Acid Dyes

• Color: Green, Blue, Red, Orange
• Material Type: Silk, Wool
• Brand: Rung International
• Molecular Weight : 59.07

Acid Dyes find application for dyeing protein fibers with the main protein fibers where these dyes are used for including :

• Wool
• Angora
• Cashmere
• Silk

Other than these, some other areas where these are used in include milk protein fibers like:

• Silk Latte
• Soya Protein

Acid dyes have a complex chemistry and usually have sulfur or carboxy group on a molecule that makes them soluble in water. With water being a medium where dyeing process takes place, Acid dyes are generally divided into three classes as per the:

• Fastness requirements
• Level dyeing properties
• Economy

These classes overlap and generally depend on :

• Type of fiber to be colored
• Process used

Characteristics of Acid Dyes :

• Acid dye is soluble in water and has affinity for amphoteric fibers
• It lacks direct dyes' affinity for cellulose fibers
• Dyes are non-caustic acids
• In some cases, these are also non-toxic dyes

Categories of Acid Dyes :
Equalizing/Leveling Acid Dyes:
These acid dyes help in producing similar, single color solid effects and have highest level dyeing properties. Combined in trichromatic shades, the items dyed with leveling acid dyes should not be machine dyed or washed in warm water. Instead, the washing needs to be done in cool water through dry-cleaned/hand washed process.

Milling Acid Dyes :
Mainly used for self-shading, wet fastness of these dyes is available in medium to high range. With some of these Milling Acid Dyes having bad light fastness in pale shades, these dyes are not generally combined with other dyes.

Super Milling Acid Dyes :
These have:

• Higher neutral dyeing affinity
• Better coverage of dye uptake differences in substrate

Some of the areas where these are used in include Milk protein fibers like:

• Silk Latte
• Soya Protein

• Physical State: Liquid
• Grade Standard: Bio-Tech Grade, Reagent Grade
• Usage: Ink Dyestuffs, Paint Dyestuff
• Brand: Rung International

There has also been an increasing usage of dyes in the medical sector. Here, dyes act as an important ingredient in many of the medical tests conducted on humans.

These dyes in coordination with latest diagnosis equipment allow flawless handling and high accuracy in tests that are carried out on patients. One such dye example is Fluorescein angiography that derives its name from fluorescein. This dye is successfully used for carrying out tests like Angiogram which provides valuable information about the circulatory system.

The process of using dye in Fluorescein Angiography Test:

• A special dye called fluorescein is injected into vein in arm
• Within seconds, dye reaches blood vessels inside eye
• Camera with special filters highlights the and is used for photographing fluorescein as it keeps on circulating through blood vessels in back of eye

This dye has the ability to detect abnormalities like:

• Circulation problems
• Swelling
• Leaking or abnormal blood vessels

All these abnormalities can be seen in the photographs. Based on the arrived results, doctors then decide on the diagnosis and possible treatment options. Almost all dyes that find usage in the medical sector are synthetic in nature with only a few varieties that fall under natural dyes. These dyes are used for applications like:

• Color tablets (coated/uncoated)
• Staining on shell capsules
• Syrup coloring
• Providing color to drug that enhances the aesthetics as well as aids product identification

Use of Dyes in Different Medicines:

Tablets:
Tablets colors are made using tablet coating technology. The coating film on tablets aims to:

• Enhance the aesthetic of tablets
• Help in maintaining product identification

There are two types of dyes that are used in film coatings:
Synthetic Dyes:
These dyes are approved by FDA (Food and Drug Administration) an organization that approves relevant dyes in foods, drugs and cosmetics sector.

Natural Dyes:
Here, chlorophyll, anthocyanin, and carotenoid are used at the time prior to printing color tablets, mixing both dry and wet granulation.

Capsules:
Dyes are particularly used in the hard-shelled capsule. These may be from a variety of iron oxide, opaque material like:

• Titanium dioxide
• Dispersing materials
• Hardening materials like sucrose
• Preservatives

Further, soft capsules can also contain pigments/dyes in form of, opaque materials like:

• Titanium dioxide
• Preservatives
• Fragrances
• Sweeteners

Syrups:
Dyes are also used in syrups where it helps in providing attractive appearance as well as distinguish the preparation from others available in the market. Some of the commonly used dye in syrups includes:

• FD & C dyes
• D & C Dye

These dyes are added to syrups and adjusted to the essence, for example:

• Medicinal syrup with orange flavor (add yellow/orange dye)
• Medicinal syrup with mint flavor (add white dye)
• Labels: Colorant, Coloring Agent, Dyes