Are there just two colours (gold and silver) that can be used for the scratch off technique? And do you need a special printer for printing scratch off inks?
Gold and silver are the most used colours for scratch off, that’s why these are the colours that suppliers tend to offer.
The scratch off effect is enabled by the fact that the ink has poor adherence to the material, therefore it comes off easily. So, all scratch off inks work when printed on UV coated sheets.
Indeed, UV coating isn’t compatible with the normal vinyl inks used in screen printing.
In short, you can use a vinyl ink like Serimat (in any colour) to obtain the scratch off effect, if you print on a UV coated surface, obviously.
However, it’s always advisable to carry out a preliminary print test to make sure.