DIFFERENCE BETWEEN WATERCOLORS, GOUACHE & POSTER COLORS

Before starting out on the differences between Watercolors, Gouache & Poster Colors, let me point out one similarity between them, which is that all three are actually water-based. This simply means you can activate the paint both in paper & palette with water. The differences however come from many factors which we will be discussing pointwise below:

Pigments:

One of the most important difference between watercolors, gouache & poster colors is its pigment content.

Generally speaking, to make these colors three things are used: a pigment, a binder & some additive.

The pigments used in watercolors are very small & therefore it easily mixes giving us a light & transparent layer. Subsequent layers in a watercolor layer will result in more depth in the painting.

The pigments used in gouache are bigger than the ones used in watercolors. These give us a semi-transparent or semi-opaque result as the paint sits on the surface of the paper rather than staining it like watercolors.

The pigments used in poster colors are comparatively larger in size & therefore creates a very opaque result.

And generally speaking, the pigments, binders & additives used in Watercolors & Gouache are superior in quality which makes it more expensive than poster colors.

Opacity:

The previous point already discusses the opacity of these three colors. Watercolors are very transparent when applied on a piece of paper. If you want an opaque result in a watercolor painting, less water mix & more layers are needed to achieve it.

PS: You will need to leave paper-white to achieve highlights as you will not get total whites once the paper is stained with watercolor wash.

Gouache is semi-transparent or semi-opaque, however you like to call it. It sits on the surface of the paper & is not transparent when compared with watercolors.

Poster color on the other had creates an almost opaque effect when applied on a surface. If you want highlights, you can paint over it with the desired color once its dry.

Painting technique:

Watercolor-Light to dark

Gouache-Light to dark & dark to light

Poster Color-Only dark to light

Surface:

For best results, Watercolors may only be used on a proper watercolor paper. But Gouache & Poster colors can be used on other thicker & colored papers too since these two are not transparent in nature & therefore the original paper surface is covered with its pigment.

Pricing:

While this is not an exact parameter to differentiate between Watercolors, Gouache & Poster colors, but it’s worth mentioning that poster colors are much cheaper than the other two.

However, there is still a sizeable price gap between Student grade & Artist grade watercolors or Gouache. That mainly depends on the type of pigment & binder used. Needless to say, Artist grade colors are made using natural pigments to give a stronger & superior quality output.

Student grade colors use less & synthetic pigments and hence are much cheaper.

Uses:

Watercolors are used to create fresh-looking & unexpected washes in a painting. I have seen people hooked solely to Watercolors just for these reasons.

Gouache is used when you want to achieve oil like results but want the medium to be water-based. Or let’s put it this way: Gouache is used when you want to paint from dark to light rather than light to dark as we do in Watercolors. The paintings or illustrations done using gouache & poster colors are bold (but most of the time flat), which is good for reproduction through scanning.

Light fastness:

Light fastness is by definition is the how much resistance the paint carries against fading when exposed to light in the long run.

As I mentioned before, Poster colors are good for reproduction & not for display. They are very lightfast (meaning they won’t fade away when exposed to light for a long period of time).

But Watercolors are less lightfast or easily fade away with time when exposed to light. This I am saying in comparison to the other two colors.

To summarize it, we can simply rank the three in the increasing order of their lightfastness as Poster colors, then Gouache & Watercolor in the end(which is the least light fast of the three).

Packaging/storing:

Watercolors come in most of the forms possible commercially. They range from tubes to pans to sticks to bottles(liquid form).

Gouache comes only in tubes, while poster colors are usually sold in small bottles & sometimes in tubes too.

Result when dry:

In Gouache, dark colors when dried tend to appear lighter & light colors tend to appear darker when dried.

Watercolors when dried creates a lighter result. Therefore, more than one layer is always desirable to create that effect of depth in a watercolor painting.

I hope these comparisons helped you to understand the basic differences between Watercolors, Gouache & Poster Colors.

Personally, I love transparent watercolors.

Which one do you like or use?