Warp yarn is cut by knife and the white weft yarn is left in place to create a beautiful worn out effect. The garment with cuts is then washed in washers to reveal the white the white thread. This make the horizontal white lines of weft and if some dye is added to wash bath it will add more beauty to the garment. The secreat is the cuts are always kept weft wise i.e in horizontal to the garment. This will keep the weft in place and warp will be removed in washing process. If it let the warp is cut then the only thing you get after wash is a big hole.
Ripping and pilling are technically difficult operations to execute. If the garment is rubbed with sand paper form a specific area by keeping a hard sport under the fabric then this results to ripping effect. The rubbing is done in a way that only the warp is partially damaged and weft keep in place. The intensity of rubbing is much greater than we do for normal sand blasting effect and to the extent where the warp is damaged. This partially damaged warp will let the weft to expose in some areas and a contrast of white and blue will appear there. The idea of the ripping is the effect of rubbing off of jeans with a concrete wall or stone.
Pilling is typically done with sharp edges of hard metal wires. The process is to break the white weft between the dyed warp. This process after wash will result to the tiny broken edges of white weft peeping through the colored warp. The weft will only be exposed when you drive the tool warp wise that is horizontal to the weft. This is again the horizontal direction of the garment. If the tool is driven weft wise then the broken thread is died warp, the polling will again appear but due to absence of color contrast it will not be clearly visible.