Iteration IV focuses on the longest, the most complex and least understood process of maturation. Casks filled with new make spirit undertake years and decades of interactions with their environment, building an unpredictable structure for the whisky to come. Those who lay the casks down, pass them to a future generation, who will be the custodians of the results. The seasonal cycling of temperature and humidity, warehouse type and location, combining with the angels, to give us significant complexity to manage. Casks have been sought from the darkest, coldest locations in Bladnoch’s warehousing to amplify these effects in the Iteration IV.