Do you have any surplus emulsifiers that you really need to get rid of or any emulsifiers that you really don’t like too much. I have a few of both kinds. One nice project to make out of said emulsifiers is a cleansing balm.  I particularly like wash off balms so this is where emulsifiers come in handy.  I made two types of balms here – they have different emulsifiers.  The first one uses  a combination of glyceryl stearate ( a natural emulsifier) and ceteareth-20 – a not so natural one.  The other one has has Xyliance in it – a natural emulsifier.

Tumeric, Guggul and SheaTumeric, Shea and Guggul

This formulation has Tumeric in it, in powdered form – I got it from the supermarket and is used in lots of Indian cuisine.  I have also used Tumeric co2 extract to add a lovely warm scent which seems to blend really nicely with ylang ylang.  Tumeric is purported to be great for hyperpigmentation as it helps even out uneven skin tone. I have also used Guggul.  Guggul has  anti-inflammatory,  rejuvenating  and  energising  properties – apparently. It is of the same family as Myrrh so you could use that instead or any other essential oil or extract you have laying around.  As long as you follow the manufacturers advice you should be fine.  I have used rice bran oil, again, you could play around with other oils – I am thinking a really slippy oil like almond oil might be a nice alternative.  Good old Shea butter is in there and of course you could try another butter but depending on the melting point you may have to play around with the other ingredients to get the desired consistency.

 

The Formula

Percent UsedIngredient INCI
19.00xyliance Cetearyl Wheat Straw Glycosides (and) Cetearyl Alcohol
15.00Shea butter Butyrospermum parkii
65.00Rice Bran OilOryza Sativa (Rice) Bran Oil
00.10Ylang Essential oil Canaga odorata (ylang) essential oil
00.20Tumeric CO2 extractCurcuma Longa (Turmeric) Root Extract
00.20GlucodOX™ LiquidCommiphora Mukul (Guggul) Resin Extract, Caprylic/Capric Triglyceride
00.50Tumeric powder extractCurcuma Longa (Turmeric) Root Extract

 

Next up is the Fruity one….

Very Berry Fruity CleanserFruity cleansing balm

I used cranberry microzest from Lessonia to colour this balm, it has a lovely understated pink type colour.  Although there is cetereth-20 in it, there are lots of different fruit based oils and butters in here to hide the fact.  I also used gracefruits Gracenotes Strawberry extract which has a very pungent strawberry scent.  You could use Lotioncrafters Goji berry fragrance which is wholly natural and has a very long inci.  So here it is

The Formula

Percent usedCommon nameINCI
09.00Ceteareth-20Ceteareth-20
09.00Glyceryl stearateGlyceryl stearate
03:00Cetearyl OHCetearyl OH
11.00Capuacu butterTheobroma grandiflorum (Cupuacu) Butter
37.00Olive fruit oil Olea europaea (Olive) Fruit Oil
10.00Lemon seed oilCitrus Limon (Lemon) Seed Oil
10.00Papaya seed oilCarica papaya (Papaya) Seed Oil
10.00Blackcurrant seed oil Ribes Nigrum (Blackcurrant) Seed Oil
00.50Cranberry microzestVaccinium macrocarponse seed powder
00.50StrawberryFragaria Vesca Extract

Dont worry if it doesn’t appear to thicken straight away. Give it 24 hours and it will be a nice firm but pliable balm that melts well on warm skin.  If you find that these are not to your liking in terms of viscosity then by all means adjust some of the ingredients.

You will find that it starts to gel around 30c so you have some time to give it a good stir.

Method and equipment needed for both balms

Equipment you will need

A few heat proof bowls, thermometer, something to stir (though I use my themometer), 100g glass or plastic jar, hot plate or hob.  A double boiler (this will allow you to have better control of the temperature).

Method:

  1. Weight ingredients except essential oils in a heat proof bowl.
  2. Heat until all ingredients have melted and stir
  3. Allow to cool to 45c and add the essential oils/co2 extracts
  4. Decant in a wide mouthed container
Important info

I have not done stability tests on them so can not attest to them separating but they seemed fine for the few days that I had them sitting around at room temperature.  If you find there is any separation then you can increase the viscosity by replacing some of the liquid oils with more butters or even using cetearyl alcohol instead.  A nice sub for cetearyl is Kokum butter as it has a very high melting point. You could also try using waxes like carnauba wax or beeswax.

 

 

Have you ever had a product change colour, a cream separate into oil and water or the smell of a product change? I have.  The most recent one was with a natural dupe I did of a Lush shampoo bar. I had used Spirulina as the colourant  and  in about a week the colour had faded.   I have had creams separate over time and had them turn pink due to the preservative. Luckily, I have the ability to do stability testing on products now which saves me an awful lot of time.  But previously I have had to wait and see.

So, what is a stability test and why do we need them?

A stability test is  a way to find out over a period of 1 to 3 months whether a product will hold up during its intended lifetime.  These are called accelerated tests that put the product under extreme conditions and are supposed to indicate how long the product would last under real life conditions.  So, if we want to give a shelf life to a product and we also want to get that product to market in 6 months then we will need to check that nothing will change to the to it over time.  We need to know that it will smell and look the same, it’s viscosity is unchanged, it’s pH is the same (will indicate chemical changes which we don’t want).   We will also need to know if the packaging is right for the product (it doesn’t leak) or that it is generally compatible with the ingredients.  We might also need to know whether it will stand up to ongoing insult from the consumer.  There is also  preservative efficacy testing (PET) or challenge tests which will determine whether the product is microbiologically sound – but that is a whole different post.

When to do a test.

Normally, we should do stability tests on all new products.  We should also do stability tests if we need to change an ingredient or packaging. We would need to do one if we are making scale up batches or if we have a change of machinery or processes.

So how does this happen?

According to some sources there is little published research into how to conduct a stability test, this is because of the great variation between different products.  It is generally up to the manufacturer to agree their own protocols on determining when it is appropriate to do a stability test and how that test should be conducted, depending on the type of product they are testing.  A salve or balm which has no water in it and is expected to melt at high temperatures and will have different parameters than an emulsion which is inherently unstable.  That said there are some guidelines offered by the pharmaceutical industry which have informed the cosmetic industry and there are some useful guides by the FDA and COLIPA.

What to do

So, generally speaking it involves making a batch of product and separating it into a number of different containers and storing it at different temperatures and conditions.  You need to keep one which is your control.  You test and record the control sample for viscosity, pH, scent profile and keep it in the cupboard to test against the ones you put under stress.

Colipa advises that the product is put in an oven at 37c, 40c and 45c.  Depending on who you ask, or what protocol you are following, a product at a different temperature over a certain period will indicate a different shelf life, there is actually no prescription (of a few different ones.)  So we can say that one month at 40-45c will indicate 1 year at room temperature – or thereabouts.  As a little side note, in the EU, in order to get a period after opening sign on the product we need to know that the product will be durable for 30 months minimum, so it would need to pass the 3 months in the oven with no significant changes.

There are also tests like the freeze thaw cycle which are supposed to be good for testing liquid products.  This is where a product is put in a freezer at -10c for 24 hours and then left to to thaw at room temperature.  This can be done over 3 cycles – that is three times in the freezer and three times at room temperature.  There are also vibration tests which test that the product won’t leak out of the intended container and UV tests that will assess how sunlight will affect the product.

Unconventional ways to do stability tests.

It can be quite costly to do stability tests. Most manufacturing companies have their own in-house equipment and protocols to test for stability but if you are just starting out you might not have the budget and will need to get them sent off for testing. This is always advisable, but it can be expensive if you have to keep repeating the tests in the event of failed tests.  So it is good to be able to get formal testing done only after you have done your own preliminary tests.

Stability testing on a shoe string

Oven test

There are reptile incubators that cost about £150 which can be great to conduct your own oven tests.  Set it to 40c and keep a sample in there for 3 months. Check it every few weeks against your control (which will be in the cupboard.)

Vibration tests

Put your product in its intended packaging and send them to a friend who lives far away and ask them to send them back to you. If they live in a warm country, the product will be shipped on a cold plane and then might be waiting around in heat at the destination. Baggage handlers will probably throw your product around a bit and there will be a lot of vibration when on the plane and on the van.

You can also buy chicken egg incubators which vibrate and turn eggs at a warm temperature. You could probably do that for a few days and see what happens?

Freeze thaw cycle

Most people have a freezer. Put your product in the freezer for three cycles. Simple.

UV Test

Put one sample in a clear glass container and one in the container intended for sale.  Leave them on the window sill for 3 months and check regularly to see any change in colour.

How to test

You don’t need any fancy machinery. Okay, so in the industry they have viscometers to check the viscosity and other fancy stuff.  But you don’t really need all that to do your own preliminary tests.  You just need your eyes, nose, skin and a pH meter.   Simply, take your product out of the oven or freezer and leave it at room temperature for 24 hours. Then test it against your control.  Does it smell the same?  Does it look the same? How does it feel? Is the pH as expected?

Remember – it is your test, you decide the parameters.  You are going to expect some changes to your product.  But you have to decide whether those changes are acceptable.  For instance, when it comes to pH – being +/- 0.1 pH might be ok if your product is supposed to be between pH 4.6-5.2.  It may come out of the oven having started at pH 4.8 but the pH has dropped by 0.2 units making it pH 4.6.  You may have decided that as long as it stays within a certain range it is acceptable.  Similarly, if you notice  that the colour has changed only slightly, this might be acceptable too.

Record your findings at every stage – Create a form with dates, times and places to describe changes, if any, you have seen.  You can even take pictures and attach them to your form!

Real time tests / Samples

Even the big guns keep samples for the expected lifetime.  They will make the initial batch and keep them in a storage cupboard.  After each batch of product made for market they will keep a sample of that batch too. This is good practice.

Below is some other more in depth reading on the subject.  Enjoy 🙂

FDA guide

COLIPA Guidelines on stability testing

Slideshare – stability tests on drugs

Presentation on stability testing