Balsa Foam: Is it laser safe and laserable?



A friend of mine and Glowforge-yearner is a model-maker who just bought a Chinese 60W. He got very interested in Balsa Foam, which looks like fun stuff. (It’s a phenolic foam whose tagline is "Carves Like Butter, Paints Like Wood.)

The MSDS lists these as the hazardous ingredients:

It says this about flammability:

There are also these little tidbits that are potentially relevant:
Odor: Mild (Very low level of formaldehyde)
Inhalation: Remove victim to fresh air. If difficulties continue, contact a physician.
Incompatibility (Materials to Avoid): Contact with metal surfaces in the presence of moisture is
corrosive to that metal. Also may be softened by contact with strong alkali.
VENTILATION REQUIREMENTS: Use in a well ventilated area or with local exhaust for dust and odor control.
TOXICITY DATA: The foam contains low levels of phenol sulphonic acid which, when solubilized, will reduce the
pH of the solvent (water). Otherwise the foam is non toxic.

I’ve Googled its laserability and got nada. To me it sounds like it might not hurt him, but might melt into a gooey mess, and the dust might potentially corrode his machine if it got really humid in there for some reason. @takitus, @volivaa, or others, what is your take?


Sounds like it is laserable safely as long as he has lots of ventilation and is OK with the formaldehyde.
Small amounts are a common in many things (like the glues in a lot of plywoods). Some plastics produce a very high level when burned (formica and phenolic resins come to mind). Most people can deal with small amounts and have no reaction, but it is not good for you over the long term.


Thanks! And, now I know that formaldehyde was named such because of its similarity to formic acid. I’ve never actually smelled it outside of a cadaver lab, so I can’t say whether it smells like crushed ants or not. (Whoa, that sentence came out way creepier than I thought it would. :roll_eyes:)


I’m not sure what that smells like either.

We formed phenolic plastics (bakelite) in the lab in my Industrial Tech class. We embedded metal samples in it to hold them for microanalysis of the steel structure. It has a distinct smell about it. I’m pretty sure thats the Formaldehyde working.


I would urge caution. It sounds like the vapors would not only be corrosive to your machine, but to your lungs as well. Phenolsulfuric acid is a catalyst for protein hydrolysis. IMHO, severe lung edema is likely and probably the effects would be delayed.

On a side note, polymers like those described are useful as ion exchange resins and I have used similar resins to remove lignin from paper mill waste water.


And don’t forget to do the hot wire test before trying to laser it:


The sulphonic acid residual in this plastic may corrode the honey cumb base.

Should wash very well the honey cumb after use of this plastic into the GF.
Also the laser bean may generate SO3 witch can encounter some condensation inside GF and becomes sulfuric acid.
Does not look good!!!