The Filling Glue Effect On Turquoise Color

Choosing 37 turquoises from 305 turquoise samples ranging from sky blue, blue-green to yellow-green, in order to study the effect of glue filling treatment to the color of turquoise.The.IR absorption spectra has characteristic absorption bands. The bands ascribed to Vas(CH2) asymmetric stretching vibration are observed at near 2931cm-1 and bands ascribed to Vs(CH2) symmetric stretching vibration absorption are observed at near 2857cm-1,as well asν(C=O) stretching vibration bands lie in near 1730cm-1 is the glue filling treated turquoise, natural turquoise does not contain the characteristic absorption bands above.In the light of D65, CIELAB Uniform Chromaticity show that hue angles of turquoise range from 144°to 207°, and concentrate in the Green area and the blue-green area. When transforming light source, b* has the same trend with the color temperature. of light. When color temperature of light reduces from 6504K to 2856K, the b* of sample B29 decrease from 1.4 to -4.69,Δb*=-6.09, the selected samples’Δb* range from7.35 to 3.92. Hue Deviate from yellowish into blue. Changing light source has the same effect on L* and b*. When light source changes from D65 to A, the color of the samples tends to red-blue areas or green-blue area.By water absorption experiment and water lose experiment, the aging of glue filling turquoises and glue filling experiment of natural turquoises. Using colori5 chroma meter to measure the specific changes in the color index, combined with the peak changes of infrared spectroscopy test to study the characteristics of the turquoise filled with glueWater absorption experiment and losing experiment, show that the turquoise’color appearance depends on the content of adsorbed water. The gaining and losing absorbed water relate to the density of turquoise, and density of the turquoise can be measured by water absorption. The turquoise of fast Water absorption speed often has loose structure, whereas the turquoise of slow water absorption speed has dense structure. By measuring the weight of turquoise can calculate the water absorption; dipping test and aging test are irreversible processes, dipping experiment aimed at loose turquoise. After the process of glue filling of natural turquoises, saturation increased, so that the color appearance can be improved. The over-saturation dipping would diminish the luster, if the color difference E<3, the turquoise can be seen as a natural one, because the eye is unable to distinguish the change of color. In the first 100 hours of aging process, yellowing phenomena, and precipitation of white solid appear on the surface of samples, the samples have weak waxy luster, color changed obviously, after 200 hours, the phenomenon is not very clear to see, the color difference is small. Such as BG01, in the aging of first 100 hours, the color difference is 10.87,100 ~ 200 hours 1.65, and 200~300 hours 1.97. Aging process can’t change a glue filling turquoise to a natural one.