Slashing involves coating warp yarns with a starch-based solution known as sizing. This coating provides additional strength to the yarns, allowing them to withstand the friction generated during weaving. The process also creates a smoother surface, which reduces yarn breakages during weaving.
Sizing is applied to warp yarns before they are woven. It consists of a mixture of ingredients such as starch, additives, waxes, and lubricants, designed to enhance the yarns' strength, flexibility, and resistance. The yarns are passed through a sizing machine where the sizing solution is evenly applied.
Here are the key steps involved in slashing or yarn sizing:
1. Preparing the sizing solution: The sizing ingredients, including starch and other additives, are mixed with water to create the desired sizing solution.
2. Soaking the yarns: The warp yarns are immersed in the sizing solution to ensure complete penetration of the sizing material into the yarns.
3. Drying the yarns: After soaking, the yarns are guided through a drying chamber or oven to remove excess moisture and set the sizing.
4. Conditioning: The dried yarns are then subjected to a conditioning process where they are exposed to controlled temperature and humidity to ensure even distribution of moisture throughout the yarns.
5. Cooling and beaming: The conditioned yarns are cooled to room temperature and then wound onto a beam, ready to be used in the weaving process.
By reinforcing warp yarns with sizing, the slashing process reduces the number of yarn breaks, which leads to increased weaving efficiency and reduced fabric defects. It also improves weaving speed, yarn quality, and overall fabric performance.