The paper in this pad from Clairefontaine is strong

Synthetic Iron OxideLightfastness: ASTM I - ExcellentOpacity: OpaqueGrind: Medium

Colour index: PW4-PW6-PY42

1Viscosity Range: 23000- 27000 CPSCIE L*a*b* Values: L*37

lightfastness and durability

vallejo artist akrylmaling mars violet Size:500ml The paper in this padColour: Mars Violet Permanence: AA Opacity: Opaque Pigment: PR101, PBk11 Pigment description: Synthetic Iron Oxide ASTM Rating Ligthfastness: I Pigment classification: Mixture Color Index Number: Viscosity range (mPa. s): 20. 000 25. 000 Color Index The pigments used for artists' colours are inorganic as well as organic. The inorganic pigments have been used since antiquity; most of them are extracted from minerals and soil, such as natural earth