A chemical plant with a 90-year history in a West Yorkshire town is to close with the loss of more than 300 jobs.
The plant's closure will be phased over the coming year
C6 Solutions, formerly known as Hickson and Welch, has blamed the weak US dollar and strong international competition for the decision.
The 140-acre site in Castleford will be closed over a phased period as existing contracts are honoured.
The Transport and General Workers Union said it would now fight for a fair deal for the staff being made redundant.
Union official Chris Emsen said: "It is a large site, a local site full of family and friends.
"There will be a lot of stunned disbelief in the plant when the finality does occur."
Managers at the C6 Solutions say the company has encountered market forces that have made continuing to trade "impossible".
Chief executive John Markham, said: "As a UK based manufacturer with customers almost wholly overseas, our trading has been impacted significantly by the weakness of the US dollar.
"In turn, this has assisted our overseas competitors, particularly low cost producers in the Far East and South East Asia, to take an increasing share of the markets we serve."
Mr Markham said the company had tried to work within the market conditions for as long as possible, but added: "Regrettably, our position is no longer sustainable.
"This is a sad day for everyone involved with the business."
The company was formerly known as Hickson and Welch
Yvette Cooper, Pontefract and Castleford Labour MP, said she would be meeting union officals on Friday to discuss the news.
"The closure is really sad news - especially after 90 years of chemical manufacturing in the town," said Ms Cooper.
"I'm calling for urgent support to help these skilled workers get new jobs before the plant closes."
The plant, which has roots at the site stretching back to 1915, was the scene of an explosion in 1992.
Five people died as a result of the fire, which was eventually brought under control by about 100 firefighters.