The King has jokingly refused to shake hands with a blacksmith whose hands were dirty.
Charles met Ian Thackray during an engagement for The King’s Foundation at his Highgrove home in Gloucestershire.
Mr Thackray, who trained a decade ago with the then Prince’s Foundation, helps mentor blacksmiths coming into the industry.
Speaking afterwards, Mr Thackray, from Dorset, said: “I said to the King it was nice to see each other again as I had trained through the Prince’s Foundation and we have bumped into each other a few times over the last 10 or 11 years.
“The King has only seen me in a suit and tie. He politely declined to shake my hand as it was black from charcoal dust.
“We are friendly enough to have a joke about it.”
In the brief exchange, Mr Thackray showed Charles some of the things he has been working on recently, including ancient Egyptian necklace beads which have been made from meteorites and replica lanterns produced for RHS Wisley.
During the visit, the King also chatted with members of a Tetbury choir who were singing Christmas carols and invited him to join them at one of their weekly sessions.
Charles also tried a glass of festive mulled cider as he chatted with local producers.
Taking a sip from a glass, the King said: “Marvellous – that’s a new discovery.”
Charles also met graduates and tutors from The King’s Foundation’s craft programmes, including the Metiers d’Art Fellowship, the School of Traditional Arts, and the Building Arts Programme.
Around 15,000 students take part in the foundation’s education programmes each year and many are involved in courses that teach traditional arts and crafts.