Rose hips, ground

David Fisher, The Complete Photo Guide to Soap Making (Creative Publishing International, 2018), p. 20: dyes "give a full range of hues—from subtle to bright and bold", but "can bleed between layers or swirls of soap, especially in melt-and-pour soap. Some are not stable in cold process soap, so test them first"; oxides "are very stable and strong in soap". Natural colours, pp. 82–84. In an infused oil: "Annatto: yellow-orange"; "Alkanet: light to deep purple, depending on the amount used"; "Paprika: orange-peach". In the lye solution: "Indigo: light to deep blue"; "Madder root: pinkish-red"; "Rose clay: deep rose pink". Added to the oils or at trace: "Activated charcoal: light gray to deep black"; "Black walnut hull (ground): speckled brown, also an exfoliant"; "Calendula flower petals (whole or ground): nice, warm yellow"; "Carrots (puréed or juiced): muted orange"; "Cinnamon: reddish tan to brown"; "Cocoa powder: tan to brown"; "Cucumber: pale yellow-green"; "Rosehips (ground): speckled reddish brown"; "Sage: muted green"; "Spirulina: pastel green/blue-green". For "a bright, white bar of soap": "Add titanium dioxide: about 1 teaspoon per 1 pound (454 g) of oils."

David Fisher, The Complete Photo Guide to Soap Making (Creative Publishing International, 2018), p. 19: exfoliants, "Start with 1 to 2 teaspoons per 1 pound (454 g) of oils or soap base"; calendula petals "retain their yellow color nicely"; coffee grounds, "scrubbiness is determined by the coffee’s grind"; "Citrus peel (dried and ground): offers a medium scrub; add at trace"; cornmeal, "medium scrub; premix with oil and add at trace"; eucalyptus leaves, "a medium scrub, especially if not very finely ground"; lavender buds "will turn brown in cold process soap and look like mouse droppings; gently grind them first to avoid this"; loofah, "light to medium scrub"; mint is "prone to bleeding; steep as a tea first"; oatmeal, "like coffee, the scrubbiness is determined by how ground it is"; poppy seeds, "light to medium scrub"; pumice, "heavy-duty scrub; great for mechanic’s or gardener’s hand soaps"; rose hips, "medium to high scrub; also adds natural color"; rose petals "turn black in cold process soap"; sandalwood powder "gives a medium to high scrub, and makes a lovely purple color"; "ground stone fruit pits (apricots, peaches) and berry seeds (ground or whole) give a medium to high scrub factor"; walnut shells, "a nice medium scrub and a lovely medium brown color".

Lovely Greens, natural soap colorants: cinnamon, "use up to 1 tsp ground cinnamon powder PPO. Be aware that cinnamon leaves a slightly gritty feeling"; beetroot, "Warm to dull brown", "Unfortunately, beets do not color CP/HP soap red"; black walnut hull powder, "Add powder at trace and be aware that they create a scratchy or exfoliating texture"; red sandalwood, "Add 1/4-1/2 tsp powder PPO at trace after premixing in a little oil. Can be very scratchy if you use more than this"; woad, "Add 1-2 tsp powder PPO to the lye solution"; rose hips, "Up to 1 tsp ground rosehip powder PPO"; nettle leaf, "muted green", "Premix dried and powdered nettle leaf with a little water and add at trace. Use 1-3 tsp PPO"; kelp, "Dark green", "at trace at up to 3 tsp PPO. Pre-mix in an equal amount of distilled water"; sage, "muted green that fades with time", or "1 tsp PPO dried sage at trace for dark speckles"; peppermint, "1 tsp PPO finely ground peppermint leaves at trace"; liquid chlorophyll, "stunning greens from using about 1 TBSP PPO", fading "into a greeny-yellow"; cucumber, "initially green but usually fades to a muted yellow"; chamomile, "Infuse flowers in distilled water and use the strained liquid to make the lye solution"; green tea, "Brown-green"; rhassoul clay, "Brown"; French green clay, "pale pastel green to earthy green"; "plant-based greens tend to be fugitive". PPO is per pound of oils.

EU: Regulation (EC) No 1223/2009, Article 14(1)(c), a product may contain as colourants only those in Annex IV. US: 21 CFR Part 73 Subpart C lists the colour additives for cosmetics, and turmeric, paprika and spirulina are listed for food only; under 21 CFR 701.20 a true soap, sold only as soap, is not a cosmetic.

NIH Dietary Supplement Label Database, TerraVita Rose Hips Powder (label 282334): "Rose Hip, Powder 1000 mg per 0.25 Teaspoon(s)"; Starwest Botanicals organic rosehips powder: "Daily serving size: 1/4 tsp (1 g)". Rounded to the gram, a quarter teaspoon is 0.5–1.5 g: 2–6 g a teaspoon (0.41–1.22 g/mL).

The labels round to the gram, so a teaspoon could be anywhere from about 2 to 6 g: weigh it.