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  • Hal Rogers

Metalworking fluid - my advice? Don’t feed it and don’t let it out.


Metalworking fluid - my advice? Don’t feed it and don’t let it out.

Metalworking fluid is dangerous if you don’t look after it. It can cause permanent harm to your breathing and cause your skin to split. Your doctor cannot prescribe anything to make you better.


Don’t feed it

Metalworking fluid is a hazardous chemical in its own right, but you can make it ten times worse by allowing bacteria to grow in it. There will always be bacteria looking for an easy life. They are in the air everywhere. It’s a fact of life.

  • Don’t give them extra food. Keep the metalworking fluid clean and free from tramp oil (oil leaking from the machine). Never throw paper tissues, Costa cups or McDonalds wrappers in the sump.

  • Keep a beady eye on them. Take “dipslide” samples every week. If you have bacteria, they will form tiny red spots on the dipslide after a couple of days. If the spots join up, or cover the dipslide, then your bacteria are winning, and you need to come down hard on them.

  • Sniff out troublemakers. Every shift, check the sump smell for anything like rotten meat. Get it cleaned out.

  • Bubble party! Bubbles in the sump mean your bacteria are having a party. Get rid of them.

Don’t let it out

The idea is to not share your air with the bacteria. If you breathe in the bacteria or their waste products, your body may go into an allergic ‘I-won’t-let-you-in’ or ‘get-it-out-of-me’ mode and give you asthma or hypersensitivity pneumonitis.

  • Enclose the machine as much as possible. Your machines may have full enclosures, or you may need to add extra panels.

  • If fixed barriers are not possible, drape cloths over the machine to catch the mist.

  • To stop mist of the sump contents from escaping into your airspace, use an extractor to suck the mist back into the machine. Extraction does not work very quickly, so give it a chance to clear the mist before opening the machine’s door.

  • And you want to blow all that lovely sump juice into your air with your airgun? Just think about it.




Illustrative excerpts putting this advice into context from the thriller novel Cast Doubt. The action takes place in the fictitious factory of Gauge Precision Engineering. Barry. A machine operator had developed industrial contact dermatitis. Philip Wheatley the Health and Safety Manager is expecting a visit by the HSE.



Chapter 2 – Coolant condition

Chapter 2 – Observation of mist

Chapter 8 – Control hierarchy

Chapter 9 – Airgun mist controls





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