So we upgraded to a 60 watt laser and word got around that we have it. Been cutting a lot of thin wood for various customers.
Top of the sheet, the laser head has an air-assist. When the beam fires the wood ignites briefly and the air-jet extinguishes it. There is a char-spot where the beam burns through and of course the edges of the cut are singed as well. The air-jet prevents fires and blows out flare-ups... in certain situations though the wood can ignite and you end up with an air-jet fueled fire.
Seems to me better results could be had if I use a stream of Co2 instead of air. The laser has a huge exhaust fan so we'd be pulling the CO2 out of the work area and our workshop has an always-open (even in the winter) window-and-fan because of the fumes we generate doing other stuff. I'm thinking CO2 would prevent even that brief flare/burn at burn-through and it would work better at keeping flare-ups under control. Given that we are effectively directing cool CO2 gas at the burn point we've displaced oxygen and kept the work surface cool at the same time.
Aside from the hazard of overwhelming one's self with CO2 and ending up dead and on the news, am I thinking right here? It seems it would work, there are some safety challenges (interlocks?) that I would have to work through but if it's technically sound I might look into it further.
However, a couple things to keep in mind: First, you'll use up a LOT of gas. Depending on how much you cut and what kind of flow rate you set, I could see even a 50-lb tank only lasting a few days, or maybe only as much as a week.
Locally, CO2 is almost $2 a pound, so that's $100 in gas a week, assuming my rough seat-of-my-pants guess is close.
Then of course there's the hassle of having to keep swapping tanks, the requirement you have at least two on hand (one in use, one full backup, which often works out to being three on hand- one in use, one full backup, and an empty waiting to be exchanged) and having to keep moving around heavy tanks.
Second, also depending on flow rates, you can fairly easily "freeze" even a big tank. Sustained draw from the tank can cool it rapidly, potentially even to the point of freezing it solid- meaning little or no tank pressure, meaning little or no blast at the cutting point.
Neither of those things are unworkable, of course, or fatal to your idea. But should be kept in mind.
You can give it a try with a cheap 20-pounder (know anyone with a Kegerator?

A 20-pounder will also give you a better idea if you're going to get "freezing" issues- the smaller tank will freeze up a lot faster than the 50 or 100-pounders. If you don't have a significant problem with the 20, a 50 will work just fine.
And, as added protection, throw an inexpensive CO detector in the cutting room, down low. I'm pretty sure they also detect CO2, and should give you a warning if there's a leak or excess buildup.
Doc.