The union of the printers industry is taking industrial action after losing its contract with the National Union of Paper Mill Operators.
The company said the strike was not related to the current dispute with its local union.
The printers union has been locked in dispute with the British Paper Mill Association (BNPA) for a number of years, with the two sides having been locked out of talks.
The BPA, which has about 3,000 members, represents about 10% of the UK’s paper mills.
The union said the dispute is related to “contractual issues which have been ongoing for some time”.
It said it was seeking to negotiate a fair contract and “to ensure the right conditions are in place for the future”.
The printer union has said it will “not accept a reduction in pay or conditions for those who work in our factories” and it is calling for a boycott of the company.
The National Union is also campaigning against a decision to axe its contract in the paper industry.
The unions union said its members were “unprepared” for a strike on Saturday.
It said: “We are not prepared to be put in a position where we have to lay off our members, who have worked for years for free, because the company is refusing to negotiate for a fair and sustainable contract.”
Our members deserve to be paid at least the minimum wage, and we are calling on our members to stand up to the company.
“The National Paper Mill Union has been campaigning for 10 years to win a contract for the industry, which relies on a reliance on a single supplier for its raw material.
The group, which represents about 20% of UK’s printers, is one of the few unions that has been able to hold the British paper mill association and the union that represents its suppliers to account over the past decade.
The NPUU said: The unions strike is not related in any way to the ongoing dispute with our suppliers, and this strike is being taken to protect the health of our members.
We have a very clear position on pay and conditions for our members and we have the support of the other unions and trade union organisations.
It has been reported that the company has also threatened to pull out of negotiations unless a contract is agreed.
In January 2016, the union agreed a contract with its suppliers that would see it pay £150m in benefits over three years.
It is understood the company would not agree to a new deal until the NPUUs pay of the next three years has been paid.
The trade unions union says it will not accept a cut in pay and will instead “continue to support the workers”.