Fluorescent fabrics have been really popular because of their highly saturated and strikingly bright colors, but their delicate dye characteristics place higher demands on the professional care capabilities of laundries. Improper treatment easily causes color peeling, staining, or brightness attenuation and serious customer complaints. This article will systematically analyze its characteristics and provide a standard operational process.
Fluorescent Dyes for Textiles
There are three dyes: fluorescent whitening agents, disperse fluorescent dyes, and fluorescent coatings.
- Fluorescent whitening agents
Fluorescent whitening agents have been widely applied in aspects like textiles, paper-making, laundry powder, soap, rubber, plastic, pigment, and paint.
In the textile industry, the whiteness of the fibers cannot meet people’s requirements for elasticity, especially natural fibers. Because of the difference in living environments and growth cycles, their whiteness has a great difference. White substances generally absorb blue light in the 450–480 nm range of visible light slightly. This results in insufficient blue light and leaves a slight yellowish tint that gives people a stale appearance.
Fluorescent whitening agents can absorb high-energy near-ultraviolet light and cause their molecules to enter an excited state. Then the excited molecules transition to a lower-energy ground state and emit fluorescence.
Due to energy loss, the wavelength of the emitted fluorescence becomes longer (corresponding to blue light at about 450 nm). The yellowish tint of yellowed items can be compensated for by the blue light reflected by fluorescent whitening agents, thereby improving the whiteness of the items. Since the intensity of the emitted light exceeds that of the original visible light incident on the treated fabric, a whitening effect with a slight tint is achieved.
A fluorescent whitening agent to be practically useful not only absorbs ultraviolet light and emits violet-blue fluorescence, but also has high fluorescence efficiency. They are also nearly colorless or slightly yellowish themselves. Additionally, it should have the characteristics of ordinary dyes, including good affinity for the fabrics (e.g., fibers) being whitened, excellent solubility or dispersibility, and satisfactory fastness properties such as wash resistance, light resistance, and heat resistance.
- Disperse fluorescent dyes
Disperse fluorescent dyes have small molecules and no water-soluble groups in their structure. With the help of dispersants, they disperse uniformly in the dye liquor and penetrate into the fiber interior. After padding the dye liquor, the fabric is dried immediately, followed by heat-setting treatment. Under high temperatures, the dyes deposited on the fabric can diffuse into the fiber interior in the form of single molecules, completing the dyeing of chemical fibers in an extremely short time.
Since the small molecules of fluorescent dyes fuse with the fibers, the fabric has excellent rubbing fastness and washing fastness, but relatively poor light fastness.
- Fluorescent coatings
– Fluorescent coatings are pastes composed of fluorescent pigments, dispersants, and wetting agents. They are insoluble in water and have no affinity for fibers, so they are unable to dye fibers in conventional dyeing conditions.
– If the fluorescent pigment particles are large, the coloring power will be low, the shade will be dull, the fastness will be poor, and the shade will be difficult to control accurately. If the particles are small, the coloring power will be high and the fastness will be better, but the vividness will be affected.
– Fluorescent coatings adhere to the fiber surface through padding, and the resin component in the binder helps fix the coatings on the fiber surface to achieve a level of dyeing fastness. Due to the influence of the resin contained in the binder, the fabric’s hand feel will become stiff.
Characteristics of Fluorescent Coatings
Fluorescent fabrics are ordinary fabrics that have a strong reflective effect after fluorescent dyeing or coating finishing.
The use of fluorescent fabrics makes distant targets or targets in the darkness reflect intense light strongly, thereby achieving good warning and safety prevention effects.
Fluorescent fabrics are mainly made of chemical fibers, dyed with disperse fluorescent dyes, so they have good washing fastness and bright colors. Cotton, linen, silk, and wool fabrics basically use binders to make fluorescent coatings adhere to the fibers. The fabric color varies due to factors such as surface texture, coating concentration, dye uptake rate, and pH value. In some cases, fluorescence emission may not occur at all, resulting in ineffective fluorescent colors.
Usage Issues and Misconceptions of Fluorescent Fabrics
There are some disadvantages in terms of color.
- Fluorescent fabrics have poor light fastness.
- Fluorescent coatings feature poor crock fastness and severe color fading after washing.
- For cotton, linen, wool, and silk fabrics, fluorescent colors face problems such as difficult color matching, dull luster, and low fluorescent reflectivity.
Core Challenges
Why are fluorescent fabrics high-risk? Here are some reasons.
- Unstable dyes
To get vivid colors, the dyes have unstable molecular structures. They are more sensitive to mechanical force, temperature, and chemical solvents.
- Easy color migration
During the washing process, especially water washing, free dyes are highly likely to peel off from the fabric. They may stain other light-colored parts of the same garment or other clothes washed in the same batch. This causes irreversible damage.
- Sensitivity to some chemicals
Contacting with chlorinated dry-cleaning solvents (perchloroethylene or chlorine-containing bleaches) may trigger chemical reactions in the dyes. This leads to discoloration.
Pretreatment
Here are some important inspection steps.
- Check care labels
Strictly follow the care labels.
- Color fastness test
a small amount of the detergent you plan to use (or clean water) → dip a piece of white cotton cloth in it → rub gently on an inconspicuous area (the inner side of the garment) → observe if there is obvious color fading.
- Clear risk notification
Inform customers in advance that due to the physical properties of fluorescent fabrics, washing may cause slight color attenuation or brightness loss. Note this on the laundry order to manage customer expectations effectively.
Selection of Washing Solutions and Key Operational Points
The top solution is gentle water washing. According to characteristics that fluorescent fabrics are sensitive to temperature, mechanical forces, and detergents, the gentle water washing should be strictly controlled in terms of the parameters. Kingstar professional wet cleaning machines (15/20/25kg) have been the ideal machines in this scenario. The specific advantages and operational points are as follows.
- Selection of detergents
People should use neutral/pH-balanced detergents designed for bright-colored fabrics. Chlorine-containing bleaches or strong stain removers should be strictly banned.
Kingstar wet cleaning machines have an automatic detergent dosing function, which can precisely control the detergent dosage. This avoids dye damage caused by excessive manual addition while ensuring uniform washing results.
- Separate washing
Clothes should be washed separately according to different colors. Fluorescent clothes must be separated from light-colored clothes and clothes with no color.
The Kinsgtar wet cleaning machines have many capacity options (12/15/20/25 kg). This meets the needs of delicate washing for single pieces or small batches and adapts to different business requirements of the store. In addition, it avoids color contamination caused by mixed washing.
- Process Parameter Control
– Water temperature
Stably maintaining a cold water environment or a low temperature of ≤30°C by virtue of the equipment’s precise temperature control system can avoid damage to the fluorescent dye structure caused by high temperatures. This reduces color fading at the source.
– Mechanical force
Use the equipment’s exclusive washing mode of “gentle/delicate fabric”. Its minimum rotation speed of 15 rpm (revolutions per minute) and customized stop/start ratio can significantly reduce damage to fluorescent fabrics from mechanical friction. Also, it supports personalized adjustment of washing time, like shortening the main washing cycle, reducing the contact duration between dyes and water, and lowering the probability of color migration.
- Dehydration
Select the equipment’s “low-speed dehydration” function, or set a short dehydration duration via the program. This avoids fabric deformation and dye shedding caused by mechanical force generated by high-speed dehydration. After dehydration of very delicate fluorescent-coated fabrics, people can use a towel to absorb extra moisture and then lay them flat to air-dry. This ensures fabric safety.
- Damage-proof structure
The garment loading interface of the equipment has a 4–6mm narrow-gap curled edge design and a convex glass door. This effectively prevents zippers and decorative parts of fluorescent garments from getting stuck in the door gap (which would cause fabric scratches) and avoids local color fading due to dye loss from fabric damage. The inner drum (304 stainless steel), diamond-patterned mesh, and 3mm apertures not only solve rust contamination but also improve cleaning efficiency. Also, it prevents scratches on the fluorescent coating and maintains bright color vibrancy.
