artists'paint additive rheology

The first paste is made of 100g of pigment + 17g of linseed oil. It exhibits a yield stress and a little elasticity. It is almost a pseudoplastic paint. The second paste is made of 100g of pigment + 19,3g of linseed oil. When shear force is removed, it still flows during a little time when high impasto peaks fall, and paint undergoes a little leveling. In the painter's vocabulary, the first paint is "short" and the second is "long".
The pigment tested here is PW18 "blanc de Meudon". It is used as a filler and a rheology modifier. These pastes can be added in small amounts to pure paint and ground again to obtain different rheological behavior.
Both pastes have been mixed in a mortar with pestle and then finely handground under a muller on a heavy slab.

[@thierrymoutard-martin12]

Pour en savoir plus : sites.google.com/site/moutardmartin/Home/cours-et-formations/broyage-des-couleurs

[@sergioaramos2369]

What is the advantage, to improved impastos or something else?

[@thierrymoutard-martin12]

It gives you an adjustable rheology without adding any oil-resin medium. This paste can be really thixotropic unlike modern oil paints which are pseudoplastic pastes with a clear yield stress but have not the real time dependant thixotropic rheological behavior. It makes really easier the wet in wet working for draperies and carnations.

[@JH-ct9fj]

Please, I have (stupid?) question, was baltic Amber used for anything by the old masters? Can it be a pigment? glue? Can sugar be used as gum, like gum arabic? Will it last? Thank you

[@thierrymoutard-martin12]

Only a little part of Baltic amber can be dissolved. The final product is not a good varnish. Very fragile and brittle. Old treatises'amber is actually copal resin, which is better.

[@JH-ct9fj]

@@thierrymoutard-martin12 Thank you for the answer.