Washing linen is a careful work. While using the washing chemicals correctly, the second is the washing process. The whole process of linen washing should include inspection and classification, stain removal treatment, pre-washing, main washing, rinsing, watering, dehydration, The content of process operations such as peracid neutralization, softening, sizing, drying and ironing. However, the purpose of the fabric is different, the material is different, and the soiling condition is different, and the main process and operation content of the linen washing should also be different.
Check classification
Checking and sorting is the first step in washing linen. For linen sent from hotels and hotels, the packaging should be opened and shaken separately before washing. Check the sheets for blood stains, fruit stains, etc.; towels, pillow towels, etc. Whether there is hair gel, shoe grease, etc. on it. In case of stains or heavy soiled fabrics, they should be pre-treated for stain removal first; in case of damaged fabrics, they should be registered or treated separately.
The linen delivered to the laundry factory is very diverse. In order to ensure the washing effect, the linen inspection process should be classified and stored according to the color of the fabric, the soiling condition, and the material of the linen, and make preparations before washing.
The inspection and classification of linen before washing is a monotonous and cumbersome work. Although its technical content is not high, it has a great impact on the washing effect. If it is careless, it needs to be washed back, causing unnecessary waste; Cause compensation and bring economic and reputation losses to the laundry.
Stain removal
Most of the newly stained stains and dirt on the washed linen can be removed after the main washing, bleaching, and overwatering. Such as: water-based stains in juices, beverages, etc., neutralize the peracid with alkaline washing liquid, and bleach with chlorine bleaching or color bleaching to remove pigments, and then pass water several times to basically remove them.
The large area of grease and protein dirt newly contaminated on the linen shall be adjusted by the washing process (warm washing or cold water soaking), using appropriate washing materials (adding emulsifier and strong washing powder to the washing liquid, etc.), It is easy to emulsify, decompose, disperse and suspend it in the washing liquid, and then bleach, overwater, and most of it can also be removed. However, some old stains and oily pigment stains, etc., require special stain removal treatment to remove them.
Prewash
Pre-washing is the preparation stage before the main washing of the linen, which is good for improving the washing effect and reducing the amount of detergent. Its function is to moisten the fabric and dirt with water. At the same time, under the combined action of the impact of water and the repeated rubbing and beating of the washing machine, some dirt such as salt, sugar and other water-soluble dirt, blood stains, sweat stains, juice, etc. newly contaminated on the fabric are removed. Dirt such as beverages and some solid particles such as sand, dust, etc., are partially or completely removed.
Pre-washing is often regarded as a dispensable process operation by some friends and is not taken seriously. Some washing plants directly perform the main washing for the sake of convenience. As a result, some stains that are easier to remove are used in the main washing at high temperature. The bottom becomes stains, causing a lot of stains on the fabric after washing. Although repeated alkaline washing, acid neutralization, chlorine bleaching or color bleaching, and even the use of professional stain removers, it is still useless. Such lessons are worth learning and reflection.
Main wash
The main washing is the most critical technological operation in the washing process of the linen. Through the main washing, the dirt contaminated on the linen fabrics can be removed as much as possible, dissolved, emulsified, dispersed or suspended in the washing liquid. The main washing load should be controlled at 85% (100kg washing machine). Excessive loading of linen not only does not wash clean, the water is not thorough, but also increases the cost of the washing plant.
However, due to different fabric materials, in order to obtain the best washing effect, the most favorable washing conditions must be selected based on various factors that affect washing, such as: physical and mechanical effects during washing, chemical effects of detergents, washing temperature and The washing time, etc., and the corresponding washing program shall be formulated at the same time to complete the main washing process safely and smoothly.
rinsing
Rinsing is also bleaching. After the main wash, although the dirt on the linen is basically peeled off, some stains are affected by many factors, and the formed color base still remains on the fabric. For this reason, bleaching treatment is required to increase the whiteness of the washed white fabric and make the color of the colored fabric more vivid. Commonly used bleaching agents in bleaching include oxygen-releasing oxygen bleaching powder or liquid, and chlorine-releasing chlorine bleaching powder or liquid. After they are decomposed in the water, they can release nascent oxygen with strong oxidizing ability, thereby destroying the pigment genes and disappearing the color background.
It is worth pointing out that due to the different materials of the fabric, the physical and chemical properties such as acid resistance, alkali resistance and antioxidants are very different, and different types of bleaching agents have the best bleaching temperature, concentration, and ph of the bleaching bath. The value and the effect on fabric strength and color are also very different.
For this reason, the ideal bleaching effect can be achieved by selecting bleaching agents and their dosages reasonably, and correctly mastering the operating conditions of the bleaching process. Oxygen brand detergent can combine the main washing and rinsing, and adding one in the main washing can achieve the effect of decontamination and bleaching.
Water throwing and dehydration
After the main washing and bleaching, the linen generally goes through a medium-speed or high-speed dehydration process to minimize the residual washing liquid in the fabric and improve the bleaching efficiency of the washed fabric. The washing liquid remaining in the fabric contains both alkaline detergent and dirt that has fallen off the fabric. In order to obtain the best washing effect, a certain amount of water is needed to dilute the washing liquid on the fabric, and through the physical action of the washing machine, the detergent and dirt on the fabric are further diffused into the clean water.
In order to accelerate the diffusion effect, try to dilute the residual washing liquid in the fabric, and often use high water level for water injection, and do it many times to gradually reduce the concentration of the residual washing liquid on the fabric. The material of the fabric is different, the degree of compactness of the structure is different, the main washing and bleaching chemical raw materials and their dosage are different, and the number of water rinsing should also be different. Generally, pure cotton fabrics with strong water absorption properties, especially towel fabrics, usually need to be rinsed with water for 3-4 times, while chemical fiber fabrics with poor water absorption properties are usually rinsed with water for 1-2 times to meet the requirements.
In order to keep the fabric fibers in a swollen state during water rinsing, to facilitate the diffusion of the washing liquid from the fabric fibers, and to avoid the wrinkles of chemical fiber fabrics that are difficult to iron due to the sudden drop in temperature, the gradient should be maintained during water rinsing. decline. As for the time required for each water rinsing, it should be based on the capacity of the washing machine and the material of the washed fabric, etc., usually about 2-3 minutes.
After the washed linen is thrown into water, in order to reduce the moisture content of the fabric as much as possible and speed up the drying speed of the fabric, a high-speed dehydration is required. However, when fabrics are dehydrated, not only the effect of high-speed dehydration on the moisture content of the fabric should be considered, but also the damage that the huge centrifugal effect of the washing machine may cause to the fabric. For this reason, the material and structure of the fabric are different, and the time for high-speed centrifugal dewatering is also different, usually about 6-8 minutes. High-speed dewatering is not suitable for wool fabrics and delicate fabrics with light materials and loose structures.
Linen washing may affect the quality of the linen in any process. From the water quality treatment, the choice of chemical materials, and the washing process, the impact on the quality of the linen is very critical.