Burnt odor on finished product

Hello, I’ve finally got my laser up and running and made first pieces. It’s Sculpfun S9 5.5W diode laser and i run it with air assist in a Creality laser engraving enclosure that is vented outside the window (don’t tell my neighbors).

Everything is fine and smoke is being pushed out nicely, i always wait a bit after the job to let the air inside enclosure change so there’s no smoke directly, but the wood and pieces smell a lot still.

Whole room is smelly after i leave the parts there for a bit, is this normal? How can i reduce it? I’ve read about ozone generators, do they really work for this?

Also worth mentioning I’m cutting 3mm birch plywood at 200mm/m and 85% amd 2 passes, cut’s through just fine apart from a few places here and there that i just finish with a knife. Maybe if i go faster and multiple times it would burn the edges less? I don’t get any burn or smoke marks on either side of the wood. Or maybe sealing it with something or washing the pieces would help as other comments suggested online?

What has worked best for you? I would very much like to get rid of the smell as much as possible. Thanks!

You are burning wood.
Yes, the smell is going to be in the wood for a while. Hours, days depending on a lot of factors like thickness and engraving.

You must be in the city, us country folk love the smell of a camp fire or wood burning fireplace.

You could always take the finished piece outside and let the smell go away, but it could be a while.

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Ultimately reducing the odor comes down to either cleaning the materials after the fact, using wood with laser-safe glues (this is a BIG one), or having incredible air blast and exhaust (typical of big CO2 lasers)

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I don’t really mind the smell, but i wouldn’t like to sell the pieces while they smell this much. Would wiping down the burned edges help? I’ll try to air them out, but in a flat it’s difficult to leave them outside while protecting them from weather. If the smell won’t go away on it’s own and after cleaning, I’ll probably try the ozone generator, that should work 100%. The smell and smoke while cutting it isn’t a big deal it vents outside alright, only after i take the pieces out they give out bad smell that fills the room and i wouldn’t want it to stay in furniture and stuff like when you smoke inside and you won’t ever get rid of the odor.

If you have good venting, you could try to give them a brush off inside the enclosure with a semi stiff paint brush. It’s just what is left on the wood that has that smell to it. (mostly)

Spray fabreze in to the enclosure? No, probably a bad idea.

Make sure your optimum focus is not focused on the surface of the wood you are cutting, rather aim for the middle of the cut depth as the best focus.

IOW, if you are cutting a 3mm wood, focus 1.5 mm closer to the wood than you will on a surface engraving. Out of focus by +/- 1.5mm will be less smoke and smell than out of focus by 3mm.

Another thing would be faster moves and more passes. Just because the machine can grind through it in two slow passes, does not mean that is the best setting. I would rather go 6 passes and less power.

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As Colin said, a huge venting fan would help. Even if you do not smell smoke, if there is smoke in the enclosure, the wood could absorb some of that. You could try wiping it down with rubbing alcohol, although that would be more for surface areas and ‘yellowing’. Probably the best bet is to seal it with a polyurethane or similar. Something that has a non porous surface as opposed to mineral oil or similar.

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Just some additional notes:

Make sure the air assist pump is OUTSIDE the enclosure. Otherwise, the pump and the lenses will die soon.

Definitely. I usually never cut below 600 mm/min. In fact, it’s even faster to use higher speed and more passes (description here: Settings guide - Diode Laser Wiki)

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Thanks for info! I do have the pump outside if enclosure. I’ll try to lower the focus point a tiny bit and go faster, now it was 200mm/min at 85%and 2 passes so i will try 600mm/min at 85% and 6 passes, so it’s proportionally adjusted and we will see.

Actually, I guess you might get away with 600/85 and 5 passes. That’s because the faster you go, the less charring appears that the laser has to cut through on the next run. Therefore, it’s usually even faster. But just test.
Some example for reference.

So i’ve tried some settings, on 200(85/2 it cuts nicely and the edge is fairly black, on 600/85/5 it actually didn’t cut through entirely so i’ve tried 600/85/6 as well and it cut just like the first option, just the edge was a bit less black, but i dont think there’s any difference in the smell of the edges. So i guess my go to would be 600/85/6 for cutting 3mm, or should i try to go even faster and add more passes?

I think that’s fine. As usual: choose that setting that you like most :slight_smile:

You might try solid wood rather than plywood. Some of the odor may come from the burning glue in the plywood. Another idea might be to sand the burnt edges until the black is gone (and perhaps the flat sides lightly) and coat the pieces with some sort of clear lacquer or the like.


There is always the option of using a masking agent.

I used a LASERDARK.COM product, huge rolls of light masking tape that works great. All the smoke and mess sticks to the masking tape and it peels off really easily when you are ready. My 10w laser hardly notices the extra thickness while engraving or cutting wood/

I acquired my first diode laser (NEJE A4 E80 20W) at the beginning of January, and after a just few engraving I knew that I need an enclosure with an exhaust system even if it is located in my wood workshop under my garage. After trying the enclosure with the exhaust it was still smelly in my shop and since I am in Canada (working with -15C outside), I was replacing the room air with outside cold air. So this week I added an input air vent from outside to the enclosure, this is much much better and less colder in the room. Here is a picture of my installation. I am sharing my spry paint shop corner with the laser which I can move easily when required.

Also I rapidly noticed the smell from the 3 mm plywood parts that I was cutting. A simple solution which works perfectly is to put a coat of shellac, it is paint on very easily and dry very fast.

Just a side note: make sure the laser does not operate far below 15°C. Otherwise, the heat of the beam can cause the optics to crack and humidity might get a problem. Though it’s good to have a cool environment, the diode also should not exceed 30°C.


thanks for your comment, I must say I didn’t thought about that. If it is too cold, I could mixe the outside air with some inside air by opening my inside vent trap. The air assist pump which is not in the enclosure send room temperature air into the laser near the optics which may also help. I have done some cuttings since this modification and every thing seems ok when I do the cleaning.

I’d say those are also just general recommendations. I guess, you will find many people who operate their lasers in very different conditions. Maybe in some cases lifetime is reduced, but the question is whether anyone will notice. E.g., if lifetime is decreased from 10,000 to 7,000 hours, one has to reach those 7,000 hours first. I do not guess many hobby lasers operate that long before being replaced by the next generation :slight_smile:

Speaking of smell, I’ve also noticed that the lingering smell in my room is mostly from the honeycomb and the aluminum tray under my laser. That honeycomb smells like camp fire all the time. I try to clean it, although it’s not easy. I’m thinking of switching to a steel grill (from a bbq) instead.

The honeycomb does not allow air to flow freely - so it will collect dust and ash. You could try to put a small coin under each corner to lift it off the honeycomb slightly off the surface. It will help, but it will not totally overcome the airflow issue.