CNC coolant and water-soluble cutting fluid, stocked in Canada. Semi-synthetic, fully synthetic and vegetable-based, in pails, drums and totes. Prices and stock on every product page, order without asking for a quote.
What you buy is concentrate. What runs in the machine is the mix. A 5-gallon pail makes roughly 60 gallons of working fluid at 8%, so the number on the invoice is not the number that matters — concentration is.
Each product page lists its refractometer factor, the material groups it suits and whether it holds up under high-pressure coolant. Those three answer most of the choice.
CNC coolant — also called cutting coolant, cutting fluid or soluble oil — is a concentrate mixed with water and run through the machine to cool the cut, lubricate the contact between tool and workpiece, and flush chips out of the way. Shops use all four words, and in a CNC machine they almost always mean the same thing: a water-soluble fluid, not a neat oil.
This category covers water-soluble products only — what catalogues variously list as water soluble cutting oils, soluble cutting oils or plain soluble oil. If the job needs undiluted oil instead — threading, broaching, deep-hole work — that is cutting oils.
You are buying concentrate, not coolant
This is the part that changes how the price looks.
Nothing in this category goes into the machine as supplied. It is concentrate, and it gets diluted. At a typical 8% mix, a 5-gallon pail makes about 60 gallons of working fluid; a 55-gallon drum makes close to 700. Run the same pail at 6% and it stretches to 80 gallons, at 10% it drops to 50.
Two things follow. First, comparing pail prices between products tells you very little until you know the concentration each one runs at. Second, the cost of a sump is set by the mix you hold, not by what you paid at the counter — which is why concentration drift is expensive in both directions.
The coolant calculator works out what to add for a new fill or a top-up. Sizes here are 5-gallon pails, 55-gallon drums and 270-gallon totes.
Reading the sump: the refractometer factor
A refractometer does not read concentration. It reads Brix, and you multiply.
Every coolant has a refractometer factor — ours run between 1.2 and 1.6, and it is listed on each product page. Actual concentration is the reading multiplied by that factor. A reading of 4.0 on a fluid with a factor of 1.5 is 6% in the sump. The same 4.0 on a factor of 1.2 is 4.8% — weak enough to start losing lubricity and grow bacteria.
Which is where shops get caught. The refractometer target gets written on a card taped to the machine years ago, the shop later switches to a different coolant, and nobody changes the card. The reading looks right and the sump is running one or two points off. If you change product, change the target number with it.
The filter panel on this page lets you sort by refractometer factor, which is worth using if you would rather keep a mixed shop reading against one number.
Choosing the best coolant for CNC machines
The practical difference between formulations is how much mineral oil is in the concentrate, which is listed on every product page.
Semi-synthetic
Mineral oil at roughly 20-30%, blended with synthetic additives. The general answer for a shop that cuts several materials and does not want to run two sumps. Enough lubricity for steel, clean enough to keep the machine tidy. EASYCUT UNI301 is our most-ordered coolant and is the one to take if you would rather not think about it.
Fully synthetic
No mineral oil at all. Cools harder, foams less, stays clear so you can see the cut, and tends to hold a long sump life. It gives up lubricity in return, so it suits grinding and high-speed work more than heavy cuts. The carbide grinding coolant is a synthetic for exactly this reason — grinding tungsten carbide needs a chemistry that will not leach the cobalt binder out of the surface.
Vegetable and ester-based
Lubricity closer to an oil with the handling of a water mix, and a biodegradable base. Worth looking at for gummy material, for shops with a disposal or workplace-exposure reason to move away from mineral oil, or where operators have skin trouble with the current mix.
Material-specific
Aluminum is the usual reason to buy a dedicated fluid — the wrong chemistry stains it, and a mix aimed at steel will not always keep the finish. Cutting fluid for steel and cutting fluid for stainless steel are less often a separate purchase: most semi-synthetics cover both, and the product page tells you which ISO material groups it is rated for — P steel, M stainless, K cast iron, S high-temp alloys, H hardened.
High-pressure coolant is a separate question
If you run through-spindle coolant above 40 bar, foam becomes the deciding factor rather than lubricity.
High pressure whips air into the fluid. A coolant that behaves perfectly in a flood system can foam over the top of the tank on a high-pressure pump, and once the sump is full of air the pump loses prime and the fluid stops arriving where it matters. Product pages state whether the coolant is suited to high pressure, limited, or not — check that field before ordering if your machine has the option, because it is not something you can correct with concentration afterwards.
Keeping a sump alive
Coolant does not usually fail. Sumps do.
The three things that decide how long a fill lasts are concentration, tramp oil and water quality — covered across our coolant articles, in particular mixing and water quality and the right way to top up. Topping up with plain water is the single most common way a good coolant ends up blamed for a bad sump.
When a sump does have to come out, cleaning the system before refilling is what stops the new fill inheriting the old one's bacteria. That is what the alkaline system cleaner in this category is for — it is not a coolant, it runs through the machine between fills. Skimmers and refractometers are in oil skimmers and fluid management equipment.
Buying coolant from CNCmarket
We supply coolant in Canada under our own EASYCUT brand. Prices and stock are on every product page and you can order online without waiting for a quote. Delivery is free across Alberta and we ship anywhere in Canada.
We also run our own machine shop in Calgary and these are the fluids in our own machines. If you are switching products, tell us what you run now, what you cut and what your water is like — the answer is usually one product, and occasionally it is that you should stay where you are.
