It might seem sacrilege talking about mixing watercolor painting accessories such as mediums and additives with watercolour paints.
It is, after all the purest of paint types, relying on its translucency to allow the whiteness of the watercolour paper to glow through.
However, there are several traditional mediums and additives which can make life easier for the watercolorist and add a new dimension to their painting.
Technological developments have also promoted some quite new mediums and undoubtedly, the rise in popularity of watercolor painting has had something to do with this as well!
Here's a brief description of the main watercolor mediums and how to best use them...
Oh, and you'll notice I freely mix the term 'watercolor mediums' and 'additives'. For the purpose of this article they mean the same thing.
Don't get confused by the term 'painting medium' which can also mean the type of paint you use, e.g. oils, acrylics, pastels and so on.
Right, now for a description of each watercolor medium - er, or additive...
Art Masking Fluid. In one sense, not really a watercolor medium since you don't mix it with or add it to your paints. But a popular technique nevertheless. A latex rubber solution for brushing or drawing onto your paper. Once it dries thoroughly, in a few minutes, you can paint over the masked area, which being latex, resists the paint. You can get the same effect with a plain thin piece of wax candle, but this is permanent and you can't subsequently paint over the reserved area.
After the paint has dried, remove the masking fluid gently with a clean finger, a putty rubber or cotton bud. It'll roll up into little rubber balls. The white area can be left as a highlight or tinted as desired.
Various ways to apply the fluid are brush, color-shaper (a sort of paint brush with a pointed rubber tip instead of bristles), drafting bow-pen, cocktail stick, edge of a credit card, cotton bud, etc. If you intend using one of your watercolour brushes, or any other brush for that matter, make sure it's an old one and wash it out immediately.
Masking fluid starts drying quickly (and I mean in less than one minute) on the bristles of a brush. Never risk using a half decent brush with masking fluid. You will ruin it!
It is ideal for reserving intricate shapes (window and door frames, middle distance animals, ships masts, tree trunks, thin grasses, etc.) so that painting straight across the masked area permits confident, decisive brush strokes. This is one of the most popular watercolor mediums. However, use it with discretion!
Most watercolors contain a proportion of gum Arabic. A soluble gum (remember the old bottles of light brown office gum?) which when used on its own increases the gloss and transparency of a watercolor. Slows down the drying time of paint.
Ox Gall Liquid
Increases the wetting properties and flow of watercolors with a few drops to your water pot. Useful for 'marbling' techniques on hot pressed paper.
Granulation Paint Medium
Encourages watercolors to granulate i.e. take on a mottled texture on the paper surface when dry.
Lifting Paint Medium
Applied to the paper and allowed to dry before applying paint, this enables you to lift off colors for highlights etc. more easily.
Slows the drying time of colors. Ideal in very warm climates and can be used undiluted with watercolors for maximum drying time. You can get the same effect by adding a little alcohol to your water.
This also works in very cold outdoor situations, where mixing plain water with watercolor paint can actually freeze it on the paper. I think gin is one of the best watercolor mediums because it stops me freezing as well...
Add to transparent colors to give pearl or glitter effect.
Texture Paint Medium
Add to paper or mix with colors for textured effects.
Watercolor Impasto Gel
The concept of3D watercolor takes some getting used to! Can be mixed 50/50 with watercolors and applied to paper with knife or bristle brush, especially in foreground areas.
So there we are. A brief overview of pwatercolor mediums. There are always more paint mediums becoming available, but the list above should keep you occupied for a while.