Build a solid foundation in science, formulation and product development—find out more!
Most Popular in:
Dyeing to be Natural
By: Katie Schaefer, Cosmetics & Toiletries magazine
Posted: June 30, 2009, from the July 2009 issue of Cosmetics & Toiletries.
page 2 of 3
Henna, a commonly used natural dye, did not exhibit the efficacy he was after. “The dyes we selected have a performance advantage over henna. With henna, you can only get some reds and oranges. Also, the pigment coats the hair, so if the consumer decides they do not like it, it is hard to remove or color over it,” said Greaves.
The main objective for Greaves was to achieve natural permanent hair colors that are stable, strong and that stick. In many cases, Greaves bred plants specifically to create strong plant dyes. “We have plants such as madder [an herbal extract] that are selectively bred for their pigments. Madder contains multiple pigments in various forms but we only wanted certain ones-and we wanted to breed down the solids and sugars that we would have to pull out. There is a lot of trial and error to get the pigment you want,” conceded Greaves. This trial and error can involve plant exchange resins and solvent extraction. “We are not separating the molecules,” explained Greaves. “We are just isolating them.”
Most of the edible pigments chosen by Greaves are from vegetables. For example, he formulates with indigo from Indigofera tinctoria, a violet pigment from red cabbage, and anthocyanins from purple sweet potato, red radish and purple carrots. “Some of the traditional anthocyanin sources such as grape are less stable,” said Greaves, who added that they also contain an overabundance of tannins and sulfur dioxides. Instead, he searched for dyes containing double bonds to make them resistant to oxidation.
Reaction for Deposition
To deposit the dye into the hair, Greaves’ color kit reacts the plant-based dyes with mineral salts and the protein in hair to form a stable complex. The mineral salt is a divalent or trivalent ion that creates a bond with the protein. The dye does not open the cuticle like traditional dyes.
“Typically the isometric point of hair is around 4.5. An oxidative dye molecule is too large to get into hair. Therefore, the formulator would have to use an amine to raise the pH of hair to get the molecule [to penetrate]. This is typically done with an alkaline substance such as ammonia to open the cuticle,” said Greaves.