Mordanting fibre for cochineal dyeing
You need to mordant your fibres with alum before cochineal dyeing and you can obtain several different types of red with cochineal, using different mordants. To produce scarlet you can add a small amount of tin to the wool at the end of the dyeing process. Cream of tartar alters the colour towards crimson. A small amount of lemon juice shifts the colour towards orange. You can find much more information on mordants and mordanting on the Wild Colours Natural Dyes website
Water quality in cochineal dyeing
It is important to use soft water when dyeing with cochineal. If you live in a hard water area, collect rain water or use distilled water. Hard water gives very pale colours with cochineal, apparently due to the dye bonding to impurities of the water rather than bonding to the fibres.
Grinding cochineal for dyeing
Most books suggest grinding the cochineal using either a pestle and mortar or an electric coffee grinder reserved just for dyes. Be careful when using a coffee grinder as the fine powder gets everywhere. A small brush or a large, stiff feather may be useful in removing the powder from the coffee grinder.
This instruction prevented me from using cochineal for a long time, however, as I had neither a spare pestle and mortar nor a coffee grinder. Eventually, I discovered an easier and less messy method. Put some cochineal in a strong polythene bag, close the bag well with adhesive tape and gently roll a rolling pin over the bag until all the cochineal is ground (don’t use a grip seal bag, which would burst).
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