This is a invisible code fresh from the printer, in the picture the ink has not dried yet, so you can clearly see that some thing was printed there. 

Using a 405nm LED on this code we get a bright and easily readable code, also the same code can be printed in the same area and lit with 780 nm IR and wold show as grey through a camera without an IR filter.

Using a workforce Epson W3700 printer I used fake ink cartridges and chips that trick the printer into thinking that the cartridges are genuine epson and also that the inks inside the cartridges are the correct type. In addition the chips also also never report empty, instead each time they are removed and re added they show full. This is very useful because these cartridges have rubber plugs that can be opened and refilled with the desired invisible ink.

I conclude printing the code was a great success that did not offer any issues once the printer was setup with the custom cartridges. My next test will be printing these onto clear matt stickers for use on the floor as well as furniture and other objects to be discretely marked.