Types of Paints and When to use them: Opaque, Semi-Transparent, Transparent

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There are three categories for a paint's opacity: opaque, semi-transparent, and transparent.

One is not better than another, they just have different functions. For example, in my crude illustration, you can see the difference between layers of transparent paint on the left and opaque paint on the right.

On the left, transparent layers were glazed, or painted, one on top of the other (how to create a glaze will be covered in another post). When light passes through the transparent layers, it passes through all of the layers, bounces off of the white ground, or opaque underpainting, and then back to our eye. The eye then processes all of the colors as one, and sees a red-orange. This red-orange has a depth that cannot be achieved by mixing the same color on your palette.

On the right, opaque layers are painted on top of one another. While some of the layers may be painted thinly to show colors beneath, the eye processes the colors as individuals. Instead of seeing a red-orange, we see red and yellow paint.

Opaque paints can be thinned with additional oil; however, in order to achieve true glazing/transparent results it is always better to stick with a transparent or semi-transparent paint.

It is important to know when, or rather where, to use opaque paint verses transparent paint. For bright, highlighted passages that you would like to advance towards the viewer, use opaque paint. For dark, or shadowed passages that you would like to recede from the viewer, use transparent. That is it, that is the big secret. Glazing is an exception to this rule, but that will be discussed in a later post.

Let's look at two examples.

This is the photograph "Pomegranate" by Ori Gersht. It is a homage to the Spanish baroque painter Juan Cotan. The pomegranate is exploding because a bullet just shot through it. If you look closely you can see the speeding bullet to the right of the photograph. If it was painted you would paint the lighted areas in opaque paint, the slightly darker areas of the fruit in a combination of opaque and semi-transparent paint, and finally the background painted in transparent paint.

On the right is one of my own paintings called Limao. It is also a study of Cotan. Again, you can see that the lighter, highlighted areas are more opaque, the shadows on the fruit are a combination of both opaque and transparent paint, and finally the background was completely done in transparent paint.



Below is a video that explains the above concepts:

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