To produce a "quality" product the essential ingredient is a top quality raw material and this is one of the main reasons that Robson's have earned their reputation. Only the plumpest herring with the correct oil content are used to produce Craster kippers. The actual process of changing these "silver darlings" to the renowned kipper sounds a simple enough method. First, the herring are split on a machine capable of splitting 500kg per hour, this replaces the numerous "herring girls" that used to split the herring by hand.

Then the herring are placed in a brine solution of plain salt and water for a predetermined length of time depending on their size and, lastly, they are hung on tenter hooks and placed in the cavernous smokehouses. Fires are placed under the rows of herring made of whitewood shavings and oak sawdust and these smoulder away for up to 16 hours before the kippers are ready.