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Using mica in cold process soap

Mica is a name given to a group of silicate minerals, which form distinct sheets and flakes. These are very thin and light, and are most commonly found in schist and granite, giving the rock its shiny, sparkly appearance. It’s this sparkle that makes the mineral so attractive to the cosmetic industry. Although mica occurs naturally, it is very expensive to mine and the cosmetic grade micas, which are used in make up, are often synthetically produced in the lab. Keep this in mind when making claims of natural products!


Synthetically produced mica has the same crystal structure as natural occurring mica in rocks – a very thin, transparent two-dimensional sheet structure. For example, Geotech in the Netherlands, is one such company, which produces synthetic mica for the cosmetic industry. The mica used in cosmetics is usually transparent and colourless, so to achieve the many hues of colours, it has to be coloured with pigments or dyes.

How to use mica in soap making? The general rule of thumb is to use one teaspoon of mica in 500 g of soap. A trick I learned from Soap Queen, is to disperse the mica in a little lightweight oil – I use rice bran oil – and mix it with a electric mini-mixer until you have a smooth paste, and add this to your soap at light trace.

I have a love and hate relationship with micas in soap making. I love the bright, sparkly, and often rich shades, and they are very easy to work with. They don’t clump and don’t speckle the soap. But unfortunately, they are also very fickle in cold process soap, due to particular colourants, pigments, or dyes used to colour the micas, which makes them unstable in the high pH environment of cold process soap making. In other words, you never know what you get. Some micas stay true to their colour, but others morph into other colours, most often grey and brown, and some disappear altogether. The only way to be certain if the mica is colour stable is by testing.

One of my early mica experiments – it should have been bright yellow and green!

Over the next few weeks, I’ll be testing all the micas from Pure Nature in cold process soap and will be posting the results here. And because I also want to have some fun while I’m playing with colour, I’ll be creating some colourful tutorials for you to try out!

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Lakes and FD&C colours

FD&C is an American labelling standard, which stands for Food, Drugs and Cosmetic.  FD&C dyes have gone through rigorous testing, which makes them safe for use in foods and cosmetics, however, they are artificially made (not natural) and I will leave it up to you to decide if they are healthy or not. The main difference between the FD&C dyes and lakes, is that the FD&C dyes are soluble in water and that the lakes are produced from the FD&C dyes and an aluminium salt, which makes the lake oil-dispersible (but not oil-soluble), meaning it can be mixed with oil.

For the following tests, I used lakes from Pure Nature, which are available for $5 for 10 g. These are strong colourants and they will last you for quite a while. Although, I don’t recommend them for cold process soap, you can still use them in other products, such as lotions, bath bombs and melt and pour soaps.

Pure Nature has the following lakes available:

They are all non-toxic, and approved for food and cosmetic use.

Cold process soap

As mentioned earlier, lakes are best dispersed in oil, and will not dissolve in water. However, I tested the lakes mixed with both water and oil, and the results were the same. Just make sure you give the bottle with water a good shake before each use. The usage rate for lakes in cold process soap is 1/8 – 1/4 teaspoon of colour, mixed with 1 tablespoon oil, per 500 g of soap. I used 1/4 teaspoon per 500 g soap in the tests.

You can see in the picture above, that the lakes don’t always perform in cold process soap. The blue lake turned into purple shade after gelling, before gelling it was a greyish shade and the red was orange. The reason for this is that the FD&C dyes don’t like the high pH environment during the soap making process. This is the same reason why food colouring doesn’t work in cold process soap making and some micas can give you funny results. The only lakes that seem to stay true to their colours are yellow and orange, and red only after gelling,  which doesn’t leave you with a lot of options for colour mixing.

Melt and pour soap

Melt and pour bases are finished soap bases to which you only add colour and fragrance. That means that you can’t add extra water or oil to the bases. You also can’t add the powder directly to the soap, because it will leave speckles in your soap.

Pre-mixing the lakes in glycerin, on the other hand, will give you bright, even colours throughout your soap. The colours will stay true, because there is no saponification like in cold process soap, and they are very easy to blend.

The only problem you might come across is when you didn’t mix the colour properly into the glycerin. In this case, you will get speckles at the bottom of the soap. Always mix well and shake bottle before use!

Bath bombs

Lakes are often used to colour bath bombs, because, as powders, they are easy to mix into the dry ingredients and result in brightly coloured bath bombs. To use the lakes, add a pinch of colour to your finished bath bomb mixture. Only add only a tiny amount at a time because they are quite strong in colour. Keep adding until you reach the colour you desire. To achieve the colours in the pictures below, I added 0.3g (two 0.15CC scoops) to 1 cup of bath bomb mixture. As I said, you only need a very tiny amount!

However, using the lakes in powder form will leave the bath bombs speckled, because the colours don’t blend with the other ingredients (remember: not water-soluble). An alternative option is to pre-mix the lakes with glycerin. Glycerin won’t make your bath bombs fizz and it will blend the bath bombs more evenly. Another advantage of pre-mixing the lake with the glycerin is that you can store it for up to a year without having to add a preservative to it.

The colours are a lot more evenly dispersed through the bath bomb, and they mix better than in powder form, as shown in the picture below.

So to summarise, lakes are great for melt and pour bases and bath bombs, as long as you pre-mix them with glycerin. For cold process soap, you have to be aware that they can morph colours and that there are better alternatives out there for cold process soap.

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How to use soap pigments


I’m a big fan of soap pigments. They tend to colour my soap very evenly and are easy to use. They are definitely a lot less messy than lakes and micas, and also a little goes a long way. I would strongly suggest to invest in a trio of soap pigments, if you are into cold process soap making!

I use soap pigments from Pure Nature, which are available for $12 per 10 g. They are a bit more expensive than the lakes and micas, but are a lot more economical and will last you for a long time. They stock the basic three colours: yellow, red and blue, which can be easily mixed to create more colours, such as green and blue.

Soap pigments are water-soluble and very easy to work with. The pigments are mixed with water before use, and then added to the soap at trace. If you pre-mix them, you can store them in the fridge for a week. I use these little mini-bottles from Systema for my prepared colours.

The recommended usage rate for these pigments is 0.02%, which is really a very tiny amount. But I found that you can easily double the usage rate to 0.04% without any trouble – meaning no staining and no coloured foam. To calculate the usage rate into workable amounts, I added 2 mini-scoops (0.15CC each) to 3 teaspoons of water, which gives me exactly 0.02% (MATHS: 0.3 ml / 15 ml = 0.02). Add 1 teaspoon of the solution to 500g soap for a 0.02% usage rate, and 2 teaspoons of the solution to 500g soap for a 0.04% usage rate.

As mentioned earlier, the pigments can be easily mixed to create more colours. For a green, mix one part blue with one part yellow. Add more yellow for a more yellowish grassy green, or more blue for a teal colour. One part red and one part yellow will make orange.

Purples and lavender are a bit more difficult to get right. Purples tend to be more toward the red end of the colour spectrum, so mixing 1/2 red and 1/2 blue usually doesn’t work. With the pigments, I found the ratio 2/3 red to 1/3 blue worked well for me. If you wanted a more reddish purple, you could even increase to 3/4 red to 1/4 blue and increase the usage rate to 0.04%.

Adding titanium dioxide will whiten your soap to make your colour appear more true, as you can see in the picture below. To get the shade of lavender, I added 1 teaspoon of titanium dioxide to 500 g of soap.

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Feijoas from my neighbour’s hedge


I always look forward to March, not only because my birthday is in March, but because that’s when the feijoa season starts in New Zealand. Most people associate New Zealand with kiwifruit and maybe apples, but to me, it’s all about the feijoa. Even when I was in Europe on my big OE (for non-kiwis: overseas experience), I had my mum bring me feijoas when she came to visit me. And she did. She brought a suitcase full of feijoas. I was in heaven!

I have fond childhood memories of feijoas. Many houses in our neighbourhood had feijoa hedges, and come March-April-May, we’d often pick (note: it’s not stealing when the fruit is on the outside!) the yummy green fruit and eat them right there and then. The proper way to eat feijoas is by cutting them in half and then scooping out the fruit with the spoon. But we used to bite of the top and squish the pulp directly into our mouths. That’s why we were experts at picking the best fruit. It had to give way when you pressed it, but not be too soft, because that’s when it would be overripe and past the best taste. If the fruit was too hard, it would be sour. So you had to pick them just right.

Feijoas don’t last long either. I think that’s probably the reason it never got exported and distributed like the kiwifruit. You can keep them in your fruit bowl or fridge for a few days, but no more than a week. They’ll soften and go brown quickly. Especially the pulp, and unlike most fruit, feijoas don’t become sweeter when they’re overripe, they just go bleh.

However, the most mesmerising thing about feijoas is their fragrance. It has such a distinct scent that it’s difficult to describe. I’ve heard people describe it as a mix of various fruits, such as banana/pinapple/strawberry, but you can’t really know what it’s like until you smell and taste the fruit yourself.

Most people will eat the feijoas fresh, but did you know that you can also add them to your muesli and porridge, make sauces, jellies and chutneys, or add them to curries?

Feijoa fruits have high antioxidant activity as they contain significant concentrations of polyphenols (PPs), carotenoids and vitamins. Source

The feijoa is high in vitamins, minerals and anti-oxidants, particular vitamin C and potassium, which makes it a great constituent in skin care products. For a quick and easy skin care trick, after scooping out the pulp, place the skins on your face and leave them on for 10 minutes before rinsing off with water. It’s great for exfoliation and leaves your skin looking fresh and bright.

If you’d like some more ideas, check out the following tutorials: Feijoa soap, which contains fresh feijoa pulp and makes for a great exfoliating shower soap. A delicious feijoa-scented bath bomb with added mango butter to leave your skin amazingly soft. And finally a coconut and feijoa lip balm to keep your lips nicely moisturised (and also tastes yummy!).

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Red, yellow and blue


One of the biggest problems you face when making cold process soaps is colour. The high pH environment of cold process soap making can do some funny things to your colourants. Some colourants, particular natural colourants, will fade to grey. Micas, especially, are a weird bunch. They look beautiful and shiny in their little packet, but once they go into the soap, you never know what’s gonna happen. Some micas turn into the weirdest colours and others will completely fade away into nothing. I’ve had some very disappointing disasters from using micas without previous testing.

The only way you can be certain of a colourant is by doing a colour test beforehand. But that can get expensive. So to make life a little easier for you, I’ll be doing a series of colour tests on micas and other soap colourants available here in New Zealand. And in the end, I’ll put up a handy document for you to download with the different soap colours after curing.

I’m using one of my standard soap recipes, which makes for a nice, solid bar of soap with good lathering qualities. Here’s the recipe:

  • 150 g olive oil
  • 130 g rice bran oil
  • 100 g coconut oil
  • 20 g castor oil
  • 55 g caustic soda
  • 120 ml water

I’m not adding any fragrances or other additives.


For the first colour test I’m using yellow, red and blue granulated soap pigments from Pure Nature. These are available at $12 for 10 g of pigment, and the recommended usage rate is 0.02% of total formulation. This works out to be 0.1 g of pigment per 500 g of soap. Using ratios of 15 cc scoops to 5 ml water, I managed to calculate an amount I could work with.

Pigments are usually water-soluble, so I mixed these in with appropriate amount of water. I then mixed a teaspoon of each colour into the soap, which would give me the exact 0.02% strength I needed.


And this is how the colours appear after a short curing time:

Keep checking back for more colour testing!