Soluble cutting oil just floating on water

I bought a mill second hand last summer, and with it came a nearly full gallon bottle of chronos multi-cut G soluble cutting oil. I've just tried mixing some up at the recommended 25:1 ratio, adding the oil to the bottle of water as instructed and it just floats to the top after mixing.

It did sit in a non-insulated garage over the winter, despite the label warning "protect from frost". Will freezing have messed up the emulsion? If so is it still usable neat rather than just chucking the whole lot away?

when adding oil to water stir water vigorously adding oil VERY slowly.

Could be motor oil pored in a random container. never know with second hand stuff.

If it does not walk like a duck its probably not.

What does it smell like? normally very different to motor oil.

Soluble oils are not really soluble, they just have an added surfactant. This helps the process of the oil breaking into small droplets and reduces water surface tension to keep the small droplets in suspension and so form an emulsion. It is possible the surfactant had been damaged by frost but I don't know. All the soluble oils I have used I just put the correct volume into a hand sprayer then added the water (rain water from a water butt to avoid any hard water salts) followed by a quick shake, with the top on, to mix the two.

I would just assume it is no good and replace it with something you know is really a cutting oil that has not been frost damaged, it goes a long way when diluted down with water so the cost is not too bad.

Martin C

Hi, like Martin, all the soluble cutting oils I've ever used in my day jobs, are put into a container and then the water was added, and in the machines that I've used, you would put about 500 ml of soluble oil it a standard size bucket, and then fill the bucket with water under a tap or with a hose, which would mix it to a milky looking solution. Sometimes though, if the barrel of soluble oil had been open for a good while, you would get some streaking on the top, where not all of the oil would mix.

Regards Nick.

Nothing to be lost by adding a squeeze of washing up liquid

The usual reason given for not recommending using washing up liquid for car washing or windscreen washer fluid is that it contains salt. Probably not a good idea to use it on machines if it does. The reason I use rain water is to avoid hard water salts so I would never put washing up liquid, even if very dilute, on my machines without being sure it was salt free.

Martin C

You only want a couple of drips of washing up liquid to a bucket full of water, it’s a p*** in the ocean amount, the couple of gallons of water will do more harm to your machine.

Use car shampoo then

Electrolytic corrosion requires an electrolyte. Water with salt in it can act as an electrolyte, salt free water is a very poor electrolyte and salt absorbs atmospheric moisture as well. Not a good idea to have even a very small amount of salt water on ferrous metals. If the majority of water evaporates the salt is left behind. I have seen problems with steel and stainless steel corroding because a hot water bath used to clean off dye penetrant products and flash dry the part was filled with tap water instead of demineralised water.

Martin C

I took out a second mortgage to buy 25ltr of Q8 sol oil years ago….no idea on current prices…

It's almost gone now…..

during that time I bought a deep stored MYFORD S7 and VMF mill ? also by MYFORD…..

both are as new with delivery /storage wax on them…..

So no way am I gonna let sol oil near them…..

I'll be using Hydraulic 46 oil from now on as coolant…..both the above and my Bridgeport and Student machines will get the 46…

Apart from that my tractor uses it as well….so always in stock….

the odd gall of sol oil left will only be used in the metal cutting bandsaw as it's so messy…..

+1 No need for Beardy Mike to take a risk though because the risk is easily tested.

Take two shiny nails. Half submerge one in a jar of clean water, and the other in a jar of suspicious suds made with a dash of detergent. Compare how quickly the nails go rusty. If the suds are good, the nail should rust much more slowly than the one in plain water.

Expect quick rusting if the detergent contains an Anionic Surfactant - most Washing-up liquids do. I like John Haines suggestion though - unlikely that Car Shampoo has anything in it that encourages rust.

Might be easier just to buy new and protect from frost. However, whether a cheapskate remedy works or not is always entertaining. There should a Model Engineering Award for the most audacious use of an unknown potion in the workshop. Special category for traditional methods known to be dangerous because these are widely believed to work better than any modern preparation. Volunteers needed: Red Lead makes an excellent cutting paste! Double points scored if the operator chain-smokes Capstan Full Strength whilst machining.

I believe Science doesn't understand how surfactants work - anyone know? For example, seems unlikely that a smear of WD40 would make any difference when cutting Aluminium, and yet it does - a big difference. Thought to be something to do with the electronic bonding between atoms that occurs at surfaces, causing hardening at the boundary. How much depends on the materials in contact. HSS biting deep into Aluminium has no effect on surface hardening, but a drop of surfactant weakens it considerably. Then HSS cuts better.

Whatever causes boundary hardening gets stronger the more a surface is polished. That suggests to me it's related to the powerful force that sticks wrung Gauge Blocks together, another scientific mystery.

Dave

Chances are that what you have is just engine oil.

Soluble oil usually just mixes without any problem, and it,s not dear anyway.

I would just dump whatever you have and buy a gallon of proper oil, which at 20 to 1 should last you a long time.

as others have said its unlikely to be what it says on the tin. could be previous owner used it as neat cutting oil, got decanted into any available container to get it home

Thanks for all the suggestions folks, I got some time this afternoon to try a few things. I eventually tried something I probably should have started with - vigorously shaking the gallon bottle of oil. After that it immediately mixed with water to give the milky liquid I'd been hoping for all along. A thin layer of oil is floating up, which I guess is one particular component that is no longer emulsified - previously I must have just been pouring this off the top into my water mix.

My conclusion is that this probably is what the label says, although seemingly somewhat degraded by time settling and/or freezing.