Stain Removal Precautions and Analysis of Factors Affecting Stain Removal

Stain removal is a highly technical job in the laundry industry. The quality of washing in a laundry shop largely depends on the stain removal skills of the operators. Removing stains thoroughly means the clothes themselves can be cleaned properly. A large proportion of laundry accidents are caused by improper or irregular stain removal operations. Even if some clothes can be restored after an accident, it consumes a lot of time, effort, and money, which is not worth it.
In actual stain removal operations, how can the clothes being treated avoid fading and deformation, achieve an ideal stain removal effect, and also avoid or reduce unnecessary accidents? This requires stain removal personnel to not only have rich experience and solid theoretical knowledge but also follow certain stain removal rules, understand and master some precautions during the stain removal process, and factors affecting the stain removal effect.
I. Stain Removal Precautions
(1) Do not forcibly remove stains
1. Analysis of situations involving forced stain removal
(1) Rough type. Generally, these are stain removal personnel who have just entered the industry and have not received formal training. They want to remove stains in one go in the shortest time possible, using great mechanical force, causing accidents such as color fading, pulling threads, damage, and style damage.
(2) Persistent type. They stubbornly continue with a method once they see some effect, determined not to stop until the stain is removed. Although there is some effect during stain removal, it leads to incomplete removal or damage to the clothes, without considering whether other methods could solve the stain.
(3) Careless type. Hastily removing stains without correctly judging the fabric, stain type, and stain remover properties is also a major cause of laundry accidents.
(4) Blind type. Using almost everything that can be found as a stain remover regardless of whether it works on the stain. The result is chemical reactions between various stain removers, either damaging the clothes or making the stain harder to remove, or stains that could have been removed become impossible to remove due to improper operation.
2. Stain removal should be based on existing technology
Chemicals and equipment should be used within their limits, without impulsiveness or blindness. It is better not to remove the stain than to damage the clothes.
(2) Correct judgment
1. Correct judgment of fabric
Make a relatively objective and correct judgment on the fiber properties of the fabric, color fastness, surface style, matching of decorations, and whether different colors affect each other. For example, stain removal for food oil stains differs greatly between silk and cotton-linen fabrics; polyester, nylon, and spandex-containing fabrics also differ from other fabrics. Note which fabrics cannot use certain stain removers, such as silk fabrics cannot use strongly alkaline stain removers.
Also pay attention to the color fastness of the fabric being treated and whether the mechanical force and stain remover will cause fading, such as pure cotton and silk clothes. These clothes often have poor color fastness, so the mechanical force and choice of stain remover must be controlled during stain removal to prevent color damage. The worst case is that the stain is not completely removed but the color of the clothes fades, causing color differences.
Some clothes have unique surface styles. Before stain removal, it is necessary to judge how to avoid affecting the style of the clothes and formulate a practical plan, so that the operator is clear before starting. For example, embossed, printed, or patterned designs made of rubber or plastic cannot use solvent-based stain removers.
Some decorations on clothes should also receive enough attention from stain removal operators, such as sequins and tassels. Acidic stain removers or oxidizers may cause decorations to fade, discolor, or fall off.
If a single garment has several colors with significant differences, color fastness tests should be conducted before stain removal to prevent color fading or color mixing caused by stain removal.
2. Correct judgment of stains
Only with a correct judgment of the stain can one know which stain removers and methods to use and which are harmful to the stain. For example, protein stains are difficult to remove after high temperature, and some tannin stains are hard to remove completely after treatment with alkaline stain removers.
3. Correct judgment of stain remover properties
Dry and wet stain removers should be used differently. One should understand the applicable range and usage methods of stain removers. For example, oxalic acid, chloroform, diluents, and hot alcohol damage acetate fibers and rayon; solvents cannot be used on coated clothes; silk and wool protein fabrics cannot use chlorine-containing chemical products for stain removal.
(3) Test before practice
For fabrics that are uncertain and unfamiliar stain removers, tests must be done first to see if they cause color damage or material damage before treating the stain.
(4) Proceed step by step
Proceed step by step from small to large, from shallow to deep, and from the safest method to the most dangerous method. Many stains require multiple repeated operations to be completely removed, so time must be allowed for the reaction. To determine effectiveness, first treat the smallest or lightest stain of the same type; if even the smallest or lightest stain is not affected, then change the method or switch the stain remover. The same type of stain may have several removal methods; the safest method should be chosen first. For example, if color-safe bleach can remove it, do not use chlorine bleach; if a conventional stain remover can remove it, do not directly use chemical products.
(5) Use clean water first, then stain remover
Except for stains like asphalt and paint, other stains should first be treated with clean water or conventional detergent; if they cannot be removed, then use a specialized stain remover.
(6) Use chemical reagents with caution
Before using chemical reagents, it is essential to fully understand their properties, applicable targets, and methods of use before applying them to clothing stain removal. Chemical reagents are a "double-edged sword" and must be used with extra caution.
2. Factors affecting stain removal effectiveness
(1) The impact of operation on stain removal
1. The impact of stain removal time on effectiveness
During stain removal, sufficient time must be allowed for the stain remover and stain to fully react; it is unrealistic to expect the stain remover to immediately decompose and completely remove the stain upon contact. Instant results are often seen but not all stain removals can achieve this ideal effect. Rushing is not advisable. The time required for stain removal is often overlooked by operators. They may apply one stain remover and switch to another before the reaction is complete. After using all available stain removers believed to be effective, the stain may still not be removed satisfactorily, resulting in helplessness, wasted time, and materials, and increasing the risk of stain removal accidents.
2. The impact of stain removal temperature on effectiveness
When stain removal effects are not obvious at room temperature, heating can be considered. Many stain removers react faster and more effectively at higher temperatures. Of course, raising the temperature during stain removal has certain prerequisites. It should be done appropriately based on the type of stain, fiber properties, and stain remover performance to achieve better results.
3. The impact of stain remover performance on effectiveness
Different manufacturers produce stain remover sets or chemical reagents with varying performances, resulting in different stain removal effects. In practice, for the same type of stain, stain removers from different manufacturers may have different effects. Even within one brand's stain remover set, some products may be particularly effective while others are average. Being skilled in using two or more stain removers not only reduces and avoids washing accidents and improves cleaning rates but also reveals some effects not listed in product manuals. These effects may be unknown even to manufacturers and are discovered by technicians during actual operation. Mastering two or more stain remover sets from different manufacturers allows complementary advantages and better overall performance.
4. The impact of stain remover concentration on effectiveness
The concentration of the stain remover affects both the effectiveness and the time required for stain removal. Generally, higher concentration shortens the removal time and improves effectiveness but also increases risk. For example, acetic acid above 23% can damage acetate fibers. For safety, the stain should be moistened with water before stain removal to reduce the concentration of the stain remover.
5. The impact of mechanical force on stain removal effectiveness
During stain removal, whether using rubbing, brushing, scraping, or spraying, mechanical force should be moderate and not applied violently or recklessly. Increasing mechanical force can improve stain removal and shorten time, but without understanding the fabric's nature and results, it can easily cause damage, fuzzing, pulling threads, or color differences.
(2) The impact of the fabric itself on stain removal
1. Fiber properties
Fiber properties greatly affect stain removal. For example, synthetic fibers can withstand greater mechanical force but are harder to remove oil stains from; cotton and linen have higher alkali resistance but are prone to fading; silk is more delicate with poor colorfastness and abrasion resistance, making stain removal difficult; stains on spandex-containing fabrics are also hard to remove, etc.
2. The impact of fabric structure on stain removal
In practice, fabrics with looser structures have stains that are relatively easier to remove, while tightly woven fabrics make stain removal more difficult.
3. The impact of finishing treatments on stain removal
Nowadays, many fabrics undergo various finishing treatments to achieve certain effects or meet requirements, such as stain resistance, water resistance, anti-static, flame retardant, wrinkle resistance, etc. Some finishing agents are water-soluble, others are solvent-soluble, which increases the difficulty of stain removal. Carelessness may damage the finishing agents while removing stains, causing loss of function or aesthetic appeal.
4. The impact of dye properties on stain removal
The color fastness of different dyes varies greatly. For example, the color fastness, chlorine bleach fastness, and sunlight fastness of direct dyes and acid dyes are very poor, while reactive dyes, vat dyes, and ice dyes have relatively higher color fastness. Sulfur dyes have very poor rubbing fastness. Coating printing and dyeing not only have poor rubbing fastness but are also damaged by solvents.
5. The effect of stain duration on stain removal
During the wearing process, if stains on clothes are not treated promptly, exposure to sunlight or oxidation reactions with oxygen in the air will increase the difficulty of stain removal, and may even make it impossible to remove.
Stain removal is a complex physical and chemical process that requires consideration of factors such as medium, temperature, mechanical force, and time. Methods such as dissolution, emulsification, oxidation, and reduction must be skillfully applied. Moreover, in washing practice, one must be diligent in exploration, courageous in innovation, continuously accumulate experience, and apply learned knowledge flexibly to gradually improve and enhance technical levels. Only then can the best and relatively safe stain removal effect be achieved.