Spirulina powder

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."

Soap Queen, avocado spearmint soap: 1 tablespoon of spirulina, dispersed in a tablespoon of oil, for 35 oz of oils.

Anne-Marie Faiola, Pure Soapmaking (Storey Publishing, 2016), recipes in chapters 8–10. 100% Castile-Brine Stamped Cube: "1 tablespoon sea salt" dissolved in the water before the lye, for 33 oz of olive oil. Oatmeal Soap for Babies: "2 teaspoons bentonite clay dispersed into 4 tablespoons distilled water" and "2 tablespoons colloidal oatmeal" at thin trace, for 15.1 oz of oils whose olive oil is infused with "2 tablespoons Egyptian chamomile" in a teabag in 14.5 oz of oil, 2 hours in a double boiler. Nettle & Yarrow Upcycle: "2 teaspoons dried yarrow powder dispersed into 1 tablespoon apricot kernel oil" in one of two halves of 24.1 oz of oils. Buttermilk Honeycombs: "3 tablespoons honey" at thin trace for 25.1 oz of oils. Banana Cream Pie Layered Bars: "1.2 ounces banana, 1.5 ounces whipping cream, and 1.5 ounces water, pureed" at thin trace for 35.2 oz of oils, then the freezer "for 24 hours to avoid overheating from the sugars in the banana". Annatto-Yarrow with Embeds: "1 tablespoon spirulina powder" and "1 teaspoon yarrow powder", added "directly to the hot lye-water", for 7.1 oz of oils; "2 tablespoons poppy seeds" in one of two halves of 34 oz of oils. Cucumber Layers: "1 ounce cucumber puree" into the whole batch at thin trace, 22 oz of oils. Gardener Scrub with Coffee Grounds: 50 oz of oils, the batter divided "into four exactly equal sections", one each for "5 teaspoons paprika", "5 teaspoons ground orange peel dispersed into 1 tablespoon of canola oil", "5 teaspoons brewed coffee grounds" and "10 teaspoons green zeolite clay". Indigo-Annatto Negative-Space Funnel Pour: "1.5 tablespoons indigo powder" whisked into the lye-water and "1 tablespoon alkanet root powder dispersed into 1 ounce sunflower oil" at very thin trace, 35.2 oz of oils; "In order to bring out the best color for the indigo powder, the soap must go through a hot gel phase". Black Tea Funnel Pour: 5.5 oz of brewed black tea added at thin trace, 5.5 oz of water for the lye, 33.1 oz of oils. Goat Milk Sunset Burst: "0.7 ounce goat milk powder dissolved in 1 ounce distilled water" for 17.1 oz of oils and "1 ounce goat milk powder" for 25.2 oz, added at trace: "To help avoid scorching, this recipe incorporates the goat milk by using a concentrated solution of powdered goat milk."

Anne-Marie Faiola, Pure Soapmaking (Storey Publishing, 2016), chapter 5, "Herbal and Other Additives for Soap", each at "2 tsp powder per pound of soap": olive leaf powder, "Yellow/green", "Will fade with exposure to light"; comfrey powder, "Light green", "Gel phase enhances the color. Will fade substantially with exposure to light"; nettle leaf powder, "Green"; spirulina powder, "Deep green", "Color is enhanced by a hot gel phase, but will fade substantially with exposure to light"; indigo powder, "Blue/gray", "added as a dispersed powder ... or added directly to hot lye-water before combining oils"; alkanet root powder, "Purple/gray", "Infusion will fade over time; dispersed powder is more color stable"; paprika, "Red/orange", "Gives a speckled appearance"; rose clay, "Rosy pink", "Disperse in distilled water instead of oil"; madder root powder, "Dark red"; yarrow powder, "Yellow/tan", "Dispersed powder can be added at trace, or the dry powder can be infused into lye-water to create a more yellow hue"; cocoa powder, "Rich brown", "Gel phase enhances the color, as does exposure to air". For the chart’s soaps "all powdered additives were dispersed at a ratio of 1 part powder: 3 parts oil"; "The colorants were added at trace and went through gel phase." Oil infusions: "most soapers use at least 2 tablespoons of herb for every 4 ounces of oil. I prefer to use a tablespoon of herb for every ounce." Clay in the water before the lye: "The heat reaction from the lye-water will produce a deeper color than will adding the clay at thin trace".

Humblebee & Me, colouring soap naturally: spirulina green is "prone to fading over time".

Spirulina’s blue, phycocyanin: "thermal treatment can degrade phycocyanin" (PMC11593816).

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.

USDA FoodData Central, food 170495: Seaweed, spirulina, dried.