A 2001 medical paper by some researchers whose work has always impressed me confirms that dark hair is probably the most important factor in laser effectiveness. Their studies on lasered skin showed that penetration “appeared to be a function of wavelength and not fluence.”
</font><blockquote><font size=“1” face=“Verdana, Helvetica, sans-serif”>quote:</font><hr /><font size=“2” face=“Verdana, Helvetica, sans-serif”> Studies reported to date have shown a good depilatory response from patients treated with the normal mode ruby laser (NMRL) over 12 weeks, but a low response over a time period greater than this.
The implications of this study are that it is probably the presence of the correct chromophore in large enough amounts which is required for successful permanent depilation to occur. </font><hr /></blockquote><font size=“2” face=“Verdana, Helvetica, sans-serif”>PubMed: Topping, 2001 (Ruby laser skin penetration study)