If the buyer of the artwork decides to make prints of the work, then they have to ask permission from the artist and then is responsible for paying an agreed royaly to the artist. Copyright always remains with the artist unless they sell the copyright - normally about 4 times the price of the original. As for the artist making his own prints it goes along these lines. Limited edition prints have to be numbered, so there is a record of how many there are. If you buy a print that is numbered say 35 out of 250 and then discover that the artist has printed 450, the artist then has a case of fraud to answer to. When you buy one of these prints, you are paying a premium because you can be sure you will not see the image splashed everywhere - exclusivity I guess ( however,there are other factors to take into account). This only applies to Limited edition prints. The artist doesn't have to sign the print and if they decide not to, it renders the print far less valuable then if it were signed. There is no obligation for the artist to date anything, doing so is only helpful in giving a chronological record.
