Himalayan Rhubarb Extract

Himalayan Rhubarb Extract, derived from Rheum emodi (also known as Rheum australe), is an exquisite natural dye that produces unique color profiles, particularly favored for organic textile applications. Known for its rich golden-yellow hue and the capacity for pH-induced color shifts, Himalayan Rhubarb Extract is popular in textile dyeing processes that seek vibrant yet sustainable solutions. As an experienced supplier of natural dyes, Alfa Chemistry provides a high-quality Himalayan Rhubarb Extract that meets the dyeing needs of both small and large-scale applications.

Botanical Background of Himalayan Rhubarb

The Himalayan Rhubarb plant is indigenous to the mountainous terrains of Nepal, Bhutan, and northern India, thriving at altitudes between 10,500 and 17,000 feet. Rheum emodi roots are rich in anthraquinones and tannins, making them highly effective for dye applications. The primary coloring agent, emodin, interacts with other naturally occurring anthraquinones, flavonols, and sterols to produce deep, lustrous hues. These chemical constituents not only generate a vibrant palette but also provide the dye with durability and compatibility with diverse fiber types.

In Himalayan culture, this plant has held significant value for its medicinal applications; however, its primary appeal in the textile industry is due to its vibrant color profile, lightfastness, and versatility.

Chemical Composition and Dyeing Properties

Himalayan Rhubarb's root extract contains potent anthraquinones, including emodin, which serves as the principal dye component. Emodin's unique chemical properties allow it to yield a vibrant yellow that can be intensified or modified with pH adjustments. When used with alum as a mordant, Himalayan Rhubarb produces a rich golden-yellow, whereas the addition of alkaline modifiers, such as soda ash, shifts the color towards brick red. This extract is highly tannic, making it effective on both natural and synthetic fibers, even without mordants, though mordanting enhances color saturation and washfastness.

Mordanting for Colorfastness and Intensity

While Himalayan Rhubarb can dye fibers without a mordant, the use of alum enhances color depth, producing warm golden hues. For textile applications demanding durability and brilliance, fibers should be mordanted with alum before dyeing. For best results, soak fibers in water prior to mordanting to ensure even penetration. Once mordanted, the Himalayan Rhubarb Extract requires approximately 5% weight-of-fabric (WOF) to achieve robust, lightfast colors on most natural fibers.

Adjusting Concentration for Desired Shades

For wool or fibers highly receptive to Himalayan Rhubarb, a concentration as low as 3% WOF is recommended to achieve lighter, subtler shades of yellow. For deeper shades, concentrations can be increased up to 10%, accommodating the specific color depth needs of various textile applications.

pH Adjustment Techniques

Due to its sensitivity to pH, Himalayan Rhubarb allows for tailored color modifications:

• Neutral pH: Yields a warm, vibrant gold.
• Acidic Conditions (using cream of tartar or lemon juice): Shifts the color to a brighter yellow.
• Alkaline Modifiers (using soda ash): Transforms the dye to a rich brick red.

For best outcomes, Alfa Chemistry recommends conducting an alkaline afterwash rather than adding alkaline substances directly during the dye bath. This approach prevents color dilution and preserves the vibrancy of Himalayan Rhubarb's hues.

Diverse Color Outcomes with Metal Mordants

Applying different mordants allows for additional shades:

• Copper Mordant: On wool, produces an earthy brown, while on cotton, it achieves a reddish-brown. An alkaline dip using soda ash can shift this copper-based shade towards a deep brick red or maroon, offering diverse tones for design versatility.
• Iron Mordant: Notably darkens the dye to muted, olive tones, adding to the spectrum of achievable colors with Himalayan Rhubarb Extract.

It is important to note that our products are for research use only and are not for clinical use.