Nairobi, July 22 -- Every week, containers loaded with second-hand clothing land in Kenya, sustaining one of the country's most enduring informal industries. In them are tightly packed bales of denim that find their way to wholesalers in Gikomba, Nairobi, retailers in markets across the country and, ultimately, wardrobes of consumers looking for quality, branded jeans at a fraction of the price of new ones.

Morris Kamau first ventured into wholesale second-hand shoes before noticing demand for denim. Over the past 18 years, his business has grown to supply customers across Kenya and the wider East Africa.

"We import from the UK, Canada and China. The quality and price of the bale is determined by the country we source it from," says Kam...