Extracted from plants and invertebrates (e.g., insects and mollusks), natural dyes have been used to dye textiles for over 5,000 years whereas synthetics first appeared in the mid-19th century. Environmental benefits aside, natural dyes contain multiple compounds that create depth and intricacies not otherwise possible with synthetic dyes. Madder (rubia cordifolia), for example, contains munjistin as its principal dye as well as purpurin and pseudopururin, all of which together give a richness to the dyed goods.

Though many objects in nature contain brilliant colors, not all can be used for dyeing. Textiles require “fast” natural dyes, which simply means that the dye will not quickly wash out or fade in ultraviolet light. “Fast” natural dyes form a stable bond with the textile and come in three varieties: (i) vat dyes, (ii) mordant dyes, and (iii) direct dyes. “Fugitive” dyes, however, lack the chemical affinity for natural fibers and mordanted textiles. They will merely stain fabric and quickly wash out. Most berries are considered “fugitive” dyes despite their saturated coloring.

VAT DYES - Vat dyes (e.g., indigo and murex mollusks) are insoluble in water. To bind the dye to the fibers, the dye must first be “reduced” to become soluble. Once reduced, the dye can penetrate and attach to the fiber in the vat. When the fibers are removed and allowed to oxidize, the dye becomes insoluble in the fibers.

MORDANT DYES - The bulk of natural dyes are mordant dyes. The most common mordants for natural dyes are derived from metallic salts such as alum, aluminum acetate, and ferrous sulfate (iron). Mordants allow the dye to bind to natural fibers, creating colors that are lightfast and washfast.

DIRECT DYES - Also known as substantive dyes, direct dyes (e.g., cochineal, cutch, and henna) have an affinity only for protein fibers and do not require a mordant to attach.

Natural dyes work best with natural fibers, which are classified into two categories: cellulose and protein. Cellulose fibers are derived from plants whereas protein fibers are animal based. Though natural dyes work effectively with both categories, protein fibers are much easier to dye and saturate. Cellulose fibers simply take more time and preparation to achieve the desired result. There’s a science to it, but that’ll have you daydreaming.

Synthetic fibers (e.g., acetate, elastane, polyester, and nylon) are not receptive to natural dyes. They may ever so slightly stain but usually remain the same color as before being dyed. If you were to grab a generic white cotton tee and dip it into an indigo vat, you’ll likely obtain a blue t-shirt that will have contrasting white topstitching as it was likely sewn with white polyester threads.

CELLULOSE FIBERS - The principal, non-regenerated cellulosic fibers used for apparel textiles are cotton, linen, hemp, and ramie. Regenerated cellulosic fibers include rayon and lyocell and are derived from wood pulp. Often, a regenerated fiber will be listed by its registered trademarked name, such as Tencel, Lenzing Modal, and Lenzing Viscose.

PROTEIN FIBERS - The most prolific protein fibers for apparel textiles are silk and wool. Other hair fibers commonly used include alpaca, camel, cashmere, and mohair.

SCOURING – Natural fibers may contain impurities from their natural state or accumulated during processes that turn fibers into yarns and subsequently into knitted or woven fabrics. The process of scouring ensures that any dirt, oil, sizing, and waxes are removed from the fibers to allow them to evenly absorb mordants and dyes. Scouring is simply the process of washing the textiles with a pH neutral detergent. The water after scouring may appear slightly murky or as dark as black tea, depending on the level of impurities in the fibers.

MORDANTING – Mordanting ensures that the dyes will bind and become stable in the fibers. While not necessary for direct dyes on protein fibers, the process of mordanting textiles involves immersing them in a solution of water and a given mordant (e.g., alum, aluminum acetate, copper, iron, and tin). The desired outcome and whether the fibers are protein or cellulosic determine which mordant is appropriate. Protein fibers are primarily mordanted with alum. Cellulose fibers, however, require an additional step prior to applying a mordant, as mordants themselves have no affinity for cellulose. So cellulosic fibers are first placed in a tannin bath, which has an affinity for cellulose, and then placed into a mordant bath in which the mordant and tannin become bound and insoluble in the fibers.

DYEING – Creating a dye bath involves either extracting the natural dye or using a natural dye extract. The extraction process typically involves simmering the raw dye material (e.g., madder root, dried marigold petals, dried cochineal insects) in water for an hour or two. Multiple extractions may be performed to increase the amount of dye. Extracts simply need to be dissolved in water. The textiles are then immersed into the bath and heated to the appropriate temperature. Depending on the dye and depth of color, the textiles will remain in the bath for at least thirty minutes and up to two hours. Once done, and if no other effects are desired, the textiles can be rinsed and washed with a neutral detergent.

Dyeing natural fibers with indigo is markedly different from nearly all other natural dyes. Indigo is not soluble in water, which means that neither mordanting nor extracting the dye in water are necessary. The fibers must still be scoured, but the principal difference is the process by which indigo becomes soluble and able to bind to the fibers. This involves a chemical process called “reduction,” which essentially means to remove oxygen. We’ll skip over the science behind it and merely describe the process.

Natural dyers reduce indigo in one of two ways: (i) with sugars, fruits, or plants or (ii) with minerals such as iron or zinc. In addition to the reduction material, both methods require water, indigo and calcium hydroxide (calx) to maintain the high alkalinity required for reduction. The mineral vat requires a higher alkalinity that is not suitable for protein fibers. Once all ingredients are mixed in their proper proportions, the vat will reduce within a day or two. In the reduced state, the liquid in the vat will have a clear coppery color.

Textiles are immersed into the vat for anywhere between a few to twenty minutes. After removing the textile from the first dip, it will initially appear yellow/green and gradually turn blue upon oxidation. Typically, the textile will be allowed to oxidize for at least thirty minutes. Textiles may be dipped multiple times to obtain gradual, darker shades of blue.

Various methods exist to achieve effects on clothing beyond dyeing them with only one natural dye. Compound colors are endless—indigo can be overdyed with weld for bright, grassy greens, madder and marigold can be combined for rustic oranges, and tannins can be immersed in a ferrous sulfate (iron) afterbath for varying shades of gray. While yarn-dyed fabrics necessary for plaids and stripes are not practical (i.e., very expensive) in the world of natural dyes, such effects can still be achieved by curating fabrics intentionally woven into those patterns with a mix of undyed cellulose and protein yarns. A combination of indigo dyeing, one-bath acid dyes, and cross-dyeing can bring those patterns to life, and we strive to source those fabrics and use those methods when practical.

Though the natural dye process does not release toxic chemicals into the environment, it is nonetheless resource intensive between farming the raw materials and logistics. When possible, we like to reuse and conserve throughout the natural dye process. Tannin and mordant baths can be recharged after their first use. Dyebaths can be used multiple times for exhaust dyeing. With each successive item, the shade will lighten but plenty of color attaches to the fibers, and we enjoy offering those shades as limited runs and using them for our experimental (Found) Objects collection.

Even after all that, pigment can still be separated from the dyebath in the form of a lake pigment and used to create watercolors and inks. We create these paints at our studio to be used on our hangtags or simply to slow down and paint whatever comes to mind.