Art Session and Gesso

The first session of the year for Art in the studio I tend to share the real fundamentals of drawing, painting, art materials and brushes etc This year it is 'Gesso'and I am adding the element of Mixed Media Backgrounds using different medias including collage.

This session was all about  'Gesso'.

"Gesso", or "Italian gesso"^[,is a traditional mix of an animal glue, a binder (usually made from animal skin).  chalk (an abrasive ground) and white pigment (paint), used to coat, prime or seal surfaces such as wooden panels, a canvas or a paper surface which are absorbent. This allows the painting media to bond to the canvas.
The colour of gesso is usually white or off-white. Its absorbency makes it work with all painting media, including water-based paints, different types of tempera and oil paint. It is also used as a base on three-dimensional surfaces for the application of paint or gold leaf. 
Mixing and applying it is an art form in itself since it is usually applied in 6 or more extremely thin layers, making sure no ridges are formed with the brush strokes. Brush one way across the canvas with the first layer allow to dry then go the other way of the canvas for the next. Ensure all the surfaces, sides are covered and the back of the canvas where it is stretched over, this can often be forgotten. I always start with the sides and back of the canvas then the front, this stops any ridges forming on the front while painting the sides. Allow each layer to dry thoroughly between painting. Some well known painters would have apprentices do the initial priming process  and then would prime the last layers often leaving days or weeks for drying time between each layer, allowing for curing. 
The amount of layers are up to you especially if you have a good quality of gesso and are time dependent. 
Reason for the glue is flexible and is added to allow bonding of layers and prevents cracking, this makes it suitable for rigid surfaces. Although animal glue was often use to 'size' a fabric canvas. it allows moisture to be absorbed so can lead to cracking too, this has been found of time and history. So we use a pva based glue which does not respond to moisture in the air but allows flexibility.Shop brought Acrylic Gesso does this for you. It is expensive and this is why I make my own.

The better your surface preparation the longer your painting will last.

For priming flexible canvas for oil painting, those made from fabric, an emulsion of gesso and  a few drops of linseed oil, called "half-chalk ground", is used to ensure flexibility in the canvas,help to prevent cracking and the acid in the oil paints from rotting the fibres of the canvas.
  
Gesso is also great for recycling canvases or panels. Some may need sanding down to smooth the paint surface down or if you want the brush strokes and paint mounds you can just paint gesso over the top.
I often do this by using one or more layers of Gesso (allow to dry) then collaging the surface then using gesso over the top and then painting, this allows for a textured surface at the beginning of your painting.
After you have primed a few layers you can use the gesso to etch into if you want added texture or add areas of gesso that you have applied with tools other than brushes.

Many of the store brought canvases have a plastic 'feel' surface to them, they have been primed but that is to prepare them for sale and so they do not get damaged so easily. You will still need to prime or seal the surface otherwise many paints will 'smear off' or the first layer of paint that you apply will soak straight in. This is why it is often advised to add your ground layer of paint first so it soaks in and covers the 'white' surface.

My Gesso Recipes

A combination of recipes that I have tried and tested over the years that work.
Using,
Talcum Powder or
Fine White Plaster
either, Household White Emulsion Paint or White Acrylic Paint
and good quality PVA or wood glue. 

The better quality of ingredients the better the surface and less likely to crack.

 Plaster Mix

1 cup of Water

1 cup of Glue

2 cups of White Acrylic Paint

4 Tablespoons of Fine White Plaster

Mix the Water, Acrylic Paint, Glue and then the Plaster really well.

Put into a sealable container that is labelled with Gesso Type.

*Some times you may need to sieve the plaster mix if you find lumps appearing in the mix.

To make an Emulsion Mix exchange the Acrylic Paint for Household Emulsion.

Talcum Powder Mix

1 cup of Water

1 cup of Glue

2 cups of White Acrylic Paint

4 Tablespoons of Talcum Powder

Mix the Water, Acrylic Paint, Glue and then the Talcum Powder really well.

Put into a sealable container that is labelled with Gesso Type.

To make an Emulsion Mix exchange the Acrylic Paint for Household

Emulsion.

These recipes then get diluted with water to the consistency you require depending on whether the painting has fine detail or not. The more thin layers of Gesso the better and if you wish you can lightly sand down between layers to make it even smoother using fine grade sand paper.
This preparation to your surface enables you to get fine brush detail with your paints.

Gesso can go 'off' a mould forms on the top once opened. I make enough for what I need so do not worry that I may need t throw a small amount away.
I have been known to rescue a moulded gesso by skimming off the top layers of mould and then using it. I have only used it on my leisure painting and
would always have it in my head that my professional painting may start to change if I used the damaged gesso on it, so if in doubt chuck it out.

Watch our mixing video on our Facebook Page The Old Art Room  HERE