A solution had to be found which would deliver a fluoropolymer lined vessel, able to withstand the repeated temperature cycling and offer the non-stick surface to encourage the gel to drop out.

Working closely with Northern Plastics in Bradford (part of the Ardeth group of companies), Holscot’s proposal was to create FEP/GRP vessels constructed using glass backed FEP, overwrapped with GRP. The two materials would form a homogeneous layer which would expand at a similar rate and avoid the problems seen with lined steel options. It was proposed that the existing stainless steel vessels could be cut down and part of them used as a support collar.

Northern Plastics provided a Mandrel onto which Holscot built the lining with FEP laminate exposing the glass fabric on the outside, Holscot used its proprietary welding and themoforming techniques to achieve this and Northern Plastics completed the vessel with multiple layers of fibre glass and resin to comply with the British Standard.

The completed trial vessel was subjected to the 1000 inversions without showing any signs of distress and Holscot/Northern Plastics went on to complete over 60 cauldrons.

In 2013, after nearly 20 years of service, Holscot has again been involved in manufacturing replacement cauldrons.