Cochineal bugs that feed almost solely on prickly pear cactus have been the most historically important insect dye.  They are grown, harvested and dried.   Cochineal produces very wash and lightfast reds, pinks and even lavenders. Cochineal can be dyed on wool as an acid dye, with the use of tannin and acid instead of a mordant, as has been done historically, but is most often dyed with a mordant such as Alum.   Both work well and are lightfast.  A mordant is needed to dye cellulose fibers with cochineal.

Cochineal works best with silk or wool but cotton can also be used. 25 grams of cochineal will dye a pound (450 grams) of wool a good red, and another pound or two pink.

Cochineal is very pH sensitive. The presence of acid will shift the color towards red, while an alkaline pH will move the color toward purple. I have read that it is best to use soft water with cochineal.

A true scarlet can be achieved by using tin as a pre-mordant or by adding a small amount of tin (3%) and cream of tartar (6%) to the dye bath. 

The color can be shifted toward purple with ammonia or soda ash as a post-dye alkaline pH adjuster, but a more stable purple color results from using a very small amount of iron (less than 1%) as a post-dye bath.

Over-dyeing Cochineal with Woad produces beautiful purples and over-dyeing cochineal with madder produces a true red.

Cochineal is not sensitive to boiling, so you don’t need to worry about water temperature when dyeing.  Make sure to wash your yarn in a neutral detergent after dyeing, so that you do not inadvertently change the color because of pH changes from detergent.  Original blue Dawn is said to be pH neutral.

It is often recommended to soak whole cochineal overnight before dyeing or simmer and strain before dyeing fibers.  I often like to put my fibers right in the pot with the dye stuffs.  The drawback to this with cochineal is that you will end up with dark pink or red spots on your fibers or cloth where the cochineal has laid on the fiber.

Cochineal contain a LOT of dye, so you will get a lot of color out of a small quantity, so have fun playing with the colors that it gives and have plenty of fiber ready to play with! 

If you have received cochineal extract, use .25% WOF weight of fiber for light pinks, .5-1.5% for medium pinks and 3-4% for darker pink/red.