How to Varnish a Oil Painting

Have you ever asked yourself how to varnish a oil painting? I know it seems a trivial question but it is not! It may sound simple and obvious to varnish a painting,someone may think,but that’s not the case. In fact it is not enough to grab a brush and a little varnish and applying it over the surface of painting,actually thinghs are more complex!

In this post i will explain you how to varnish correctly a oil painting,what varnish should be used as well as what are the best brushes for this important task.

First and foremost we must make a premise: you can’t varnish oil paintings without knowing simple but essiential rules. One must bear in mind that oil painting needs a minumum of six months to be considered dry and therefore ready to be varnished. In so called thickness paintings,better known as “impasto paintings “,drying times will increase even more and you should wait at least one entire year before applying final varnish! 

If you do not wait for long drying times of oil colours  and you go in a hurry, you may ruin irreparably a painting that perhaps took several months of work! 

Well once you understand the importance to be able to wait long drying times of oil colours in order to varnish a oil painting let’s go to discover what kind of varnishes we can find on the market.There are two categories of varnishes: varnishes from natural resins  and varnishes from synthetic resins.

Varnishes from natural resins are composed by resins of animal and vegetable origin as well as fossil. Generally resins of vegetable origin are carved out of trunks incisions of various plants and trees. Fossil resins such as those copals are extracted from young fossil amber and therefore they can be considered subfossil resins. Such resins are extracted in different parts of the world from different species of trees and they are used to create varnishes and solvents. Damar’s resin also called Kauri is pulled out both from fossil plants and living ones and it is soluble in a mixture of ethyl alcohol and ether. Schellac however is a resin of animal origin and is obtained  from a small parasitic insect. Shellac is soluble in alcohol and alkalis and creates a film of high resistence, brilliance and elasticity.  

Varnishes from synthetic resins are composed mostly from a variety of polymers that look alike to vegetable resin. The most used synthetic resins are phenolic resin,acrylic,epoxy,vinylester and unsatured polyester resins. Synthetic resins have a great durability as well as excellent elasticity and good reversibility.

Now we have made it clear two different categories of varnishes on the market,let’s see what to choose for our oil paintings. Main varnishes from natural resins are:

-Damar Varnish

-Copal Varnish

-Mastic Varnish

While main varnishes from synthetic resins are:

-Final Brilliant Varnish

-Final Matt Varnish

-Final Satin Varnish

-Final Superfine Varnish

We can notice that there is no lack of choice ;the issue is that we need to know features of different varnishes in order to adapt them to our needs. Now we’ll analyze main features of varnishes and we’ll see what are better suited to oil paintings.

Varnishes from natural resin are great varnishes resistant to ageing ,elastic and resistant even to cracking.They provide a good light protection as well as to atmospheric agents; moreover they can be dilute with turpentine to make them more flowing.Until now such categories of varnishes would seem perfect for final coating of oil painting but it has two weaknesses not insignificant.

-The first flaw lie in the difficulty to remove the varnish after a certain period of time. As all things even varnishes are not eternal and after a certain numbers of years they should be removed in order to apply other new layers. 

–The second flaw lies in the fact that all varnishes from natural resin tend more or less to yellowing! Nobody would like to have a yellowed painting also because it would ruin the final effect of artwork!

Varnishes from synthetic resin  have no weakness of  natural resin therefore they do not turn yellow during the time  and moreover they are easy to remove.

–Final Brilliant Varnish: This kind of varnish is suitable for oil colours as well as acrylic ones. It creates a soft and resistance film which do not turn  yellow over the time. It dries in a few hours and it resist quite well to humidity. 

-Final Matt Varnish: This kind of varnish presents characteristics similar to brilliant varnish with the only difference that once dried it unifies painting opaquely making less brilliant oil colours!

-Final Satin Varnish: This kind of varnish has a perfect brilliance since does not reflect excessively and it has a optimal transparency. As all synthetic varnishes it is elastic,uniform, easy to remove, moreover it does not crack and not yellowing as well. It protects the colours from atmospheric agents as well as from dust and light guaranteeing long life to painting.

-Final Superfine Varnish: This kind of varnish presents characteristics similar to varnishes aforementioned with the difference that once dried makes painting shiny and not excessively brilliant.

  All these varnishes have common features as quick drying,easy removability,not yellowing and they can be dilute with turpentine or white spirit.It is not enough to have a good varnish to uniform painting but as you can guess it is necessary to have a good paintbrush which reflects specific features.

Choosing paintbrushes to varnish oil paintings may sound easy but it is not at all! These special brushes should have certain peculiarities so they can be used to varnish oil paintings properly. First of all a good brush suited to varnish of painting should have a short handle and moreover it should be flat and wide. It furthermore should be composed of soft and short bristels. They should be preferably synthetic since they are more resistant to corrosivity of varnish! Perfect brush should have also a good grip as well as guarantee a smooth brush stroke. Well now we know what varnishes we can use  and what kind of brushes to buy, let’s see how to varnish a oil painting.

Before varnishing a oil painting we need to ensure that surface is ready to receive the layer of varnish. We need to wait for at least six months to be sure to varnish without problems. Being so patient we will proceed in this way:

We have to carefully lay canvas on a hard surface as can be a table making sure it is well-cleaned,without any dirt or dust. However before preparing varnish we need to remove dirt and dust which have accumulated on a surface of painting.How to do? You just have to take a cotton ball ,soak it in the water but not too much and delicately pass it all over the paint surface as long as all the dust and dirt will be removed. After is left to dry painting for about ten minutes we will proceed to prepare varnish. You pour varnish in a bowl large and clean and afterwards it must be dilute with 20% of white spirit. Someone prefer to use turpentine but i find it too strong and aggressive so much that if you make a misteke with the dosage it could ruin the painting! White spirit serves to dilute varnish, make it lighter and smoother  so as to facilitate applying as well as let it dry more quickly. After diluting carefully varnish with white spirit we grab a paintbrush wide and flat and we soak it into the varnish without overdoing it,indeed we need to ensure that varnish doesn’t drip on painting. After doing this we need to apply the first coats of varnish vertically always in the same direction and without insisting in the same point. When painting is completely varnished you can immediately notice first beneficial effects of varnish,above all smooth and brilliant tonalities ,as if they were just painted! After the first coat we need to wait for about one hour in order to allow to dry varnish perfectly and we will apply the second and final coat of varnish horizontally. After this last task you let it dry as long as you can consider painting perfectly varnished and ready for sale. Varnished painting is more attractive for eventual buyers since it appears without opaque areas and with the right brightness,therefore perfectly smooth with vivid and intense colours!

Remember to clean paintbrush with white spirit otherwise varnish will make it unusable for next varnishing and you’ll have to throw it away!    

The last advice i can give you is that you do not want to use,for istance,a varnish too brilliant or too matt,you can mix them up without problems to adapt them to your needs,indeed all varnishes from synthetic resins can be mixed with one another. Well let me conclude now hoping that this article can help anyone who has had problems with varnishing of oil paintings.