At 15.05 on Saturday (10 December), unit seven of the gravure superplant's second Cerrutti press flashed bright red as fire broke out inside. Around 10 seconds later, a second larger explosion was heard as unit eight flared up.

The fires were caused after the rubber covering on the press impression cylinder came off, exposing the highly charged electrical core, which arced, igniting the solvent.

"Gravure fires are relatively common," said Polestar Sheffield managing director Mike Young. "What was unusual about this one was that it continued to burn for around eight minutes."

Young promised "serious talks with our fire protection company" over the fire after fire sensors on the press, designed to flood the chamber with CO2 within eight seconds, took 25 seconds to kick in.
Ground crews had to attack the fires with handheld CO2 extinguishers after the internal fire protection system initially failed.

"That was a great training experience," Young said. "Our crews did a superb job. Fires do happen, and learning from this live experience will have benefited them."

The blazes were caught on CCTV footage from three different angles and shown to staff for training purposes.

"The CCTV footage makes fascinating viewing," Young said. "The whole enclosure lights up red."

The press was out of action for more than two days while pipes and impression rollers were replaced.