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Testing Fragrances Part 2

In part 1, I discussed vanillin discolouration, but it is quite possible to have a fragrance with 0% vanillin that will still discolour your soap. Fragrances are comprised of many different components, some contain 100 or more ingredients to make up a unique scent. Any of these can affect the colour as well as other aspects of soap, which is why not all fragrances are suitable for soap making. Fragrances that are considered safe to use in soap making must be skin-safe, suitable for cosmetic use and have undergone strict testing to comply with international standards. Only source your fragrances from responsible distributors, such as Pure Nature, who can provide safety data and certification from their suppliers.

Even if the fragrance doesn’t contain vanillin, they can still cause discolouration, as the different shades of white of these soaps show.

To create a fragrance, different essential oils, resins, as well as natural and synthetic aroma chemicals are mixed together to a unique blend. Unfortunately, in most countries, fragrances do not need to list their exact constituents, because it falls under ‘trade secret’, so we usually don’t know what exactly is in them. Certain components will change the colour of your soap, just like vanillin, but because we don’t know the exact make up of the fragrances, it is difficult to pinpoint which component causes discolouration or even to predict what a fragrance will do to the soap.

The top soap was an early test for one of my tutorials and instead of remaining white, turned a rather bright yellow during the curing time. The fragrance contained no vanillin, yet still caused significant discolouration.

The most common discolouration from a non-vanillin component is off-white, ivory or a creamy colour, although there are other possible colours as well. Oakmoss and amber, from Candlescience, for example, can cause your soap to turn a shade of mauve.

Then, there are some fragrances or components of fragrances, which have a natural tint to them and can also discolour your soap. For example, orange essential oils range from yellow to bright orange in colour, which may cause soap to turn yellow. In general, my rule of thumb is if the fragrance is not clear, that’s a warning sign! But that doesn’t mean that all tinted fragrances discolour, just like not all clear fragrances won’t discolour. And to complicate matters further, your soap recipe, the oils you use, your soaping method and the temperature can all have an influence as well. This is why you often get conflicting reports of fragrance discolouration. The only fail-proof method is to test a fragrance using the exact recipe and method yourself, to be absolutely sure of no discolouration. However, in most cases, slight changes don’t matter that much, and for the extreme discolourations that vanillin causes, looking up the vanillin content, or reading the fragrance reviews are often a good help. Or you can go for one of the water white fragrances.

Although not a water white fragrance, the discolouration is only subtle and doesn’t distract from the overall design.

Water white fragrances are fragrances that are clear liquids, have 0% vanillin content and cause no discolouration.  There is no standard that labels these fragrances as such, and the only way to know which fragrances are water white fragrances is usually from testing or from test results that other soapers have done for you.

Here are four Candlescience Skin-Safe fragrances that can be considered water white fragrances:

And lastly, another option is to add titanium dioxide to your soap. Titanium dioxide acts as a whitener in your soap, although it will only work on light discolourations. It won’t magically turn your brown soap into the pure white! The good thing is that you only need a tiny amount to counter the discolouration, I use a maximum of half a teaspoon in one kilo of soap. Don’t use too much or you’ll end up with the unsightly glycerin rivers. Incidentally, titanium dioxide added to micas can make the colours pop, stand out more!

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Coffee soap

Difficulty: intermediate
Time: 1 hour
Yields: Approximately 1200 g soap (10 bars)


Here in New Zealand, we drink our coffee as a flat white, which is one shot espresso with steamed milk. I tried to recreate our beloved flat white in this soap using Espresso Fragrance and coffee grounds, and layering and swirling the soap to give it the appearance of pouring the steamed milk into the coffee.

Most coffee fragrances will turn your soap brown due to the vanillin component in the fragrance. The fragrance I’m using in this soap is the Fresh Coffee fragrance from Candlescience, available from Pure Nature, which discolours to a caramel colour. To prevent the whole soap becoming one colour, there are three different layers in this soap:

Layer 1: unscented, which will remain creamy white
Layer 2: scented, which will turn caramel
Layer 3: scented with added coffee grounds, which will be slightly darker than layer 2

This kind of layering technique is a particular useful method for fragrances that cause discolouration and when you want to keep part of the soap white. However, be aware that the fragrance ‘travels’ through the soap and the lines between the scented and unscented layers will become more diffuse over time as the fragrance moves into the unscented layer. Even so, it will never become the same darker colour as the scented layer.

If you have never made cold-process soap before, I strongly suggest you check out the basic cold process soap tutorial first.

Before starting, please read the safety and precautions post, especially since this tutorial requires the handling of caustic soda!


ONE: To prepare your lye, add 250ml water in a small pyrex or other heat proof glass jug, and weigh out the caustic soda in a separate small container. Then, carefully, add the caustic soda to the water and gently stir until all the caustic soda has dissolved. Set aside.


TWO: Weigh out the coconut oil and cocoa butter in a large, heat proof Pyrex jug, and heat it in the microwave until they have melted. Weigh out and add the liquid oils.


THREE: Make sure you are still wearing protective goggles and gloves. Then, when the lye and oils have cooled down to room temperature, add the lye to the oils and give it a good stir with a whisk until the soap mixture has emulsified. Don’t use a stick blender, because we don’t want the soap mixture to become too thick to work with and the fragrance that will be added later will slightly accelerate (thicken) the soap additionally.


FOUR: Separate approximately a quarter, around 250-300 ml, of the soap mixture into a separate container or jug. This portion will remain unscented, so that it will stay white.


FIVE: To the remaining soap, add the fragrance and give it another good stir.


SIX: Again, separate around 250-300 ml of soap into a second container. Because this portion has been scented, it will turn a caramel colour.

You should have about half of the soap left in the jug, around 500 ml. Don’t worry if it’s a bit more or less.

SEVEN: Add the coffee grounds to the remaining soap mixture and give it a good stir.  I used one teaspoon of unused coffee grounds. This portion of the soap will be the darkest colour due to the coffee grounds. If you wish for an even more darker colour, soak the coffee grounds in one teaspoon of water before adding it to the soap. The water will turn a dark brown from the coffee, which will colour the soap.

You should now have three portions in three different jugs/containers: two smaller portions, one unscented and one scented, and a bigger portion (about half of the soap mixture), which is scented and contains coffee grounds.

EIGHT: To assemble the soap, pour the layers on top of each other, adding more of the scented, coffee grounds portion, and only one layer of white soap in the middle of the soap. Leave about a third of the white soap to use later.


NINE: This part it optional, but I like the broken, discontinued layer effect it created in the soap. Using a hanger tool, move it up and down along the length of the soap several times.


TEN: Once you have swirled the soap, spoon the remainder of the white, unscented soap on top, and with the spatula or spoon, fluff the soap a bit to create peaks of soap. Sprinkle some coffee grounds over the top. I had wet hands, so my coffee grounds got a little wet and clumped together when I tried to sprinkle it over the soap.


ELEVEN: Leave the soap to harden for a few days before unmolding and cutting it into bars. Cure the bars for another 6-8 weeks before using.


Flat white soap

  • Difficulty: intermediate
  • Print
Before starting, make sure you wear protective goggles and gloves and work in a well-ventilated area, free from any distractions!


  • 400 g olive oil
  • 250 g coconut oil
  • 200 g rice bran oil
  • 100 g cocoa butter
  • 50 g castor oil
  • 137 g caustic soda
  • 250 ml water
  • 40 ml Fresh Coffee fragrance
  • 1 teaspoon ground coffee


  1. Prepare your lye: carefully add the caustic soda to the water and stir gently until all the caustic soda has dissolved. Set aside.
  2. Weigh out the coconut oil and cocoa butter in a heat proof pyrex jug and heat in the microwave until completely melted.
  3. Weigh out and add the liquid oils to the melted coconut oil and cocoa butter. Set aside.
  4. When both the lye and oils have cooled down to room temperature, and making sure you are still wearing protective goggles and gloves, add the lye carefully to the oils, avoiding any splashes.
  5. Using only a whisk, stir the lye/oil mixture until it has emulsified.
  6. Separate around 250 ml of the soap mixture in a separate container.
  7. Add the fragrance to the remaining soap and give it a good stir.
  8. Separate around 250 ml of the scented soap mixture into a second container.
  9. To the remaining soap, which should be around 500 ml, add 1 teaspoon of coffee grounds and stir. You should now have 3 portions of soap in 3 separate jugs/containers: 1 unscented, 2 scented, 3 scented and with coffee grounds.
  10. Layer the soap into the soap mold, using more of the scented, coffee grounds portion and leaving around 1/3 of the unscented soap for later use.
  11. Optional: use a hanger tool to break up the layers by moving it up and down along the length of the soap several times.
  12. Scoop the remainder of the white, unscented soap on top and fluff it up to create peaks. Sprinkle some coffee grounds over the top.
  13. Leave to harden for several days before unmolding and cutting into bars. Let the bars cure for another 6-8 weeks before using.

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Testing Fragrances Part 1

Why test fragrances? Fragrances can wreak all sorts of havoc in soap making due to the many different components that make up a fragrance. Fragrances can discolour soap, can raise the temperature during the saponification process, can increase acceleration and cause seizing, just to name a few possible problems. But don’t think essential oils are any different, these issues can also arise when using particular essential oils! Here, I’ll be discussing why and how these problems are caused and how to prevent them. And as an extra bonus, I’ll post the results of the Candlescience Skin-Safe Fragrances, available from Pure Nature, that I’ve tested in the past month, to help you choose the right fragrance for your next project.

The main problem for soap makers is discolouration in soaps. The discolouration is usually caused by the ingredient vanillin, which the primary component of the vanilla bean extract, the bit that gives vanilla its unique scent. Fragrances that contain vanillin will inevitably turn to brown. How much the discolouration and how quickly a soap will turn brown, depends largely on the percentage of vanillin a fragrance contains. Fragrances with a high percentage of vanillin, 10% or more, will turn to a dark brown, whereas those with only a small amount, less than 1%, will only discolour slightly and often only after some time has passed, which is why fragrance testing takes a while. You only know the full extent of the discolouration after a soap has been completely cured. Incidentally, discolouration also affects melt and pour soap bases and other skin care products. The reason for the discolouration, as it often is, is caused by the villain oxidation. Oxidation occurs when chemicals react with the natural oxygen present in the air. You could, of course, try and wrap your soaps airtight, but that would only work for a limited time and only with melt and pour soaps and lotions. Cold and hot process soaps need to cure, which can only happen if they’re unwrapped. And curing causes discolouration…. see the dilemma?


In the above two pictures, you can see vanillin at work. The picture on the left was taken after 1 day of curing, the picture on the right after 5 days. Discolouring will continue until the whole soap has become the same colour as the edge. Vanillin discolouration is a totally natural process, and you cannot prevent it from happening. But there are chemicals that can slow this process down. They don’t completely eliminate the discolouration, but can stabilise the fragrance and postpone the discolouration for several months. Now if you’re like me, I’d like my soap to keep looking like it did when I gift or sell it, and having it turn brown in someone’s pretty soap dish after half a year seems a bit misleading to me. Nevertheless, if you would like to explore this option, the product is called Vanilla Colour Stabiliser, and it works by counteracting the oxidation of the vanillin, but as I mentioned before it won’t last for ever. The longest I have seen it working was about half a year.

The much better solution is to work with the discolouration. If you know the fragrance will turn your soap in a shade of beige, caramel or brown, use this in your design. You can leave a small portion of your soap unfragranced, which keeps parts of your soap white. For example, adding a white swirl or white layer in your otherwise brown soap. A fragrance that only discolours slightly can be ‘coloured over’ with other colours, such as oranges and reds. However, remember that some colours don’t mix well with brown shades. Green, for example, mixed with brown will result in a rather unpleasant shade. And lastly don’t forget that often those fragrances that contain high percentages of vanillin, tend to be fragrances that we naturally associate with warm, brown colours anyway: creme brûlée, chocolate, and anything vanilla or custard-like.

Check out this cool Pumpkin Spice Soap, which uses the fragrance to enhance its design.

If you absolutely do not want your soap to discolour in any way, I suggest you choose a water white fragrance – fragrances that are clear in colour, contain no vanillin, and do not cause discolouration. More about this next week!