Insolvency practitioner Mazars was appointed as administrator, while the company's 10 staff have been made redundant.
According to Unite, the returning employees were unaware that the company was suffering any financial problems.
Steve Ireland, national officer at Unite, told PrintWeek: "The staff returned to work after Christmas to be told that the company was planning to close and they were given forms to make their claims.
"Some of the guys have been with the company for 20 years – they didn't see it coming – they were shocked."
However, several employees have found work with local printer Annodata Print Services and have taken the company's phone number with them.
When PrintWeek attempted to contact Prism, the call was routed to Annodata and answered by an employee who confirmed that a number of Prism staff were now employed there.
Mazars was not available for comment.
Prism Digital Colour staff stunned by closure
Employees at Luton-based digital printer Prism Digital Colour were left stunned when they returned to work after Christmas to be told the company was announcing its closure.