Interference pigments

Question 1

what are interference pigments made of

Answer 1

mica substrate (yellow tinge) with layers of metal oxide (commonly TIO2) and a layer of colourant.
different thicknesses of metal oxide = colour change

Question 2

alternative synthetic substrates

Answer 2

borosilica glass
silica
aluminium oxide (thinner, more uniform, colourless, lower RI than mica)

Question 3

Analytical workflow for interference pigments

Answer 3

–> same up to Raman
SEM EDX - secondary electron mode for the surface topology
- back scattering electron mode for homogeneity
XRF
XRD (for polymorphs)

Question 4

colour analysis

Answer 4

HUE (5 main and 5 middle) eg blue, green and blue-green
VALUE (brightness) 0-10 = black - white
CHROMA (saturation) 0-30 = neutral - fluorescent

Question 5

Interpretation considerations of interference pigments

Answer 5

rapidly changing, context based
no comparison database
substrate considerations
2 way transfer