Watercolor and Gouache
Preparing the binder
Making the gum solution
Both Watercolor and Gouache use the same binder. The gum solution does not keep well so make it up in small quantities each time you grind paint. Adding a preservative such as phenol (a few drops at 10%) is recommended. This is how it is prepared.
  • 2 parts of pulverized Gum Arabic
  • 4 parts of boiling distilled water
  • 1 part of Glycerin
  • 2 drops of wetting agent per 100 ml
  • 2 drops of preservative per 100 ml
Glycerin is a plasticizer that can easily be obtained at a pharmacy. Put the Gum in a pot and pour the boiling distilled water over it. (All utensils used have to be scrupulously clean otherwise the paint will not last.) Stir in the glycerin. After cooling strain the solution through cheesecloth into a clean glass jar. Some recipes call for additions of Honey water or sugar syrup  and this can be added in an equal quantity as the glycerin. Keep good records and let your painting experience guide you in exact ingredients that suit you. The addition of Dextrin is to be avoided. A wetting agent can be avoided by adding a few drops of grain alcohol to the dry pigment, or by predispersing the pigment to a paste.

Grinding on the slab Also called dispersal
The grinding of Watercolor and Gouache are somewhat different so I will treat them separately. Gouache is one of the easiest paints to make, but Watercolor is one of the most difficult and should not be attempted unless having a high level of motivation. Watercolors easily give problems such as being too grainy or lifting from the paper too easily. Fine tuning ingredients and following accurate paint making records is essential. 

On the slab mix a small amount of binder into the predispersed pigment. (No more than a quarter by volume to start, although some pigments may require up to a third). Grind the paste thoroughly with the muller. Use a watercolor brush and paper to make a wash from the developing paint to test how the grind is going. Watercolor needs a lot of grinding. The water will evaporate and the paint becomes difficult to grind, do not add binder at this point but instead add distilled water only. A good way to do this is via a plastic spray bottle as this wets the paint all over without over wetting. Grind in a circular motion that spreads the paint thinly and periodically scrape the edge of the muller and scrape the paint into the center to continue grinding. Judge the finish of the grind by the quality of a wash on good watercolor paper. Testing how easily the wash lifts indicates if enough gum solution is present and a shiny surface to the wash indicates too much gum it will vary from pigment to pigment. Getting Watercolors just right is an artform in itself, although the rewards can be great. If the paint is a little too wet it can be left to evaporate a little on the slab.

Gouache is very easy to grind. Gouache is even more susceptible to attack by microorganisms than Watercolor and needs a little extra preservative in the gum solution. Predispersing the pigment with an equal portion of precipitated chalk make grinding easier but is not essential. If grinding the dry pigment and chalk directly use a little Grain Alcohol to help with wetting. The paint can be quite wet while grinding and allowed to dry a little on the slab. Add gum solution at a rate of one third gum to the pigment and chalk. Painting a little out on watercolor paper during grinding gives a good indication of adjustments that might be necessary in terms of additional gum and grinding. The paint needs to be smooth, reasonably liquid, and opaque.

[ Go to  Testing Paints  ]

Tubes and jars and pans Storing paint usefully
If desiring to make pan type Watercolors use a minimum of water and gum solution. If storing in tubes use a little more water, preservative, and gum. Empty pans can be purchased although I favor tiny wide mouthed glass jars that are little bigger than pans but have the advantage of a plastic screw lid. Of course pans do fit into standard tin watercolor boxes made for pans and half pans.

It is convenient to simply store and use Gouache in small glass jars with plastic lids. For those who love tubes there is no reason the paint cannot be loaded into tubes although glass jars make it easy to see colors at a glance. As with all paint it is wise to note paint making date on each container with a permanent marker.

Related Links:

Studio notes

Basic Ingredients

Detailed Ingredients

Testing paint

Starting to make paint

Making Oil Paints

Making Acrylic Paints

Making Egg Tempera

Making Hide Glue Chalk Gesso

Making Encaustic Paint

Making Fresco Colors

Making Pastels

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