Hi Charley, the ink used in the cartrides, the ink i used was some left over from my old epson printer, and i thought rather than waste the ink i would experiment with it, you only need the basic 4 pigments, magenta,cyan,yellow and black, and you can virtually make up any shade of colour stain you want, i only recommended the pigment inks as they are more fade resistant than the dye based inks, although with the dye based inks the colours are slighty richer in their colour, both are available in bulk and are relatively cheap, compared to buying pre-coloured stains, plus you only need to mix enough for what you need at the time, it's all good fun, cheers,