Metalworking fluid is the problem, and it is a different problem from plain dirt. Coolant is designed to emulsify oil so it can carry heat and swarf away. Your hands are in it all day, and it emulsifies your skin's oil just as happily.
Why coolant is harder on hands than grease
Water-soluble cutting fluid contains surfactants, whose whole job is letting oil and water mix. That is exactly the mechanism that strips the lipid holding your outer skin layer together. Add the alkalinity that keeps the fluid from going rancid, plus fine metal particles acting as an abrasive, and you get skin that dries, roughens and then splits at the knuckles.
Worth saying plainly: persistent rash, itching or bumps from coolant exposure is occupational dermatitis, it is common in machining, and it belongs with a clinician rather than a tin of balm. What is below is for ordinary dryness and cracking.
What helps
- Barrier cream before the shift, not just balm after it. Anything that reduces contact beats anything that repairs after contact.
- Rinse and dry properly at breaks rather than wiping on a rag. Fluid left sitting on skin keeps working on it.
- Heavy balm at night. The eight-hour stretch is the one that rebuilds.
- Nitrile for setup and cleanout, where exposure is heaviest.
Why tallow rather than a lotion
Beef tallow is built from largely the same fatty acids your own skin produces, so it absorbs and becomes part of the barrier instead of sitting on top of it as a film. Beeswax keeps it there through a hand wash. Most pump lotion is mostly water, which is why it feels good for twenty minutes and is gone by the next break.
How to use it on a working hand
- Heavy before bed. The application that actually repairs. Eight uninterrupted hours beats six rushed ones. Cotton gloves over the top if the splits are bad.
- On damp hands after washing, so there is water in the skin to hold onto.
- Knuckles and finger webs first. That is where splits start.
- Not right before gloves. Give it ten minutes to absorb.
Unscented, if you would rather
Plenty of people do not want a fragrance on their hands at work. Raw is the same seven-ingredient base with none in it.
Why a tin
A screw-top tin lives in a toolbox, a bag or a door pocket without leaking, which a tube will not. A 2oz tin lasts most people six to ten weeks at nightly use.
Made by hand in small batches in Wakarusa, Indiana. Seven ingredients, and 5% of every sale goes to FreedomSystem, which connects veterans through authentic camaraderie and meaningful programs.
