Transparent vs Opaque Colours in Oils and Acrylics

A misunderstanding I regularly encounter in workshops is what is meant by “transparent” in a paint colour. It seems to come from conflating “see-through” and “colourless” into “transparent”.

We can see through some things that have colour. Think of stained glass or coloured cellophane or sunglasses. You see through it, though it adds colour to what’s behind it, changes the colours of things seen through it. Normal window glass is colourless; stained glass is transparent (to varying degrees, but that’s a digression).

If you’ve done a workshop with me, you’ve probably seen this “visual aid”. One day I’ll create a neater, textbook version!

At the bottom right of that sheet is a black line with opaque, semi-opaque, and transparent colours painted over it.

Pigments Transparent vs Opaque

How opaque or transparent a pigment is depends on the inherent properties of a pigment, but also how thickly you use it. Red iron oxide is one of the most opaque pigments there is, even more than titanium white. It obliterates whatever’s beneath it.

Figuring out which colours are which is best done by creating a chart of your own. Yes, many tube labels give an indication, but you can’t beat trying it for yourself, straight from the tube and thinned somewhat, as well as adding white to transparent pigments to shift their opacity.

It’s an excuse to get out every tube of paint you’ve got and say hello to it. Neatly in a grid or not, that’s a potential procrastination. Just put brush into paint onto paper and save neatly for another day.

Also: Transparent Watercolour Doesn’t Mean Colourless Paint

2 Replies to “Transparent vs Opaque Colours in Oils and Acrylics”

  1. What if an artist used only
    transparent/translucent types
    of paint in a couple of their paintings. I know that they are
    not too many of them out there.
    But I would like to know if it is
    worth the effort. I believe that
    it would leave them in a very
    limited range of styles to paint
    from. Thank you so much.

    1. I think it is well worth exploring the transparent pigments as they give such beautiful results. Colour mixing by layering (glazing) can make colours really glow.

      It limits the way you apply colour rather than style because you work from light to dark, you can’t lighten a part of a painting because lower layers of paint always show through.

      I think ultimately though there’s no reason beyond a personal challenge to work with transparent colours only.

      The next step after this is to explore making opaque colours semi-opaque with a glazing medium, and then the impact of using small areas of strongly opaque colour. Scottish artist Joan Eardley was a master of the latter in her landscapes.

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