If GF's laser cut caused the material 'on fire' inside of machine?

Hello all GF lovers

To this topic question that I hope to make it clear and would like to listen to all GF lovers’ most practical and correct advice. I wonder if GF caused the materials :fire_engine: on fire :rotating_light: inside of machine, what would I deal with that accident? :ambulance: I am thinking that maybe for many GF lovers, we are not the laser-cutting experts, so I probably will prepare something ‘just in case’ if the machine or material is on fire from the working bed. OR perhaps GF staffs could share with us standard operating procedure if people encounter this kind of situation.

Any comments? Many thanks.

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I plan to keep a Co2 extinguisher close by. Just in case.


This thread has some info on various fire extinguisher types and where to buy them:



I’m pretty sure many laser owners have had a “flame” on the substrate. Besides the safety issue of having an extinguisher nearby (see the various forum topics mentioning this), the best prevention is never leaving the machine unattended. Air assist greatly reduces the risk (which the GF has) , but I’ve had foam and paper catch on fire before I got my assist on the K40. Because I was watching, I was able to take the piece out and get it to a sink w/o any issues (apart from the smell…). May want a metal trash can nearby for small fire if it were to happen, but I think the GF will be for the most part unlikely to cause fire unless you are using questionable materials (even if “safe” like some foams and paper/cardboard). But again, typically if they catch on fire, as long as you are watching you can put it out relatively easily by “hand”. :hotsprings:
I would hazard to guess you’re more likely to have a fire from your toaster or toaster oven than the GF.


The other extinguisher that was talked about is the Halotron, Amazon has them, I purchased one of these and have it waiting on the Glowforge, here is the link https://www.amazon.com/gp/product/B009WUGRXS/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1


I have a pattern that reliably sets cardboard on fire. Tomorrow I will try to remember to record some cardboard tests to show you what a laser fire is like.

If anyone has ever built a fire and stoked/primed with cardboard, they should understand that cardboard loves to go up, and it does so fast and hot. So I cannot imagine many materials you will put in your laser which will be more of a fire risk than cardboard. Absolutely everything else will be a slower build.

Catastrophic laser fires are (IMO) 100% due to not staying nearby and watching the machine. Those users walked away, and allowed a fire to sit for a long time. The #1 safety mechanism is you sitting there and paying attention to the cut, as I can hopefully demonstrate if I remember to take a video tomorrow.


From all of the “flair ups” I have seen in many laser videos across the last year, I haven’t seen one that I couldn’t snuff with my thumb, but my hands are used to abuse.
If I was working a material that tended to flair, I would just keep a damp rag within reach.

That being said, I grind, weld and plasma cut so I keep 2 ABC extinguishers in the shop.
Those are messy as opposed to a halon extinguisher, but the extinguishers are a fail safe for me. If I needed their capability, the mess they make is the least of my problems, and a small price to pay.


Get a CO2 or Halon extinguisher.

Spraying a standard ABC extinguisher inside the Glowforge will get the extinguishing agent on the processor board, and WILL fry it. Then you have a small mess to clean up, and a new Glowforge to purchase.

A bit of a larger price to pay.


That is good thinking. I’d hate to discharge a Co2 or Halon extinguisher for a small flair that could easily be handled with a damp cloth.


Wonder why an ABC would fry it? The C is designated for electrical fires, so it shouldn’t be conductive. I’m not aware of any corrosive effects of the dry chemical agent.


Yup, I learned 40 years ago on submarines that if it is electronic and you want to use it again inert gas is the only thing to hit it with. Now electrical, not electronic, you might be able to clean up and get working again.


Most circuitboards are coated with a thin layer of protective sealant to help prevent the usual issues ICs have with static discharge. But the extinguisher can pretty easily blow through that layer.

The agent in the air will also bring in far more than typical levels of static charge.

Many extinguishers use monoammonium phosphate (typically what covers the A portion of ABC), which is corrosive to metal when allowed to hydrolyze (becoming phosphoric acid). And circuitboards have many areas where there is precious little more metal than absolutely needed.

The extinguishing agent can also be conductive, making the static electricity the least of your concerns, as you are now shorting components directly to one another.

Much of the damage is potential, not guaranteed. And loads of it is long term, if you failed to clean up every single spec of agent afterward (which you won’t, since the agent is essentially molten during use, and can get into any tiny crack)


Thank you for the detailed explanation. I can see where subsequently getting the agent wet would be bad.

There is no way a flair is going to get away from me to the point I would ever need to use the extinguishers. I have raised hell in there for 20 years in the form of torch flames, grinder sparks, molten metal and haven’t needed them yet.
This laser will be the single most expensive tool I own, and fire is not it’s fate!

Smothering is the quickest way I have found to extinguish a fire. I once threw a blanket over a motorcycle completely engulfed - I could hear the gasoline boiling. Poof, it’s out.
(No, it wasn’t my bike, or my living room. A friend rebuilt it in his apartment living room during the winter and tried to start it.)


I would humbly request, if you can even find an extinguisher that uses it, to please avoid halon. The substance is an extraordinarily efficient ozone destroyer, and has been pretty much banned.

As for CO2, if you’re going to use it, please get training. The blast issued forth from a CO2 extinguisher, if improperly used, is likely spread embers all over the place an create a larger problem than you started with. Imagine expending your one extinguisher on a fire, only to have four more light off from smoldering embers a few minutes later. Also, if you’ve never used a CO2 extinguisher (also with many other dry powder extinguishers, but especially CO2), you’ll be particularly surprised by the static discharge created when you discharge it. It’s important to keep the canister on the ground when you discharge it, to give some of that static a place to go. Otherwise, you’ll feel quite a bit like Luke Skywalker looked during his run-in with Emperor Palpatine at the end of Episode VI. --it won’t kill you, but you’ll definitely not need that kind of surprise when you’re already dealing with a fire.

I’m going to go out on a limb here and just suggest a box of baking soda be kept nearby. For a small fire discovered in the small’ish enclosure of your new GF, you’re not going to want anything propelled under high pressure. (Fire extinguishers have all of that force to allow you to go after a fire from a safe distance of several feet.) If something catches alight inside your GF and you’re not comfortable simply reaching in to put it out with your hand, you can safely smother a fire with baking soda. Baking soda works through two effects: first, you can smother a small fire with a pile of baking soda; and second, the heat of any remaining embers actually cause the baking soda to break down and (gently) release carbon dioxide, further smothering the fire by displacing local oxygen. It’s really wonderful stuff. You can simply vacuum up any remaining (after you’ve allowed the pile to fully cool. There’s no need to turn your vacuum cleaner into a home afterburner demo). It’s non-toxic, as are it’s breakdown components. (Commonly used in cookies! yum!)

All of this discussion, of course, goes with the assumption that you were present either at the moment of the fire’s ignition, or very soon afterwards. This requires always babysitting your GF when it’s operating. If something catches fire inside an unattended laser cutter, eventually leading to the whole thing being on fire, then you’ve got a combination electrical fire, burning plastics fire, and heaven knows what else. That’s where you’ll want your large ABC extinguisher and a call to the local fire dept. At that point, the laser cutter is likely to be a total loss and you’re just trying to protect the surrounding building/business/domicile/workshop/etc.

Being a bit of a high school pyro, as well as fire fighting training in the Navy and prior to wintering in Antarctica, I’ve got a healthy respect for fire, and a (perhaps at times annoying if you ask my wife) paranoia about things unexpectedly catching fire. Enjoy life! --but try to enjoy it without being on fire. :wink:


This sounds like a good logical intermediate step between a damp cloth and the nuclear option of Co2. I think I’ll keep all three. Can’t have too many options.


I definitely like the damp cloth idea! That’s probably the best idea yet.

My only doubt is the likelihood that I’d forget to dampen it before cutting, whereas the baking soda never dries out.


Humm, good point. I’ll have to work out a long term storage for a damp cloth. Perhaps a small ziplock full of water that you can smash the cloth around?

And yeah, I’m paranoid about fire as well. It was 40 years ago but life on a submarine will make you respect even small fires.


I think this is a great idea. I plan to figure out having both a wet rag and a container of baking soda on hand. My tiny little laser studio is but steps away from my kitchen anyway, so this should be a simple resolution to making sure…just in case of fire.

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I’m going to hold off answering and defer to the manual that will come with your Glowforge, which is receiving an immense amount of effort and attention to be sure it’s safe, comprehensible, and comprehensive.


Just to point out for people… Halotron are not Halon fire extinguishers. Halotron came out in the early 90s as a replacement for ozone depleting Halon.