Tired of Covid? Over the next few months we are going to look into our services offered, giving you insight about what we do and why we do it. A little distraction from what is going on in the world.
Calendering of Fabric, what is it?
Calendering is a mechanical finishing process used on cloth where fabric is folded in half and passed under rollers at high temperatures and pressures. Calendering is used on fabrics such as moiré to produce its watered effect and also on cambric and some types of satins. But what is calendaring really? Calendaring is a high speed ironing process that primarily imparts lustre and is usually the final treatment for the fabrics in the finishing sequence.
The basic principle of calendaring is to expose the cloth to the combined effect of moisture, heat and pressure until the fabric acquires a very smooth and light reflecting surface and gets a good lustre. The calendaring effect on the fabric is usually temporary and disappears after first washing. Semi-permanent lustre is sometimes achieved by padding fabric in a sparingly soluble polyvinyl acetate emulsion before calendaring, where the solution acts as a binding agent. More permanent finish can be obtained by treating fabric with a solution of crease recovery reagent, followed by drying, calendaring and curing the fabric at about 150 ºC. The calendars are basically an assembly of heavy rolls, alternatively of iron and paper or cotton that are normally mounted in vertical frames. The rolls are bearing one on the other under a high pressure that is applied by compound levers or hydraulic or pneumatic equipment.
Why is it important you ask? In the case of textiles, finishing is accomplished through either the padding or the exhaust process. Textile finishes are important because they help to improve the appearance; they also make the fabric more useful and suitable for an end (specific) use.