What is the Coolant (OEM) mixture

Hi Guys

So just last week when I was about to use my GF I noticed a big puddle of liquid on my floor in the garage. After inspecting the puddle i determined it was coolant.

I was able to open up the left part of the GF to expose the Coolant Reservoir and the hoses and noticed that one of the hoses had come off and that the Coolant Reservoir was empty.

I am confident that over time that the hose has expanded and slid off the spot it was suppose to be on and i think i can put it back on and tighten it with either a clamp or zip tie.

The issue is that i don’t which coolant or mixture to use. It states OEM but can’t find anywhere to purchase that online or even in this support group.

I have contacted GF support and they havent been able to help except for say to send $1000 and the glowforge back and they will fix it. The issue is that I live in Toronto, Ontario Canada so shipping it back is not really an option due to customs of sending it over the border.

Any suggestions or any one the mixture example: (50% distilled water and 50% Coolant) etc

Thanks in Advance

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DM a user named “Deleted”. He might be able to help you.


Done. And thank you so much

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Also, if you are on Facebook, Jonathan is in the Glowforge Users Group under his own name, Jonathan Gleich.


A glycol-water mix. Probably just to keep water from freezing when units are shipped in winter. You’d probably be fine just using distilled water. Other lasers with glass tubes don’t use anything special.


I would hope it’s actually something like Mineral Oil, like what runs inside the processor cooler on my PC workstation. Water cooling systems in proximity to electrical circuitry is never a good idea. No system is 100% failure proof. And it’s not like there haven’t been cases of GF cooling systems leaking. Mineral Oil doesn’t conduct electricity.

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One person seems to think it’s mineral oil. I can’t see that, it would separate when not circulating.

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That’s what Jonathan said before he deleted everything and ran away. A 50/50 mix as I recall.


I should be ok if it’s Propylene Glycol and water mixture right?

That’s what Jonathan filled his with. I believe at least 2 other people here have done the same within the past few months too. The last one was similar to your issue but their hose sprung a small leak so they were able to catch it before it emptied. Tying your hoses off with small zip ties is a good idea.

Back when I had a remote coolant laser, that’s what I used - no issues even after years of use. I’m not sure why GF tries to make it some deep dark secret like it’s unicorn tears or something. It’s disingenuous and frankly a bit short-sighted of them. It does nothing for their brand.


I have used the mixture (50 % Glycol and 50% Distilled Water)

It went through the laser tube and the laser head moved around

Now the Orange Light is solid and on

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Side note: lots of small bubbles are in the laser tube

Check your hoses to see if they’re not leaking. A small leak might allow air in. Otherwise the bubbles should clear themselves if the system is otherwise leakfree. I’d leave it overnight to see if the bubbles dissipate.

Now we didn’t fill it right to the top because in cars you aren’t suppose to

Should I be filling it to the top?

Sorry for all the stupid questions but you don’t understand how much I appreciate the help

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Hoses do not appear to be leaking

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Tried doing a test run with just a Letter and it cut through and worked


Thank you so much for all the help everyone

This community is the best


If anyone wants to contact Jonathan Gleich or needs tech support he can be reached here: Friendliest Glowforge Group on Facebook | Facebook

3/4 full is fine now that the laser tube has filled. The extra space in the reservoir will absorb any expansion as the coolant heats up.

No, mineral oil won’t separate. It’s a refined petroleum distillate, there’s nothing to separate out, it’s all the same stuff. Glycol and Water are more likely to separate if not stirred, since they have very different molecular weights.

Mineral Oil is what pretty much every PC processor liquid cooler uses. It’s preferable to Glycol and Water because it’s not conductive. If it leaks inside your PC, it just gets things oily.

My GF’s cooling system has never leaked, so I don’t know what’s in it. But given the relatively low “high temps” at which the GF operates (no where near the boiling temp of Water), the only reason for Glycol and Water is as an antifreeze, which I suppose is important for shipping it. But that’d be the only reason I could think of. If there’s no risk of freezing or boiling, Water alone will do a better job of removing heat. So if you have to replace the coolant in your system and you don’t want to use Mineral Oil, my recommendation would be to just use plain distilled water. It’s no more or less conductive than a mix would be, it’ll do a little better job removing heat, so there’s no added risk, and it’d be less messy.


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