Apparently using this method a better substitute for using Borax to get a darker engraving with your laser engraver
I tried this so you don't have to and at the moment it's definitely a no from me but, I think more testing is needed. It might work but will not be as effective and quick as Borax.

If you have ever tried this with any success then put it down in the comments section and let me know your process.
I will be trying this again with different speeds and powers to see if it does actually work.