forcing grayscale output on colour printer

[Donald]

Hi,

We have a networked Tektronix Phaser 850, which we can happily send postscript print jobs to using a raw HP JetDirect connection. I'm running Ubuntu Linux 5.10, and I want to be able to force a grayscale output from the printer. This is to save toner - colour cartridges are expensive. I thought I'd be able to select the default grayscale postscript PPD file, but that doesn't work. I saw somewhere else that might be due to the fact that it will leave documents already supplied as PostScript untouched. Is there any way to pre-filter the postscript file to convert it to grayscale before it is actually sent to the printer?

Any help appreciated.
Thanks
Donald.