Even though some of these additives have a strong smell in the raw... once they have been through the rigorous soap making process there is usually no trace of the scent!
Different natural ingredients can produce varying colours by infusing specific plants, flowers or barks in the soap making ingredients. But I warn you, the colours are never startling or really bright. The best that you can expect from natural soap additives is earthy, sludgy, natural looking colours.
Don't necessarily stick to the traditional method of adding the natural colourant at trace. Try infusing the plant in the lye to see what kind of colour you get, or infuse in the base oil at the start. The result may only be subtley different, but equally it could be very different.
This soap has been coloured with carrot juice.
HERE ARE SOME SIMPLE, NATURAL COLOUR ADDITIVES FOR COLD PROCESSED SOAP
Alkanet Root (Alkanna tinctoria)Colour: varies from red through lavender to blue. Alkalinity affects the shade obtained. Alkanet comes as a dried root which should be infused - it is often called natures litmus paper since it turns shades of dark blue in an alkaline environment and shades of red or pink in an acid environment. Because of the natural alkalinity of soap it is very unlikely that you would ever get pink soap from it.
Annatto Seed (Bixa orellana)Colour: varies from Orange to YellowAnnatto comes as dry beads which should be infused in warm oil or lye.
Carrot Juice colour: varies according to how much juice is used... from yellow to orange. Replace some or all of the water content of the recipe for freshly juiced carrots.
Cinnamon (Cinnamomum zeylanicum, Cinnamomum cassia)Colour: warm brown tones.This is the spice we all know from the kitchen. It can be used whole and infused in the oils (I have never tried it in lye) or the powdered variety mixed with a small amount of soap and added to the whole pot at trace.
Cocoa Powder (Theobroma cacao)Colour: warm brown tones.Again this is the stuff we make chocolate drinks from. It is best mixed with a small amount of soap and added to the pot at trace. Like the cinnamon, the effect is often a bit speckly.
Elderberry (Sambucus canadensis)Colour: Berries produce a caramel colour, flowers a soft yellow.Infuse the dry flowers or berries in the lye solution, there seems to be very little extraction of colour by infusing in oil - but this may be because I didn't leave it long enough.
Madder Root (Rubia tinctorum)Colour: pinky red.Madder can be infused in both lye or oil. The main reason many people reject madder is because it contains a substance known as anthraquinones. In small quantities these are used in the treatment of some cancers, however in large quantities they can cause cancer. In reality, you are unlikely to ever use enough of this soap additive for it to have any adverse effect upon your body (especially since soap is a wash-off product).
Paprika (Capsicum annum)Colour: Speckled pink.Yep... this is paprika pepper from the kitchen. Don't use too much as it could produce 'heat' on the skin (outside chance). It should be infused in a little oil and added to the soap at trace.
Rose Hips (Rosa canina, Rosa arvensis, Rosa rubiginosa)Colour: Pink to tan.Rose hips are usually bought ready powdered but if you are planning on preparing your own, dry well first, then ground to a fine powder. Add this to a little soap and return to the main batch at trace.
SpirulinaColour: blue-greenMethod: Add at trace.Add the spirulina to the lye solution or to the soap at trace. It is possible to use too much and give your soap a distinctly 'seaside' smell to it. This does fade over time.
Turmeric (Curcuma longa)Colour: Peach to OrangeAdd to a little of the soap at trace and return to the main batch.
Amounts of soap additive to use:
This is purely a matter of preference, after all, how much colour you wish to see in the final bar of soap? – bear in mind that natural colours will eventually fade out totally and large quantities of spices added at trace could be irritating to the skin.
I would start with approximately 30grams of plant material per kg of oils or 20grams of spices per kg of oils. Keep careful notes and increase or decrease as desired for future batches.
Producing Colour from Plant MaterialFirstly you can't add fresh plant material to the soap mixture. Even hot process soap - which in theory has already cooked out the sodium hydroxide - will turn fresh plants or flowers, petals etc. into a horrid black mush after a very short time. You must always dry any plant thoroughly before considering adding it to the soap. Many plants or flowers when dried will add a decorative touch to the soap but the ones we are talking about here will add colour too.
In order to extract the colour from the plant you need to infuse it. This involves placing a quantity (?how much... how long is a piece of string?) of the plant into warm oil or warm lye solution. This should then be left for a while (?how long... again, how long is a piece of string?) until the colour has leached into the oil or lye. This oil or lye can now be used in the soap recipe.
I am sorry that I can't give you exact times or quantities, but the finished effect is down to you and your experiments - this is what makes soap making so fascinating, and so individual.
soap coloured using powder pigments - watch out for my post on these coming next!