Conservators use the refractive index measurement for a range of purposes. It can provide information about the chemical composition of the glass. Lead glass, for example, has a relatively high refractive index of approximately 1.550 to 1.570.
Refractive index measurements help conservators choose a suitable adhesive for crack impregnation, bonding fractures or filling gaps. An adhesive with a similar refractive index makes a repair less visible. Epoxy adhesives, for example, often work well with lead glass. Conservators also consider stability when choosing an adhesive.
A refractometer measures refractive index and is also used for gemstones and other stones.
Tennent, N. H., Townsend, J. H., The significance of the refractive index of adhesives for glass repair, Studies in Conservation, 1984, 29(sup1), 205–212. doi.org
