Printing on a Dot Matrix printer

I am working on a PHP / MYSQL based application and am using epson LQ - 300 + II dot matrix printer for printing the credentials of the system on a 2 ply paper.

These are specially designed slips on which the following information is shown :

1.Company Name

The slips are designed in a way that the company name should be printed in a normal area whereas the Username and password should be printed in a blackened area so that it is not seen.

The problem i am facing is inspite of printing on that blackend area , the font is still visible . I have tried making the font white of the username and password but it doesnt help . Tried different fonts from the application and from the printer settings as well but didnt work.

The solution i can see is printing the credentials on using small font size but still that is also not full proof as still the information is readable through naked eyes and am sure it would be very obvious and readable through a magnifier.

So can anyone advise on how can the printing be done using the above printer and a 2 ply paper - please note that the entire slip is carboned.

If you’re printing on an impact printer, then there will be no way to avoid those items being visible - someone can simply do a rubbing and get the “blackened” out items.

A better approach would be not to print the items at all - add a print style sheet which doesn’t show those items on them, and hence, no impact for the items to be copied.

DaveMaxwell’s idea is best, set up a special print css file if you can.

If the output it rendered as HTML on a browser, and for some reason you cannot set a print.css file, then render the user/pass as <input type = password > and it should display stars. (but if you can do that, well, you can hide them completely cant you?)