of a modified acrylic. While it’s very similar to an Acrylic Gesso, the penetration of the oil from the soy to adhere to the surface, it allows a physical bond between the oil paint and the gesso and is more resistant to cracking.
Third and oldest type is “Traditional” Gesso or also referred to as “Italian Gesso” made with:
- an animal glue binder
- chalk (gypsum, limestone)
- white pigment
Traditional Gesso was used to coat surfaces like wood, and canvas panels. The Gesso would coat the surface and reduced the amount of paint used while giving it a truer, more vibrant color. It could be used with any type of paint medium used at the time, including water-based paints. Gesso would also leave a rougher surface or “Tooth”, that helped the paint to adhere. While Traditional Gesso was great for more rigid wood surfaces, it would cause paint to crack when applied to a flexible linen type canvas that could be rolled up.
Today you can buy pre-primed canvases which are coated with a thin layer of gesso. You can also add another layer for added security or if you have a raw canvas, or a canvas you stretched yourself, here is a quick step-by-step to priming your canvas with gesso.
- your painting surface (raw canvas, wood panel, heavyweight paper, etc)
- primer for your surface ( acrylic gesso, absorbent gesso, etc)
- a wide gesso brush (any wide brush with soft bristles will work)
Step 1: Make sure your area is clear of anything you don’t want to get paint on. Take your surface and lay it flat, and examine it to make sure it is clean and free of dirt or oils. A good wipe down with a paper towel or clean painter’s rag. If you find any oil residue of any kind, you can use an artist grade degreaser or a spray bottle with rubbing alcohol will work also.
Step 2: Most kinds of Gesso are ready to use straight out of the container. I like to apply several, very thin, coats. It’s not required, but that is just me. I do advise to at least do 2 good coats to make sure you have a very good cover. I take a paper plate (acrylic gesso) or plastic bowl (oil based primer) and mix my thinner (water for acrylic gesso, mineral spirits or orderless thinner for oil).
Step 3: Take your brush and dip it into the gesso and apply an even coat to the surface. Keeping your gesso thin and building it up slowly helps to not get puddles and helps with drying time. Keep you paint strokes going in the same direction as best as you can. It will allow for a more even layer.
Step 4: Allow this coat to dry completely! If you are using Acrylic gesso you can use a hair dryer to help speed up the process. after it dries you will want to use 100-110 grit sand paper to light smooth out any rough spots (also why I like to do very thin coats). Don’t sand to a very smooth surface!! You will want to leave a slight “tooth” to your surface.
Step 5: Apply your next layer the same as Step 3 except going in the other direction. If you did it horizontally on the first coat, do it vertically this time. Repeat steps 3 and 4 until you feel satisfied that your surface is covered adequately alternating your brush strokes each time and providing some light sanding each time. I usually do up to 10 thin coats (especially for oils but that is not required.
There are several kinds of gesso made by even more brands. I have my favorites, and with time and opportunity, you will find yours also. I hope you found this article helpful. Please leave a comment and any questions you may have, and please if you have anything to add that I may have missed please let me know. I will be doing another blog with some more uses of gesso that I hope you will find fun and creative. If you have any ideas for projects to do with Gesso please leave me a message on here or email me at firstname.lastname@example.org . Until next time Keep Inspiring, Keep Creating!