In this classic sticky-rice western, Jackie Chan finds himself locked up, stressed out and desperate. The year is 1881, and Chinese princess Lucy Liu has been kidnapped in Nevada. Imperial guardsman Chan)has set off to the wild west to rescue her. After hitting it off (literally) Jackie and gunslinger Roy (Owen Wilson) find themselves behind bars.

 

Ancient Chinese teachings dictate that urinating on fabric will strengthen it, and Jackie is able to enact a brilliant escape using a shirt, a wooden stick and, you guessed it, wee. But is this possible? Our two presenters are determined to find out.

To repeat the jail breaking feat, our hosts, being of a somewhat delicate constitution, don’t want to use their own urine, so they construct some using chemicals and household ingredients.

As you can see urine is 95% water, so what effect does water have on the strength of cotton?

Cotton is 99% pure cellulose. Cellulose molecules form long strands that repeat, forming the fibre that makes up cotton.

Cotton is actually stronger wet than dry. This occurs because the hydrogen atoms in the water create extra bonds with those of the cellulose.

Cotton cellulose has a high degree of polymerization and a high degree of crystallinity.

Crystallinity means that the fibre molecules are closely packed and parallel to one another.

The higher the crystallinity and polymerization in polymers, the stronger they tend to be. The cellulose chains within the cotton fibres are held in place by hydrogen bonding. These hydrogen bonds occur between the hydroxyl groups of adjacent molecules and are more prevalent between the parallel, closely packed molecules in the crystalline areas of the fibre. When the cotton is wet, the water present forms additional hydrogen bonds increasing the strength of the cotton.

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