These pigments can be brought from shops and they all have slightly different characteristics - some dry faster than others, or need more water/gum Arabic. They typically last for a long time and will go a long way for very small amount.
Even if they have dried up, you could revive the colours by adding water and gum Arabic to it again, preferably with your finger to grind down the little lumps. Make sure you let them dry naturally and not let them go mouldy ( e.g. indigo as it is an organic plant)
Step 1 - Add the pigments in the centre of a glass sheet ( can get it cheaper as a piece of sand blasted glass, use the grainy side)
Step 2 - Make it a paste ( we are using zinc white) add water, and gum Arabic 10 to 11 drops for the pile as shown. better to add more later so don't add too many drops. (Not enough gum Arabic the paint could be rubbed off easily, too much and the paint will crack.) Mix all well into a paste.
Step 3 - Use a glass muller to grind the paste to get rid of the lumps until the paint is even and smooth. Bring the paint back to the centre and scrap into a bowl when this is done.
Step 5 - this is a must, after mixing the paint it is a good idea to paint it on a paper strip, let it dry and then rub fingers against the paint. If it rubs off the paint will need a bit more gum Arabic - at this point just add a few drops in the bowl and mix with the brush and retry - only a few drops at the time and don't overdo it.
Step 6 - We have mixed a yellow that everyone is happy with and we trace the outline of the image first and fill in the paint, trying to paint once and not retracing the paint area too much.
Step 7 - To make it more interesting our teacher suggested that we add a line of green paint at the top and then wash it with water for variation. We have done quite a lot in the class this time!
TIP - home made Gum Arabic - add cold water for one hour and strain with Muslim cloth
