"We commenced our talks but got nowhere, and the company still wanted to force redundancies," said GPMU deputy general secretary Tony Burke.
A further 48-hour stoppage is planned for next week, which the company has been notified of by the GPMU.
Workers had been set to strike after threats of 100 job cuts by management (PrintWeek, 29 April).
Industrial action was originally averted at the eleventh hour on 26 April after management agreed to meet GPMU officials for discussions, which included union recognition at the plant.
Burke said that the union had wanted to talk to the company to resolve issues, but he said it soon became clear that discussions were going nowhere.
"In the local media the company is saying we are intimidating them, but we are just seeking meaningful discussions," he said.
"They are treating the workforce in an appalling way, with some of the staff working 70 hours a week on minimum wage," said Burke.
The firm was unavailable for comment.
Story by Andy Scott
