Here is a little excerpt re pressed horn taken from the supplement to The Penny Magazine, April, 1844 entitled A Day at the Sheffield Cutlery Works
"Horn handles have a peculiarity in their mode of manufacture, which places them in a distinct rank. When horn is made hot, it becomes so soft and ductile that it may be pressed into moulds; and this circumstance is taken advantage of to give an ornamental device to horn handles....The mould for pressing is in two halves which close together like a pair of pincers. The mould is heated in a fire; the piece of horn is cut nearly to the requisite size, and put into it; and the mould is pressed in a powerful vice, whereby the horn receives the impress of the device. "