Laser on wood and cork: how to cleanup burnt residue?

Hi guys,
I’m trying to use the laser in the wood and/or cork and it seems a good result but if I touch the parts after the work the pictures become dirt. I suppose the burn process leaves some residue but… how to laser engraving a picure in the wood so that it not get dirty when touched?

@AirMonk if you are saying that material is transferring to your finger when touched, that is normal. If you are talking about the residue that settles on surfaces, that it because you are not exhausting the fumes. The fumes from lasering are EXTREMELY DANGEROUS when breathed in. They either need to be exhausted outside, or they need to be filtered. When exhausted, there should be very little to no settling of residue on any surfaces. The standard Enclosure has a fan that is strong enough to exhaust the fumes.

@WilliamBosacker where does the standard enclosure exhaust to? (assuming I’m never going to pay $500 for an air filter) You’re scaring me with the all caps bold text, and now I’m having to rethink my ideas about how I’m going to set up my DIY enclosure for laser readiness…

The standard enclosure ships with a length of duct hose that fits over the exhaust fan opening. I ended up building a semi-permanent window installation for the other end, so that the enclosure vents outside.

@nivekmai You are right to be concerned. Lasers create extremely toxic fumes when used on any material that I’ve ever seen. I’m planning to buy the air filter and enclosure even though it’s expensive. It’s technically possible to build your own rig for that, but you won’t have the benefit of knowing the status of the filter such as when it needs to be changed. Here’s a DIY filter that I saw…


Thanks guys for all the responses!

I think the danger is being way overstated.
It’s depends a lot on the materials you’re using.
There is a definite range from pvc/vinyl, which should never be cut, to natural materials such as wood and cotton that could be irritants. Everything in between has different levels and types of compounds that is created.
The SM laser isn’t that powerful and the amount of byproduct it inherently creates isn’t that great.
If you bbq or burn wood in a fireplace you’re creating and ingesting a lot more carcinogenic compounds.

Much more danger from dihydrogen monoxide:

Sorry that we’re not really answering your question, @AirMonk. The Department of Bleeding Obvious Suggestions recommends experimenting with vaccuum cleaners, damp sponges, tape, and other things capable of lifting particulate residue straight up without smearing. Or you could try carefully applying a clear spray sealant, if you’re done with the piece.

I realize that this isn’t answering the OPs question, but I feel it necessary to respond to avoid misinformation.

I disagree with your statement that even wood is safe to cut with a laser without proper ventilation. See

Unless you know for certain that the material you are etching/cutting is free from contaminants, even wood or MDF release unsafe chemicals. That’s because most wood products are just that, products. They aren’t just wood wood. There are glues and other binders as well as chemicals used to treat the wood that can and will be released into the air with a laser.

The typical firewood comes from a tree, dried, and without treatment. So, the issue of fire in a fireplace is not analogous.

Here are the chemicals cited by the Carnegie Mellon information:

Benzene: Benzene | C6H6 - PubChem - Not safe - “Exposure to this substance causes neurological symptoms and affects the bone marrow causing aplastic anemia, excessive bleeding and damage to the immune system.”

Formaldehyde: Formaldehyde | H2CO - PubChem - Not safe - “Toxic if inhaled”

Acrolein: Acrolein | CH2CHCHO - PubChem - Not safe - “Very toxic when inhaled”

Polycyclic Aromatic Hydrocarbons - Dibenz[a,j]acridine | C21H13N - PubChem - There are many different types. This is just one of them. “Suspected of causing cancer.” “Suspected of causing genetic defects.”

Perhaps not everyone would buy into what the NIH and CM have to say about what chemicals are released and what effects they may have on the human body. But, I believe these are good sources of information. I’m not willing to risk my own health or the health of my family by failing to use proper ventilation/air filtering. I recommend that everyone either vent to the outdoors or use an air filter.

Sorry, I didn’t mean to imply that one shouldn’t properly ventilate. Wasn’t my intention.
I ended up putting a hole in my garage wall and using a high static pressure fan with a dryer hose and vent to the outside.
The Carnegie Mellon info is pretty incomplete and useless. They group all wood together with plywood and mdf. MDF is problematic for CNC as well as laser. Plywood depends on the glue used. I pretty much only use the laser on hardwood, which typically comes from a tree, dried and without treatment. Occasionally on slate.
They also don’t mention what types and powers of laser they’re using. I would assume they’re dealing with co2 and fiber lasers.
You probably have more formaldehyde in your house from your fabric and furniture than the SM will produce.
As is the case with eye protection for the laser, yes, you’re better to err on the side of caution.

1 Like

Going back onto the original question, what I do to remove that residue is to use a vacuum cleaner with a brush attachment (e.g something like this):

There are ones with harder and softer brushes, I prefer the softer ones for this kind of work. So I put this on top of my vacuum cleaner hose and then turn the vacuum on and vacuum it off. You will need to brush very lightly so to not work the particles into the wood surface. Also make sure that the bristles of the brush are really dry. You will lose a bit of contrast on the image because the black particles are really helping it to pop, but that’s of course no use if you cannot touch them.

Like others have said, having owned and used several large laser cutters: ventilation and filtering is important! We basically only laser cut MDF and used to have a cheapo filtering system and the grime and residue you get in there you really don’t want anywhere near your lungs. Now we have a professional filtering system.

If you live in a residential area in most countries you also have pretty strict rules on what kind of fumes you can release in the wild. Even WITH the filtering system the fumes are not odourless and will be pretty annoying for people living near you.

As for the residue: there isn’t really any way to get it off. Best thing to do is to coat the wood/MDF with a water based sealant. Something like the lacquer you get for wood flooring. Then you can experiment with watering it down and actually dipping the laser cut piece fully into the paint. Again, make sure to only use water-based lacquer. We have some really good results with that and it not only makes the pieces smudge-proof, but also takes away the smell, which usually is pretty terrible. You wont notice it so much at first, but leave something you did on the laser cutter at home and you will definitely notice it.

So don’t be cheap on the safety front. At the very least extract the fumes to the outside.