Prince Charles buried two jumpers to encourage people to buy more wool products.
The 67-year-old royal opted to bury one woollen jumper and another made from synthetic fabric to show how environmental friendly wool is.
He shared: "Six months later, a ceremonious exhumation revealed an intact synthetic jersey, fit indeed to be washed and worn, while the woollen jersey had quietly and usefully biodegraded itself away to nothing."
The Prince of Wales - who is first in line to the throne - also conducted a fire test on the two jumpers, showing how the synthetic fibre caused a "dramatic and disconcerting blaze".
He added: "Synthetic jerseys produced a dramatic and disconcerting blaze. While their woollen counterparts merely smouldered in relative safety."
The Prince wants the tests to "encourage a much greater understanding of wool".
Writing in The Telegraph magazine, he added: "I want to encourage a much greater understanding of wool not only as a global environmental resource - versatile, sustainable, renewable and natural - but also as a global fashion resource of the highest quality.
"These may not be entirely welcome propositions in some part of an industry that is sadly dominated by mass-produced chemical fibres, but today's environmentally aware consumers do seem to be seeking out quality and durability in fashion, lifestyle and interiors. And that is exactly what wool provides."
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