Soap additives
Everything that goes into soap besides the oils, the lye and the water: acids and chelators, salts and sugars, milks, juices and purées, clays, colours, herbs and scrubs. Each page says what the additive is for, how much of it its sources use, when and how it goes in and what it does to the lye and water. Every dose is given in its source’s own terms, with the source named.
Every figure names its source and what kind it is: a primary source, such as a data sheet, a regulation, a paper or a published book, or a supplier or soapmaking guide. None comes from another soap calculator.
Mineral colours
- Activated charcoal
Light grey to deep black.
- Black iron oxide
Black.
- Brown iron oxide
Brown.
- Chromium oxide green
Green.
- Hydrated chromium oxide green
Green.
- Mica (pearlescent)
Shimmer. A spectrum of bright hues; it shows best in clear soap.
- Red iron oxide
Red.
- Titanium dioxide (oil-dispersible)
Opaque white.
- Titanium dioxide (water-dispersible)
Opaque white.
- Ultramarine (blue, violet or pink)
Blue, violet or pink.
- Yellow iron oxide
Yellow.
- Zinc oxide
White.
Plant colours
- Alkanet root
Light to deep purple.
- Annatto seed
Yellow-orange to dark orange.
- Beetroot powder
Brown, though pink in the jar.
- Black walnut hull powder
Speckled brown. A scrub.
- Cinnamon, ground
Reddish tan to brown.
- Cloves, ground
Light brown.
- Cocoa powder
Tan to brown.
- Indigo powder
Light to deep blue.
- Kelp powder
Dark green.
- Liquid chlorophyll (copper chlorophyllin)
Mossy to bright grass green.
- Madder root powder
Pinkish red.
- Nettle leaf, powdered
Muted green.
- Olive leaf powder
Yellow-green.
- Paprika
Orange-peach.
- Red sandalwood powder
Purple. A medium to strong scrub.
- Rose hips, ground
Speckled reddish brown. A medium to strong scrub.
- Spirulina powder
Pastel green to blue-green.
- Turmeric powder
Golden orange, fading to a muted gold.
- Woad powder
Pale blue-green to deep denim blue.
- Yarrow powder
Yellow to tan.
Dyes and glitter
- Cosmetic glitter
Shimmer.
- Soap dyes (water-soluble, liquid)
Any hue, subtle to bright; dyes tint transparent soap too.
Clays
- Bentonite clay
Slip and glide, for shaving soap. More lather, with a creamy touch.
- Dead Sea mud (dry powder)
Sold for facial cleansers.
- French green clay
Pale pastel green to earthy green.
- Kaolin clay
A little gives the soap a silky feel; too much makes it slimy.
- Red clay (illite)
Red.
- Rhassoul clay
Brown. Sold for facial cleansers.
- Rose clay
Deep rose pink.
- Sea clay
Green.
- Yellow clay
Yellow.
- Zeolite (green zeolite clay)
Green.
Exfoliants
- Alfalfa meal
A gentle scrub.
- Almond meal (ground almonds)
A scrub.
- Apricot seed powder
A medium to strong scrub.
- Bamboo sap powder
A gentle scrub.
- Berry seeds (raspberry, strawberry, cranberry)
A medium to strong scrub.
- Coffee grounds (used, dried)
Its grind decides how hard it scrubs.
- Cornmeal
A medium scrub.
- Flax seed meal (ground flaxseed)
Its grind decides how hard it scrubs.
- Ground loofah
A light to medium scrub.
- Ground oats
Its grind decides how hard it scrubs.
- Jojoba beads
A scrub.
- Jojoba meal
A gentle scrub.
- Lemon zest (finely grated)
A light to medium scrub.
- Loofah sponge (whole, dried)
A medium to strong scrub.
- Orange peel powder (dried, ground)
A medium scrub. For looks: specks in the soap, or scattered over the top.
- Poppy seeds
A light to medium scrub.
- Pumice powder
A heavy-duty scrub, for hand soap.
- Walnut shell powder
A medium scrub. Medium brown.
Milks and cream
- Almond milk (unsweetened)
Replaces some or all of the water.
- Buttermilk (cultured, low-fat)
Replaces some or all of the water.
- Coconut milk (canned)
Replaces some or all of the water.
- Goat milk
Replaces some or all of the water.
- Heavy cream (36 % fat)
Replaces some or all of the water.
- Oat milk (unsweetened)
Replaces some or all of the water.
- Plain yogurt (whole milk)
Replaces some or all of the water.
- Whole milk (3.25 % fat)
Replaces some or all of the water.
Milk powders
- Buttermilk powder
Milk soap from a powder instead of liquid milk.
- Coconut milk powder
Milk soap from a powder instead of liquid milk.
- Goat milk powder
Milk soap from a powder instead of liquid milk.
- Whole milk powder
Milk soap from a powder instead of liquid milk.
Other liquids
- Aloe vera juice
Replaces some or all of the water.
- Beer (flat, boiled)
Replaces some or all of the water.
- Black tea (brewed)
Replaces some or all of the water. Tan to brown.
- Carrot juice
Replaces some or all of the water. Muted orange.
- Coconut water
Replaces some or all of the water.
- Coffee (brewed)
Replaces some or all of the water. Brown.
- Dandelion infusion (for the lye)
Replaces some or all of the water.
- Green tea (brewed)
Replaces some or all of the water. Brown-green.
- Lemon juice (fresh)
Replaces some or all of the water.
- Lime juice (fresh)
Replaces some or all of the water.
- Orange juice (not from concentrate)
Replaces some or all of the water. Golden, at a quarter of the water.
- Red wine
Replaces some or all of the water. Dark tan.
- White wine
Replaces some or all of the water.
Purées
- Avocado (mashed)
Brings fat of its own into the bar. Label appeal: a soap made with a favourite fruit or vegetable.
- Banana (mashed)
More lather.
- Carrot purée
Muted orange.
- Cucumber purée (with peel)
Replaces some or all of the water. Pastel yellow-green.
- Pumpkin purée (canned)
Soft orange.
- Strawberry purée
Label appeal: a soap made with a favourite fruit or vegetable.
- Tomato paste (canned)
Orange to red. Label appeal: a soap made with a favourite fruit or vegetable.
Sugars and glycerin
- Glycerin (99 %)
Transparent soap. In hot process, it helps the cooked soap flow.
- Honey
More lather.
- Sorbitol (70 % solution)
More lather.
- Sugar
More lather.
Salts and hardeners
- Baking soda (sodium bicarbonate)
A gentle scrub.
- Borax (sodium tetraborate decahydrate)
In liquid soap: takes up spare lye and thickens the soap.
- Epsom salt (magnesium sulfate)
A bath-salt and bath-bomb ingredient; its soap sources advise against it in bar soap.
- Himalayan pink salt, coarse
For looks: specks in the soap, or scattered over the top. Salt bars: very hard, dense bars.
- Kosher salt, coarse (Morton type)
A harder bar that unmoulds sooner.
- Kosher salt, flaked (Diamond Crystal type)
A harder bar that unmoulds sooner.
- Salt, fine (table or canning)
A harder bar that unmoulds sooner. Salt bars: very hard, dense bars.
- Sea salt, coarse
Salt bars: very hard, dense bars.
- Sea salt, fine
Salt bars: very hard, dense bars. A harder bar that unmoulds sooner.
- Sodium lactate (60 % solution)
A harder bar that unmoulds sooner.
- Sodium lactate (powder)
A harder bar that unmoulds sooner.
- Washing soda (sodium carbonate, anhydrous)
A harder bar that unmoulds sooner.
Chelators
- Disodium EDTA
Binds hard-water minerals, for less soap scum.
- GLDA (47 % liquid)
Binds hard-water minerals, for less soap scum.
- Sodium citrate
Binds hard-water minerals, for less soap scum.
- Sodium gluconate
Binds hard-water minerals, for less soap scum.
- Sodium phytate
Binds hard-water minerals, for less soap scum.
- Tetrasodium EDTA
Binds hard-water minerals, for less soap scum. Sold to hold off rancidity and orange spots.
Antioxidants
- BHT (butylated hydroxytoluene)
Sold to hold off rancidity and orange spots.
- Grapefruit seed extract
Sold to hold off rancidity and orange spots.
- Rosemary extract (ROE)
Sold to hold off rancidity and orange spots.
- Vitamin E (mixed tocopherols)
Sold to hold off rancidity and orange spots.
Acids (they take lye)
- Citric acid (anhydrous)
Binds hard-water minerals, for less soap scum.
- Citric acid (monohydrate)
Binds hard-water minerals, for less soap scum.
- Lactic acid (88 %)
A harder bar that unmoulds sooner.
- Vinegar (5 % acetic acid)
Replaces some or all of the water.
Herbs and flowers
- Calendula petals (dried)
Warm yellow. For looks: specks in the soap, or scattered over the top.
- Chamomile flowers (dried)
For looks: specks in the soap, or scattered over the top.
- Comfrey leaf powder
Green.
- Dandelion petals (dried)
For looks: specks in the soap, or scattered over the top.
- Eucalyptus leaf (dried)
A medium scrub. For looks: specks in the soap, or scattered over the top.
- Lavender buds (dried)
For looks: specks in the soap, or scattered over the top.
- Peppermint leaf (dried)
For looks: specks in the soap, or scattered over the top.
- Rose petals (dried)
For looks: specks in the soap, or scattered over the top.
- Sage, dried (rubbed or ground)
Muted green, or dark specks.
Other
- Colloidal oatmeal
Oats too fine to scratch: you can barely feel them in the bar.
- Egg yolk (raw)
Said to make the lather richer and thicker, though one maker who tested it with care finds the effect small. Brings fat of its own into the bar.
- Ethanol (95 %, 190 proof)
Transparent soap.
- Soap shreds (grated soap)
For looks: specks in the soap, or scattered over the top.
- Tussah silk
Said to give the lather a silky feel, though not every maker notices it.