Here are some of the ingredients used in pastels. I believe the “gums” are from plants, but I will let you double-check and research these ingredients.

Dry pastels have historically used binders such as gum arabic and gum tragacanth. Methyl cellulose was introduced as a binder in the twentieth century. Often a chalk or gypsum component is present. They are available in varying degrees of hardness, the softer varieties being wrapped in paper. Some pastel brands use pumice in the binder to abrade the paper and create more tooth.

Don

Casein is (can be) used in manufacturing paints and coatings, but I am not sure if it is used in pastel production. It is derived from cow’s milk. (not almond)

Spectrafix fixative uses casein. Other than that, I don’t know of any other uses of casein in pastels.

Don