Making soda ash

Soda ash, also known as washing soda can be purchased, but can also be made by cooking baking soda for 1 hour at 200F. Cover with foil to prevent powder from poofing inside your oven and making a mess. Once cooled, store in a sealed and labeled container.

How much soda ash and alum?

The intensity of a plant’s pigment determines how much of each you need. This is a work in progress and I’ve been using the guidelines provided by Natalie Stopka, guessing and experimenting for my plants not listed. Generally, if something is a lower intensity pigment it will need less alum, but very highly pigmented materials need much more. Soda ash is about half of the alum used, although sometimes I’ve needed a little bit more. Plant quality, seasonality, and other factors may affect these results. It’s all experimental.

fresh/frozen material (dried about 4x more concentrated)	weight of alum relative to weight of plant material
Goldenrod (fresh flowers)	18%
Avocado pits	25%
Firebush berries (fresh/frozen)	25%
Marigold (fresh petals)	30%
Roselle (fresh/frozen, de-seeded)	65%
Prickly pear fruit (fresh/frozen), Calendula, coreopsis, cosmos (dried)	70%
Poke (fresh/frozen berries)	90%
Cochineal insects (dried)	90%

Example: 10g fresh prickly pear fruit

10g x 70% = 7g alum and 3.5g soda ash (1/2 of 7g)

Example: 10g dried marigold petals

10g x 4 = 40g x 30% = 12g alum and 6g soda ash (1/2 of 12g)

Making Watercolor Medium

To make your beautiful dried pigment into paint, it is mulled it with a watercolor medium solution. The solution contains a binder (tree gum) that holds pigment particles together, a humectant (honey and/or glycerin) that allows paint to be re-wetted, water, and a preservative oil. Gum arabic from the acacia tree is mostly commonly used and available commercially. Liquid gum arabic can be used as is. In powdered form it is dissolved in water over low heat – about 60 g powder and 140ml of water. Other foraged tree saps can be used as well, just not from coniferous trees – that’s resin/glue! I’ve recently been experimenting with the very gummy monkey ear tree (Enterolobium cyclocarpum) that grows well here and is used in permaculture landscapes.

• 140 ml liquid gum solution
• 20 ml honey (approx 1 part honey: 9 parts gum solution)
• 45 ml glycerin
• drop or two of thyme or clove oil for preservative

Shake well and store in a labelled squeezy bottle in the refrigerator. Depending on the results of your final paint, you may decide to add more gum (too flat), less honey (too sticky) or more watercolor medium proportional to pigment (too dry). Mulled pigments can be re-ground and mulled again to get them the way you like.