Why does nobody talk about the coolant mix being off by just a few percent?

I've seen three shops in the last six months where guys were having rust issues on finished parts, and every time it came down to the coolant concentration. They were checking it with those cheap refractometers that hadn't been calibrated since they bought them. My old boss in Toledo taught me to check it with a proper test strip every Monday, and to write the number on the machine with a grease pen. A 5% mix instead of an 8% mix might not seem like much, but it's the difference between a perfect finish and a part that gets sent back. It eats up your tools faster too. I keep a bottle of calibration fluid in my box just to be sure. Anyone else run into this, or have a better way to keep the mix right?

2 comments

2 Comments

iris56513d ago

Yeah, those test strips can go bad too if they get old or sit in a hot toolbox. I had a pack that was reading way low, gave me a scare. The calibration fluid is the only thing I really trust now to check my checker, you know?

emeryp2313d ago

Tell me about it, I learned that lesson the hard way. Ran a whole batch of aluminum parts that came out looking like they'd been buried in my backyard. My refractometer was lying to me by like three points. Felt like a real genius explaining that to the boss. Now I'm paranoid and check it with strips too, even though it makes me look like a pool boy testing chlorine. That calibration fluid is a good idea, I should grab some.