Paint is created by combining dry pigment and liquid. In oil paints, the liquid used is linseed oil. You purchase oil paint in tubes. The paint is thick. So when you squeeze it out onto your palette, you mix it with your palette knife and use a stiff brush to apply it to your canvas. The thickness and composition of the paint means that it is very slow drying. Paintings done in oil typically take around 72 hours to dry.
The upside of the delayed drying time is that you can make adjustments to refine your painting. This can be done for up to twelve hours after you paint the canvas. You can make gradual shifts from one color to another. If you are using oil paints, you can also completely remove things from your canvas with your palette knife or a wet rag. Once the paint has dried completely, you can then put new colors on top of the original layer of paints. However, be aware that in order to avoid cracking, each subsequent layer must be thicker than the previous.
The drawback of using oil paints is that when you paint one color next to another on your canvas, they taint one another easily.
To begin an oil painting, you need to sketch your subject onto the canvas. You can use thinned paint or a piece of charcoal to accomplish this. However, if you use charcoal then it must be sprayed with fixative in order to isolate it from the colors. That is an advantage to using paint to sketch the subject is that you do not need fixative. Sometimes people transfer drawings onto the canvas. A drawing on thin tracing paper is taped onto the canvas. Carbon paper is then used to transfer the drawing. Trace over the drawing with the carbon paper positioned underneath it. A ballpoint pen will enable you to see where you have already traced. Once you are finished, fixative is necessary to isolate it from the paint.
Brushes are used to apply the paint to the canvas. The brush is the most vital tool an artist has. One of the markers of a talented artist is difficulty painting with poor quality brushes. You want a brush that maintains its shape even when loaded down with paint. At the conclusion of each stroke, the brush will return to its original shape. Brushes come in either sable or bristle, which is from pigs. Bristle brushes are appropriate for large areas on the canvas. Sable brushes are best for smaller areas and detail work. Brushes for oil paints come in flats, filberts, brights, or rounds. Flats are the most versatile brushes, used for a variety of strokes and blending. Filberts make a stronger edge. Brights allow your brush strokes to show. Rounds are for detail work.
Typically, you will paint with oils in layers. The first layer is the underpinning of the painting. Typically, these are just the values blocked out in paint