Multicolour rubber in the same mould.
When different coloured buttons are wanted, we can spray paint them, we can produce different coloured buttons and then mould them together in the final mould, or we can include different coloured rubber in the mould itself.
Here I want to focus on different coloured rubber in the same mould.
The image shows three keypads which were compression moulded, with more than one colour of rubber in the mould.
In the top left example, blue with two red buttons, you can see that apart from making the two buttons red, some excess red rubber has also bled into the sides of the moulding.
To be on the safe side, there was a bit more red rubber than may have been strictly required.
However, because this moulding is eventually fitted behind a fascia on the finished product, these two red areas will be hidden, just the buttons themselves will be visible and they are wholly blue and red, as required.
The other two mouldings also feature multi coloured rubber in their moulds and their bleed areas are also are protected behind a fascia.
This technique works with compression moulding where the press operator can position the second colour of rubber such that the button will be filled with that colour rubber as the mould closes.