With the development of garment industry, the new materials, new processes, washing processes and post-treatment methods of garment products are more and more diversified. However, it should be noted that a variety of treatment methods may easily cause discoloration of metal zippers' teeth and pull-heads, or cause staining transfer of metal zippers during washing or post-treatment. This paper analyzes the causes of discoloration of the following metal zippers and the preventive measures that can be taken to eliminate or prevent discoloration.
Chemical reactions of metals
Copper alloys are known to react with acids, bases, oxidants, reducing agents, sulfides and other chemicals, causing discoloration.
Black teeth metal zippers are prone to discoloration due to chemical residues in the fabric, or when chemicals are added during washing. Chemical reactions also occur easily between fabrics containing reactive dyes and copper alloys.
Chemical reactions tend to occur in high temperature and humidity. If the product is put into plastic bags immediately after sewing, washing and steam ironing, and stored in plastic bags for a long time, the metal zipper is easy to change color.
Wool and cotton fabrics discolour during washing
Discoloration occurs if copper zippers are attached to bleached wool fabric. This is because the chemicals involved in the bleaching process are not fully purified or neutralized, and the fabric releases chemical gases (such as chlorine) that react with the zipper surface in wet conditions. In addition, if the finished product is immediately bagged after ironing, it will also cause the discoloration of zippers containing copper alloys due to the volatilization of chemicals and gases.
Measures:
Thoroughly clean and dry the fabric.
The chemicals involved in the washing process should be adequately cleaned and neutralized.
Packaging should not be carried out immediately after ironing.
Discoloration of leather products
Brass metal zipper open ends can become discolored by residual substances from tanning agents and acids used in the tanning process. Leather tanning involves various tanning agents, such as mineral acids (such as sulfuric acid), tannins containing chromium compounds, aldehydes and so on. And leather is mainly composed of animal protein, the liquid after treatment is not easy to handle. Due to time and humidity, contact between residues and metal zippers can cause metal discoloration.
Measures:
The leather used should be thoroughly washed and neutralized after tanning.
Clothing should be stored in a ventilated and dry environment.
Discoloration caused by sulfide
Sulphide dyes are soluble in sodium sulphide and are mainly used for cotton fiber dyeing and low-cost cotton fiber blended fabric dyeing. The main variety of sulphide dyes, sulphide black, reacts with zippers containing copper alloys at high temperatures and humidity to form copper sulphide (black) and copper oxide (brown).
Measures:
The clothes should be washed and dried thoroughly immediately after treatment.
Decoloration and discoloration of reactive dyes for sewing products
Reactive dyes used for dyeing cotton and linen products contain metal ions. The dye reduces with the copper alloy, causing decoloration or discoloration of the fabric. Therefore, when reactive dyes are used in products, zippers containing copper alloys tend to react with them and discolor.
Measures:
The clothes should be washed and dried thoroughly immediately after treatment.
Separate the zipper from the cloth with a strip of cloth.
Corrosion and discoloration of garment products due to dyeing/bleaching
On the one hand, garment products in the zipper industry are not suitable for dyeing because the chemicals involved can corrode the zipper metal parts. Bleaching, on the other hand, can also corrode fabrics and metal zippers.
Measures:
Garment samples should be dyed before dyeing.
Wash and dry clothes thoroughly immediately after dyeing.
Attention should be paid to the concentration of bleach.
The bleach temperature should be kept below 60°C.
Post time: Jul-25-2022