Interesting question……. Actually it’s not just with jeans. Every cotton made fabric shrinks, maximum with first wash and to some extent with every wash. Cotton thread used in fabric weaving is spun to high counts to give it strength and fine neat look. This is important in fabric manufacturing. When this fabric is first time introduced to water, the cotton swells and got compact due to those thread twists. This phenomenon increases the quantity of cotton per square inch of fabric and reduces the length and width.
Why jeans shrink more??
It’s same in cotton jeans but with one more additional factor, that is de-sizing of jeans. When denim is made, its warp thread is sized (starch coated) to avoid its breakage during weaving process. This starch gives a rigid and rough character to denim. In first wash when this starch is removed (commonly starches are water soluble and washed off in simple rinse) fabric comes back to its relaxed position and shrinks in all dimensions. This combine effect of cottons natural swelling and de-sizing collectively gives extra shrinkage in denim jeans and gives special character to this wear.
How mixed cotton jeans shrink?
Jeans comes in multiple combinations. Cotton polyester blended jeans shrink less as compare to pure cotton jeans. This fabric combination is always mentioned in labels inside jeans. Never forget to look at that when buying a pair. In stretch denim, elastasince is mixed with cotton to give stretchy character and here the shrinkage didn’t remain important (stretch covers the cotton shrinkage when mounted on body).
It is mostly pre shrunk denim in market
Well, Thanks to jeans manufacturers, the jeans that you find in market are pre-shrunk and contain its specs. After washing it will shrink to some centimeters but after wearing you will find it coming back to original fit (after walking around for some time)
IMPORTANT: Raw Denim Jeans is not pre-shrunk …… when buying Raw Denim Jeans, IT WILL SHRUNK as elaborated above. So it is important to know that you have to buy it little lose……..