Ink viscosity sounds fancy, but it’s really about thickness—like comparing honey to water. You’d think it’s simple. Yet ask any press operator and they’ll tell you it can make or break a press run. You know what? It’s funny how this small detail trips people up. Viscosity determines how ink flows, transfers, and ultimately sticks to your substrate. Too thick? You risk piling, poor transfer, and clogged anilox cells. Too thin? Say goodbye to opacity and hello to color drift. I once set up and started running a job that looked fine in the morning. By early-afternoon, with the shop heating up, the ink turned syrupy. Total mess. The supervisor blamed me. I blamed the ink. The ink rep, whose number I just happen to have saved on my cell, blamed the humidity. In reality, it was my fault. I hadn’t bothered checking viscosity again after lunch. I saw the ink pans were still full of ink, so I fired up the press and ran!

It’s like cooking, really. Gravy that’s too thick sticks to the ladle; too thin and it runs off your plate. The press doesn’t care about your excuses—it just shows you the result. Humidity and temperature swings are big culprits. Summer can be brutal for water-based inks, which soak up moisture like a sponge. Winter might seem easier, but don’t get too cozy—it can still mess with your setup.

So why care? Because consistency is money.

Downtime from defects costs you reruns, wasted stock, and operator headaches. Even your customer notices when colors don’t match last month’s shipment. Honestly, taking 30 seconds to check viscosity before a long run saves hours of grief. It’s one of those “ounce of prevention” deals. So, next time you’re prepping ink, think about it. Give it a quick check, adjust if needed. And during the run, check it again. And again maybe. Your future self will thank you—and so will your bottom line.

Want to learn how to measure and manage viscosity on press? Stay tuned for Part 2 of this series!

PS…Honestly, if not for the drip tray liners I had underneath my ink stations, that day would have been a lot worse!