Cutting oil infections

[David S Newman]

I went to my local engineering shop today to scrounge some offcuts of steel. I noticed that his machines were pumping pink coolant, I asked why he's not now using normal soluable oil and was told it was because they had to change it once a month in case of an infection which would need the machines to be decontaminated . I have used in my home workshop normal soluable oil for 40 years, confess to only putting it on with a brush but the few pints I mix probably last for 6 months and never had a problem. Was he having a joke with me? but he's got me thinking, sure you'll know. David

[Mark Hockett]

David,
It might be that the soluble oil can get bacteria contamination fairly easy, so they were probably using a synthetic cutting oil that resists bacteria growth.

[Tim The Grim]

Bacteria will grow in soluable oil / water solutions and can cause severe infections. I worked in a CNC shop where a guy got cut and wound up with blood poisoning. He was OK after a months long treatment process.
At that same shop, they filled a plastic 55 gal. drum with some used solution. The shop closed for a week in the summer and the AC was turned off.
When we came back there was a horrible smell as we opened the door. Bacteria growth had caused gas which burst the drum and messed up the storage area. It was like rotten brown cottage cheese in a 10 foot radius.
All that being said I have used small batches like you with a brush for decades. I think maybe the problem comes from high volume flow in CNC machines and all the air that mixes in helping the bacteria to breed.

[jdleach]

Microbial growth in coolant preparations has been a real problem since the invention of cutting oils. In the case of your "typical" water soluble coolant, a mixture of light hydraulic oils combined with emulsifiers that permit the addition of water to create a milky colored coolant, problems with bacterial and fungal growth has been pervasive. Especially in the summer months when humidity and temperatures are high, the solution has a great propensity to start stinking, and get slimy with fungal growth. The old timers referred to the odor as "the Monday morning stink". In times past, the coolant was generally not changed, but used anyway to remove the smell (the aeration of the coolant, along with the heat of cutting, tended to reduce the microbial populations).

When one considers that diesel fuel permits fungal growth, and that the typical black cutting oil has a percentage of both animal and plant oils combined with petroleum, it takes no stretch of the imagination to realize that cutting oils and fluids can be susceptible to the same ills. It also takes little imagination to assume that persons with sensitive skin, allergies, and other conditions, may develop some pretty nasty reactions to coolants thus contaminated. I have known persons who have contracted severe skin irritations from contact with contaminated coolant. In the most severe cases, these individuals have required hospitalization.

So, the guy was not pulling your leg. He no doubt was using some synthetic preparation that is resistant to microbial growth, and changed it frequently so as not to open hiimself up to lawsuit, or penalties from the state for promoting a hazardous work environment.

[Carld]

In the past I used water soluble oil in a valve grinder and it would start to stink after a while. I would change it out then. After about a year of doing that I just drained the 3 cup reservoir after each use because I may only use it one a month or two.

It smelled terrible.

[jdleach]

Regarding the aeration of the coolant, be aware that the most virulent of the bacteria that populates a solution, is of the anerobic type, which means that it thrives in the absence of oxygen. The agitation of the coolant through machine operation and pumping, injects air into the coolant, thus killing large numbers of the bugs. In the shops I have worked in, including my own, the stench of the coolant on Monday was usually gone by Tuesday morning, or sooner. Unfortunately it always returned the following Monday until the weather became cooler.

That is why in the other post, the steel drum burst over the preceeding week in hot weather. Sealed within the drum, and lacking any oxygen, the microbes went apey, with the attendant production of byproduct gases that finally burst the barrel.

[jdleach]

To continue with my last, one must consider that the sometimes, almost lethal, infections that can occur through contact with contaminated coolant, is due to the rather nasty nature of anerobic bacteria.

While I do not know which anerobes reside in your typical coolant, I am familiar with a few of their relatives: tetanus and botulus, both having a high mortality rate even with the best of modern medicine. And there are others that can be equally nasty.

SO you don't go ga-ga, and rid yourself of all soluble oils out of fear, be advised that in 30+ years of being splashed with rancid coolant, and witnessing others get the same treatment, I have never seen anyone croak, and only one who went to the hospital for a stay.

A better solution to the microbe/mold problem, is to either buy some of the anti-microbial products that you add to your coolant to prevent growth (there are several on the market, MSC offers a couple), or use the old-time remedy I have often employed: add about a cup of bleach to each five gallons of coolant. Kills the buggers dead.

[tattoomike68]

A glug of Pine sol works great, it also makes the machine easy to clean. It wont hurt a thing.

[Fasttrack]

Someone on here mentioned putting a UV light above a machine's coolant resevoir to kill microbial growth - thought that was an interesting idea...

I read an article about the spoilage of water-soluble oils that mentioned the number one cause was contamination of the coolant - i.e. sunflower seeds, tobacco juice, etc, etc. If you keep the coolant free of other contaminates, they will last a pretty long time with all the modern anti-microbial additives found in most water-soluble oils.

[interrupted_cut]

In a shop I worked in, we put cheap aquarium air pumps and an "air stone" in the coolant reservoirs to retard the growth of anerobic bacteria. We also used aquarium heaters to keep the reservoirs warmer in the winter to reduce the shift in machine accuracy with warm up in the morning. Both provided immediate benefits for a less than $50 per machine investment.

[Black_Moons]

yea air stones seem like a good idea, though I wonder what aerobic(?) bacteria take its place.

I kinda wondered myself while planing to get a bandsaw and/or add coolant to my mill/lathe, what kinda coolants can one use that won't spoil?

With my usage, its likey i'll use it maybe once a week at max, so cost really isent important, shelf (or rather, tank) life is whats important.

[Fasttrack]

yea air stones seem like a good idea, though I wonder what aerobic(?) bacteria take its place.

I kinda wondered myself while planing to get a bandsaw and/or add coolant to my mill/lathe, what kinda coolants can one use that won't spoil?

With my usage, its likey i'll use it maybe once a week at max, so cost really isent important, shelf (or rather, tank) life is whats important.

Synthetics won't spoil. Pop open your Enco catalogue and look in the cutting fluids section. There are many different oils/fluids for different applications. I'm still using up the last of the WS-11 that I purchased. It worked great for my little lathe (it is NOT a synthetic) but I want something heavier and more stable for my Pacemakers. They generally sit for long periods of time, so sump life could be an issue. I plan on using something like OakFlo DSS 800, a semi-synthetic coolant with EP additives. The trouble with synthetics (or so I hear) is that they attack paint faster than the traditional coolants...


If you really want some nice stuff, check out Castrol's Superedge 6759. It's a little too pricey for my budget though ...

[gnm109]

A glug of Pine sol works great, it also makes the machine easy to clean. It wont hurt a thing.

That's a good idea. I also use a shot of Lysol in the coolant in my TIG welding recirculator. It keeps things nice in there. When I first got it, I was using soulble oil and water as coolant and it was growing clumps of bacteria.

Now I use distilled water, Miller coolant mix and lysol and there are no more bugs.

[wierdscience]

I'm still using this stuff,some of it the same batch as the last time we all talked coolant and bacteria and it still hasn't gone sour.

http://www.synlube-mi.com/Templates/Products/soluble_oils/coolant_king.htm

[Boucher]

Not all things work together.

Pine sol and Lysol are good products but there are things that they are not compatable with. I can't remember the details but be carefull mixing things that were not meant to work together. Of course if you look at the bleach bottle it has a skull and crossbones on it. In proper application rates it is probably the safest choice. I think that it is Pine Sol that a lot of people are allergic to.