What happens if I fill PGI-520BK with CLI-521BK ink?

[OM2]

My laser toner run out!
So I had to use my old Canon MX870.
PGI-520BK was empty.
I had ink for all cartridges apart from PGI-520BK.
So I refilled with CLI-521BK ink.

Just wondering if that's a bad idea?
It got me out of prison for today.
If not a good idea, I'll get stock of PGI-520BK ink.

Thanks.

 

[palombian]

PGI stands for pigment ink used for text printing, the other carts contain dye ink (CLI) for photos.
The reason is dye ink is absorbed in the paper and will make the letters less sharp.
You will not harm the printer, only have reduced quality for office documents.

 

[PeterBJ]

The pigment ink is waterproof, the dye ink is not, so dye ink is not suitable for adresses on envelopes and labels that might become moist.

 

[OM2]

Thanks for confirming guys.
I thought it might clog the cartridges or something.
Many sellers sell just 4 inks - I always wondered why they didn't sell 5.
I understand better now.