Oil paintings can be very hard-wearing; there are examples available of more than 500 years old oil paintings! But it’s not the paint itself that’s durable – it’s the specific way you apply it. Tubes of oil paint are raw ingredients. If you layer them incorrectly your painting will crumble and fall apart within a few years after completion. There are three major rules that make a oil paintings last the ages:
• Paint fat over lean oil paint
• Paint thick over thin oil paint
• Always use fresh oil paint
Fat over Lean Oil Paintings
The rule “fat over lean” means that every following layer of oil paint has to be just a little bit fatter than the preceding one. In the first layer, you just paint with oil paints right out of the tube, and you make them thinner with turpentine. In the second layer, you add just a little bit of painting medium to the paint. In the third layer, you add a little bit more of medium to the paint etc. Oil painting medium can be prepared with stand oil and dammar varnish, mixed in equal amounts.
Thick Over Thin Oil Paintings
Thick layers of oil paint will take a longer time to dry than thin layers of oil paint. The drying process of oil paint doesn’t end when the paint is dry to the touch. And every time you paint a layer over that, it will form a layer. Thick film dries more slowly than thin films of oil paint. Faster drying film layers shrink faster than slower drying film layers. So, a thin layer of film painted over a thicker one, will crack in time. In oil painting, it is better to first work with thinner washes, merely coloring the surface, and includes texture later.
Oil paint forms a film when it dries. It dries in contact with oxygen. When the oil paint has already been exposed to air for more than a few hours (on your palette), you can still stir it and it may seem like you can still paint with it. But it the quality of film will decrease. When oil paint has partially dried, its ability to make one solid film is distorted, and it will peel off over time – long enough to fool you, but not long enough to satisfy the buyer of the painting. If you want to preserve leftovers of paint, carefully cover them with plastic foil and use them as soon as possible.
Oil Painting Durability
Durability depends a lot on the painting grounds you use. Canvas is supple, and dried gesso is much less flexible. There’s no record of the way oil paint behaves after a hundred years on gesso, because gesso is an acrylic material! It has only been there for a few decades. But it is believed that in time, the oil and gesso will separate from each other. We all know that acrylic and oil paint are two very different materials and even only because of the stiffness, gessoed canvases tend to crack in time.
You can avoid this cracking by gessoing your own canvases and adding some caseine to the gesso (or adding a thin layer of gesso to a ready-primed canvas). Caseine makes the gesso more elastic, and it aids the oil paint sticking on to the gesso. This is also a good reason to add caseine to the gesso when you set up a painting board.
When you glue your canvases the old fashioned way with hide-glue, make sure to use very, very thin glue. A too thick hide-glue layer causes problems (circle-shaped cracks). The same goes for acrylic binder (not too thick under layers, only a thin sizing to impermeate the canvas)
Most 20 century art will be gone in 50 years, owing to bad painting techniques. It will only be obtainable as a digital reproduction… Such problems really are preventable.
Where to Find Quality Oil Paintings for Sale
There are many oil painters who sell oil paintings for affordable prices. Whether or not their oil paintings will be around in 50 years is another matter altogether. That is why it is important that you purchase oil paintings from qualified artists who use the best quality oil paints and oil painting techniques. This way you will be able to keep your oil paintings and pass them from generation to generation!