Mr Haszard, the Dunedin-based founder of coffee and cinnamon liqueur Quick Brown Fox, has been working on the project for more than a year.
It had been a time-consuming process which required developing new equipment with the help of Farra Engineering and a friend.
Essentially, the result was a giant AeroPress; a very large 60-litre cylindrical chamber, used to make the concentrate, which was a delicate process.
Water acted as a solvent in the extraction of coffee. Tweaking any of those variables meant you could get a ''totally different'' end product, Mr Haszard said.
Cold water absorbed different compounds from the coffee than a hot, pressurised extraction.
Harpoon was made through full immersion cold brew then filtered to 20 microns with gentle pressure.
The result was a very delicate brew which tended to be sweeter, toastier and less bitter, and it was ''wonderful'' on a hot day, he said.
It was versatile, as it could be diluted, with the likes of milk or water, or used in espresso martinis, or coffee soda. As it was sealed with a nitrogen purge, it would keep for three months unopened in the fridge and two weeks once opened.
Mr Haszard had been keeping a close eye developments in the United States and Europe over the summer and had seen plenty of innovation in cold brew. While it had been particularly big in the US, it was still relatively new in New Zealand.
A ''handful'' of cold brews had been made by cafes over the last couple of years, he said.
In summer, when people did not necessarily want a hot coffee, Harpoon could be just the thing, he said.
It had already been trialled in three bars: Carousel in Dunedin, Madam Woo in Queenstown and My Bar in Auckland, with favourable responses, he said.
In Dunedin, it was stocked at Morning Magpie, Strictly Coffee and Veggie Boys.
