There are many arguments for and against varnishing a painting. What is it exactly? Varnishing refers to the final layer which is applied on a painting once it is completed and it is where you actually declare that you are done with the painting and no further changes or modifications are involved.
Varnish is applied when a painting will be displayed on the stretched canvas and there is no need for them to be framed and such. This is because varnish is able to protect the painting from dirt, dust while it is also known to homogenizes the final piece of work. Essentially, what this does is that it evens out the appearance, very much like creating a ‘flattening’ effect.
There are generally 2 types of varnishes most commonly used by artists known as gloss and matte varnishes. Where this is concerned, gloss varnishes usually dry completely transparent which means that the original image is kept as it is.
On the other hand, matte varnish or satin varnish usually create a filter above the artwork. This is sometimes done intentionally by the artist as it is what they want to express. The translucent filter gives it a frosted-glass effect which might not be so favoured if the painting has a lot of details.
In most cases, varnishes used for acrylic paint are water or solvent based which means that they could be removed if needed although it is not an encouraged practice. Ideally, varnish should be removable if needed.
To varnish your painting, you must ensure that the work is completely dry. This is of course easier if you are using acrylic paint instead of oil, which takes a longer time to dry. It is something that needs to be done very patiently because you want to create an even flow of impression here.
The best method to do this is by using sponge-brushes or flat-brushes because they create the evenness in the texture when applied. Before starting out to varnish, wipe the surface with a micro-fibre cloth so that there are no dust and it is clean.
One thing for sure, before applying the varnish, ensure that your painting is completely complete. This means that you have applied the last drop of paint and that you have already signed the painting because once you have applied the varnish, there is no turning back.
After that, apply the varnish on the surface. Where possible, ensure that you only cover a particular surface once and then move on until you have covered the entire canvas. You must try to cover every inch of the canvas and it gets tricky because the varnish is transparent. Once you have done that, leave the painting for a while so that the varnish dries.
Do not try to conduct any touch-ups and if there are any spots that you have left out, you can cover them when you apply the second layer. Ideally, you should apply 3 layers so that all the areas are covered.