Oil painting is the process of painting with pigments with a medium of drying oil as the binder. The choice of oil imparts a range of properties to the oil paint, such as the amount of yellowing or drying time. Certain differences, depending on the oil, are also visible in the sheen of the paints. An artist might use several different oils in the same painting depending on specific pigments and effects desired. The paints themselves also develop a particular consistency depending on the medium. Oil paint is made by mixing pigments of colors with an oil medium. Different colors are made, or purchased premixed, before painting begins, but further shades of color are usually obtained by mixing small quantities together as the painting process is underway. An artist's palette, traditionally a thin wood board held in the hand, is used for holding and mixing paints of different colors. Most oil painters paint in layers known as "glazes", a method also simply called "indirect painting".
The main advantages of oil paints are their flexibility and depth of colour. They can be applied in many different ways, from thin glazes diluted with turpentine to dense thick impasto. Because it is slow to dry, artists can continue working the paint for much longer than other types of paint. This provides greater opportunity for blending and layering. Oils also allow the artist to create greater richness of colour as well as a wide range of tonal transitions and shades.
Acrylic paint is a fast-drying paint made of pigment suspended in acrylic polymer emulsion. Acrylic paints are water-soluble, but become water-resistant when dry. Depending on how much the paint is diluted with water, or modified with acrylic gels, media, or pastes, the finished acrylic painting can resemble a watercolor or an oil painting, or have its own unique characteristics not attainable with other media. If you like the idea of using a palette knife and creating thick, impasto paintings, acrylics could be the choice for you. You can paint thickly, build it up and the paint will dry. If you try to achieve the same with oils the outer surface will dry to the touch but the inner paint will still be wet. You can also work very thinly with transparent glazes or very thickly with a mountain of paint but the actual surface quality of the acrylic remains flexible, this means your painting won’t crack over time.Thin coats of acrylic paint can be used to give a watercolour look to a picture.