Acrylic Paintings: to Varnish or Not to Varnish

Acrylic Paintings: to Varnish or Not to Varnish

newly varnished paintings by Gwen Sylvester

To varnish or not to varnish... Over the last month I've been obsessing about this question.  Using acrylics as my primary painting medium has allowed me to paint as much as I want in a relatively fume-free environment. It's opened up a world of possibilities for me since I gave up the romance of being an oil painter and went over to acrylics. Having to deal with adverse reactions to fumes created from solvents and oil based paints made it impossible for me to produce the amount of work that I wanted and needed to do. The experts at Golden Acrylic Company and museum conservators are now telling me that I should really varnish those lovely acrylic surfaces because they've discovered that acrylics attract dust and dirt and are tricky to clean. One also needs to apply a shiny "isolation coat" of clear acrylic as a buffer to the varnish. Apparently dried acrylics are more porous than oils and could cause problems decades down the line from dirt buildup. 

With a sense of duty and heaviness I bought some spray varnish and some brush on satin varnish in a tin made by Golden. The stuff is made of horrible smelly and toxic compounds... as all varnishes are. It needs thinning with mineral spirits or turpentine... a bummer. I have big reservations over adding the word "varnishing" to my list of tasks.  I've recently been inquiring with acrylic artists and gallery owners about the acrylic/ varnish dilemma . One seasoned artist said that she felt that varnish would ruin the subtle surfaces of her abstract paintings. Another acrylic pro that I talked to said "It depends on the piece". I liked hearing those answers. If varnishing would ruin the look of a painting, then why do it?  Who cares about it looking dusty 100 years from now. On the other hand, I've very recently discovered that varnishing can enhance my work and definitely add to the durability factor. It takes some bravery to brush on coats of (shiny, matte or satin) finish on a painting and risk ruining the look of something that took a great deal of time to create. A bad varnish job can feel like a disaster. At first I spent time experimenting on some paintings that were not my favorites. I do not like spray varnish.. hands down. I'd rather brush it on, then go back in later to fill in areas I've missed by hand. The spray paint delivers a maximum load toxic fumes and seems almost haphazard.

This week I varnished several pieces outdoors, careful that there was little or now wind (or rain). I'm on a learning curve over what products to use and how to apply them in the most health conscious way. So far I'm pleased with the outcome. I wouldn't want to be exposed to those chemicals very often. At the same time I'm setting aside some paintings that I'll probably never varnish so as to not compromise the aesthetics of the surface. Pictured above are some pieces that I recently varnished and framed and I'm glad to say that I like the results so far.

Source:  http://gwensylvester.blogspot.sg/2013/07/acrylic-paintngs-to-varnish-or-not-to.html

What is gesso?

Gesso, pronounced ‘jesso‘, was traditionally used to prepare or prime a surface so Oil paint would adhere to it.
Gesso is the same as a primer, as in ‘pre-primed canvas’.
It is made from a combination of paint pigment, chalk and binder.
Traditional Oil ‘glue gesso’ was made with an animal glue binder, usually rabbit-skin glue, chalk, and white pigment, usually Titanium white.
Gesso is usually white or off white and is used after you have sealed the raw canvas with a coat of size (see: the Trouble with Oil)
It creates a surface that is both absorbent (particularly useful for ‘dead’ colouring with oils) and has a ‘tooth’ (texture) that allows paint to grab onto the surface…

So what is Acrylic Gesso?

Modern acrylic gesso is a combination of calcium carbonate (chalk) with an acrylic polymer medium (binder), a pigment (titanium white) and other chemicals that ensure flexibility, and ensure long archival life.
Why do I need to use a gesso primer for Acrylic painting?
Technically you don’t. But in practice painting directly onto a raw canvas is not an enjoyable experience. Unless you are interested in deep staining effects like Morris Louis
 who became fascinated with using diluted acrylic paint to stain the raw canvas, rather than apply with a brush.

Alpha-Pi, 1960
Morris Louis (American, 1912–1962)
Acrylic on canvas

Can I use acrylic gesso under an oil painting?

Yes and no.
Yes for 90% of your paintings especially if your just beginning ‘acrylic gesso‘ will be fine if the raw canvas has been properly sized, thus protecting the canvas from the corrosive nature of oil.
However, if it was for a portrait or to produce a masterpiece for your painting legacy I would use an Oil gesso purely for the fact it has been time tested and the Oil will always adhere better to Oil than sitting on top of an Acrylic.
Pro tip: If you want the first layer of paint to dry quicker than it normally might, just add gesso. The gesso primer layer can soak up the oil from within the paint and leave a ‘dead’ flat under painting that won’t have any sheen to it. Imagine the difference between painting onto glass and painting onto blotting paper. All the oil from the paint would be absorbed into the primer layer.

Do I need to buy it?

Homemade or ready made?
Shop bought gesso comes pre-prepared in tubs or tubes and is pretty good, homemade gesso is cheaper to produce and can be adjusted to personal needs and tastes, however,  it’s not needed when you are first starting painting.
Artist or Student quality?
As with paints, the difference between the two is dependent on price. The artist quality having a higher price, more pigment and a higher opacity. The student quality will have a lower quantity of pigment and more filler. If you are painting onto a raw canvas the artist quality would be best due to the increased opacity. For adding a bit more absorbency to a pre-primed canvas student quality would be fine (you can always add a bit more white pigment to it).
Can I colour the gesso?
Yes, I am a big fan of working on a coloured ground and if you are pushed for time you can mix some paint into the gesso to tint it. You can also buy premixed black gesso, coloured gesso and clear gesso.
Pre-primed canvas boards
“Pre-primed“  means “pre-gesso” It already has a gesso layer applied in the factory. On the cheaper ranges for some reason manufacturers often use a seal on top which creates a shiny surface which is completely ridiculous… defeating the object of gesso!
If you are using watered down paint or student quality paints the shiny surface can repel the paint. The more watery the paint the easily it will sit on the surface and not soak into the canvas as you would like.
If you apply a couple of coats of gesso it will form a more absorbent surface due to the chalk (calcium carbonate- known as ‘whiting’ in oil painting) found in the gesso.
Creating a super smooth finish
You can sand gesso between coats to create a lovely smooth finish, especially handy for photo-realistic paintings, just sand each layer with a fine sandpaper. Say a 240 grit. 3M’s make a good sandpaper. Just make sure you do it outside, or in a well ventilated area as it goes everywhere!

How to gesso a raw canvas for acrylic painting

What You Need:

• Gesso
• Decorators brush
• Kitchen Roll
• 240 grit sandpaper if you want to sand the layers in between each other.

1. Buy a tub of premixed white gesso and give it a stir. Again, this really comes down to personal preference, I work from a tub so I can control the amount of gesso on my brush for each stroke but you can buy it in tubes.
2. The first coat always needs to be diluted with a touch of water (sometimes people recommend adding a bit of acrylic medium to prevent cracking but the layer is so thin and soaks straight in, it would never crack).
3. Allow to dry, then apply a second coat. This can be applied thinly and does not be watered down. If you want a more absorbent surface, add another layer.
4. When applying the gesso turn the canvas 90 degrees between coats to insure an even coverage.
5. Apply a final coat using the pure, undiluted gesso.
6. Using a 3 inch decorators brush, apply the gesso directly to the stretched canvas in even strokes. Work from the top to the bottom of the canvas, in parallel strokes from one edge to the other.
7. Wash your brush out immediately in running water then use a brush cleaner to thoroughly remove the gesso out. It’s worth cleaning it twice even if you think it’s clean.

Pro tip: Golden paints make a hard gesso that can be useful if you are working on a board. Due to the limited movement on a board compared with a canvas it can create a smoother finish.

Source:  http://willkempartschool.com/how-to-prime-a-canvas-with-gesso-for-an-acrylic-painting/

Rainbow Rain Art

How and when to Use Gesso in Acrylic Painting

Most painters who use gesso in their paintings typically use it as a staging medium based upon what they are going to paint on the canvas if they have predetermined what the image will be in their acrylic painting. Gesso is basically a primer that prepares the canvas for acrylic, gauche, oil or watercolor paints. Therefore, when using gesso in acrylic paintings, it can be used as a primer or mixed with the paints, or both. When using gesso with paints, it may be necessary to use a drying retarder to keep the acrylic paints from drying out too soon. Gesso has been around for centuries, and has been a staple for many artists in many types of media. White gesso is the most commonly used gesso in acrylic paintings, but not the only one available these days. Black, dark and light gray are the other colors most readily available in gesso for acrylic paintings. A painting that will have light colors throughout most of it would be best to have a layer of white gesso on the canvas or board before painting.

Another type of gesso that is forgotten about is the clear gesso. This gesso can be used directly with paints as it will not change their color as any of the other types of gesso will do so. Clear gesso allows the paint to stay wet a little while longer and helps to thin the paint better than using water. Adding too much clear gesso is the same as adding too much water. The paint will slide down the canvas or board all too easily if it is not missed correctly.

Mixing clear gesso with drying retarder will allow the paint to not dry so fast so that the artist can come back to the acrylic painting as they would with an oil painting. Although this is not a common practice it does, however, lend a helping hand to an acrylic artist who has many projects on the 'back burner."
Gesso does not have to be used in an acrylic painting if the canvas or board to be painted upon is pre-primed when purchased. Acrylic paints do not even need to be diluted unless the artist feels the need for it.

The darker colored gessoes will darken the paints used when missed with them. As with any type of art, much practice and pre-planning is involved when using this method of painting. Artists who are just starting out in this type of painting method tend to paint on inexpensive boards and canvas pads.
Gesso can be found in art stores around the world. Some of the more sought after brands are Matisse, Liquitex, and Winsor & Newton. Before purchasing gesso for your nest acrylic painting, ask yourself what purpose are you going to use it. This will determine how much you will need and which type as well.

source: http://voices.yahoo.com/how-gesso-acrylic-painting-5206089.html