Look at this 60W burn...

[Devil_Master]

Sorry for resurrecting a thread, but I want to learn the theory before starting the practice

Nonsense. Skin reflects/disperses most of the IR. Those with NIR burners can attest to that.

Just don't try that with a 10,6um IR laser... A 16W Synrad, even unfocused, instantly sets fire to anything organic, paint, paper etc. from 3m/10 feet!

Does this mean that certain wavelengths are more dangerous than others?

 

[Cyparagon]

Yes. 50mW of 10.6µm for example is harmless while 50mW of 256nm can be quite dangerous.