When the butter was removed from the churn the butter had to be 'grained' so that it was thick enough for moulding.
It was then washed several times in cold water and the buttermilk drained off. Once the butter was clean enough, butter pats were used to mould it into shape. The pats were dipped in water in between to avoid the butter sticking.
Butter sold in grocery shops came in large slabs. The grocer cut off a section and shaped it with the butter pats. Sometimes the butter was stamped with a design from a wooden mould.