 Initially, the ink used was red, but it was found that this could be cleaned off and the stamps reused, and so after a series of experiments, early in 1841 black cancelling ink was used, which was more permanent.The color of the stamps was also changed to red-brown so as to ensure that the cancellation showed clearly.Britain soon abandoned the Maltese crosses and in 1844 began to employ cancellations displaying numbers which referred to the location of mailing.