It is known that the the control of redox conditions in glass have a strong implication on its final hue, because it affects the Fe2+/Fe-tot ratio. Therefore, an increasing number of studies have been published in recent years by means of synchrotron based X-ray absorption spectroscopy. This is a technique that is not directly accessible and requires dedicated facilities. In this paper we describe an alternative approach by means of optical absorption spectroscopy. We synthesized 10 soda-lime-silica glasses with known redox conditions and iron concentration to calibrate the absorption at 1100 nm in function of Fe2+ concentration. The linear extinction coefficient is also determined. These glasses were also studied with XANES. EPR is also used as ancillary method to verify the quality of our data.