Thank you for the reply I_d_allan, I think this is probably the way I will have to go.
I wrote to Canon also and thought their reply may be of help to someone...or maybe not
28/10/2013
Service Request:
1-1472513131
Thank you for your request and for contacting Canon.
We are sorry to read of your concern for the ink usage of your printer.
Ink may be used for purposes other than printing. Ink is not only used for printing, but also for cleaning the print head to maintain the optimal printing quality.
The machine has the function to automatically clean the ink jet nozzles to prevent clogging. In the cleaning procedure, ink is pumped out from the nozzles. Used ink for nozzle cleaning is limited to a small amount.
Black and-white printing may use ink other than black ink depending on the type of printing paper or the settings of the printer driver. So, color ink is consumed even when printing in black -and-white.
All our inkjet printers have a cleaning and maintenance routine to ensure that the printer is able to produce optimal printing quality. In essence it is one routine that is carried out at switch on, or if the printer has been switched on and not used for a period of time.
There are two kinds of black ink in the machine: dye ink (BK) and pigment ink (PGBK).
The dye ink is used mainly for printing photos, illustration, etc., and the pigment ink is used for text-based documents. Each has different purposes so that even if one runs out, another will not be used instead. If either of them runs out, the ink tank replacement is required.
These two inks are automatically used depending on the type of printing paper or the settings of the printer driver. You cannot change the usage of these inks yourself.
Detailed information on the specific page yield of your inkjet printer as well as the methodology used to measure page yields can be found by visiting the following link:
wwwdotcanondotcodotuk/ink/yield/
Please note that the measurements displayed in the link above may differ from your own since they have been conducted in one go without cleaning or turning on and off the printers used for the analysis. Naturally, this does not correspond with the normal usage patterns of home users.
Once again, thank you for contacting Canon Services & Support. We hope that the above explanations provide you with the necessary background information on the automatic cleaning processes Canon has put in place to guarantee the excellent printing quality of your inkjet printer
Yours sincerely,
Elaine Bannon
Canon Services & Support