I believe as long as the packaging is sealed your cartridges are good to use. I would be more concerned with the tiny nozzles on the printer itself gumming up through possible lack of use. Do you get any messages on the screen on the printer? A model number might be helpful in solving the issue too. Have you found the maintenance screen and done a nozzle cleaning and then tried printing a test page?

Thank you everyone for your responses. I just got back to the computer. Here are some answers to your questions. They are both inkjets. The oldest one is a Lexmark Z705. It is color and black, but I only use the black ink now since I got the other one. I don't remember when I got it, but it has been a long time, 4 years or longer. It is the one I use for the church printing and I use it a few times a month. The other is an HP PSC 1510xi that I got in 2006. I sue it frequently,but not heavily, for personal use. The Lexmark I never have to turn on or off. It automatically turns on when I click on print, and turns off when the computer turns off. The HP I have to actually push the button on the printer to turn it on and off, but I can't tell that it goes into sleep mode. The lights never dim. Anyway it sounds like I don't need to worry about it when I forget to turn it off. I think I just got a bad cartridge last time, because they usually last quite a bit longer. Thanks again

I soooo needed this. I stood in Michael's today totally confused - they're ink pads are 20% off this week - and came home with none. Actually, the 20% wasn't as good a deal as if I used a 40% coupon when they're not on sale, so I thought I'd wait until next week. Thank you so much for this list!!!

There are two chemical phenol-formaldahyde compounds, one in the paper and one in the pen The chemical in the paper + the chemical in the marker combine to produce the color. So the Crayola invisible ink markers will not work on anything except the chemically treated paper.