The ASA said Brewdog told investigators that a single 330ml can made with the equivalent 330ml of pure gold, would have a gold value of about $500,000 (£363,000) at the time in October 2021, BBC reported.
"I had misunderstood the process of how they were made and the initial tweets I sent out told customers of the prospect of finding ‘solid gold cans'," Watt wrote in a LinkedIn post on Saturday (January 7).
The UK's advertising regulator upheld these complaints and said the false "solid gold" claim that was mentioned in three adverts was misleading.
"It was a silly mistake and it only appeared in around 3 of a total of 50 posts about the promotion but as it turns out, those 3 tweets were enough to do a lot of damage," Watt added.
“It blew up into a media storm. The gold can saga was headline news. The campaign launch morphed into a frenzy, with attacks coming in from all quarters. It got pretty grim. I should have been more careful
The Brewdog boss also admitted the initial tweets had been "misleading" and that the company "deserved the flak."
Watt then detailed how he contacted all 50 winners to "personally offer them the full cash amount as an alternative," if they were unhappy with their prize (the can and £10,000 worth of Brewdog shares).
"All in all, it ended up costing me around £470,000 – well over 2 and a half years ‘salary," he said, and jested how he is now the "proud owner" of 40 gold cans as a result of the "damaging episode."