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From Sand To Silicone

July 10, 2016


The above article was brought to my attention this week by a customer that had questioned my response to her and, who most probably felt that I was wrong to dispute this article given that it appeared in an industry focused magazine.

So what and who do we believe?

Well firstly let me say this, not me, well not straight away anyway!  In my initial response to my client I got things only 1/2 right.  Having worked with silicone manufacturers for some years I understood that silicones are anything but natural and immediately interpreted the highlighted sentence as suggesting that silicones were just dug up from sand and as close to nature as you could get.  I let a bit of prejudice get in the way of a decent bit of research for a moment.

So before I go into my investigations I want to remind myself as much as you reading this that ‘belief’ shouldn’t come into this:


If, as a scientist I ‘go’ with my belief system I am acting on what the scientific world calls bias.  This is not at all helpful as bias and belief tends to lead us up to the destination we already knew was right in our head regardless of the proof we find.

As I mentioned,  I reacted strongly to the wording of the article and answered without thinking from first principles.   I offered up a half-baked answer in around 1/2 an hour. This time it has taken me over three hours of reading, thinking and writing.

This is how I should have answered my client all along……

So the first thing I have to do is work out what the article is saying:

‘Manufacturers and consumers often mistakenly believe that silicones are oil-derived petrochemicals, whereas they are actually synthetic products prepared from sand or quartz.’

Before we question what people think it is imperative we work out what we mean when we say ‘silicones’.

In order to fully answer the ‘what is a silicone’ question we need to look at how the first silicone fluids are made and then go from there.  This is something that is relatively easy to do (look up) as the information is in the public domain – see here from Dow Corning.  However, understanding it is another matter entirely.

Silicone fluids – technically known as Polydimethylsiloxanes.

A polymer (lots) made up from silicon, oxygen, hydrogen and carbon.


So how are these silicone fluids made?

If only it was as easy as crushing sand……..

The manufacture of silicone fluids is complex, energy intensive and multi-stepped.  So much so that, even if the starting materials for silicone fluids are natural it is highly unlikely that a silicone fluid could even meet a reasonable definition of a ‘naturally derived’ cosmetic input if indeed that matters.

  1. Methyl Chloride.  Produced in a couple of ways but always by reacting methanol with hydrochloric acid. This could use methanol from vegetable sources as in biofuel production and hydrochloric acid from salt.  All natural but the energy required is tremendous and this type of reaction is typically carried out in huge industrial plants typical of the chemical industry natural cosmetic lovers are wanting to avoid.  A 2004 report from the USA told there were 18 Methanol plants in operation most of which were sourcing their methanol from natural gas with the rest sourcing it from coal.  Basically, all things being equal it is price that drives the choice.
  2. Silicon Metal.  Silicon is an element in its own right and in its pure form is a silvery metallic solid (chemically a metalloid).  Even though Silicon is the eighth most common element on earth it is rarely found in metalloid chunks and instead chooses to bond with other things and form silicates (clays, feldspas, zeolites) or silicas such as quartz – the main component of sand.  So, before we can start making polydimethylsiloxanes (silicones) we have to extract the silicon from sand.  As an example, silicon is extracted from sand here in Australia –at the Western Australian based Simco Operations.   The key step in this process is to break the Si-O bonds in the silica (SiO2), this is done by blasting the silica with a carbon rich furnace.  The carbon is usually from quartz, charcoal, coal, petroleum and wood chip.  This reaction occurs at 1820C.

So from the silicon metal and methyl chloride we can start to build our silicone fluids using a method of synthesis called the ‘Rochow’ process.

The types of silicones coming from this process are the dimethicones, cyclomethicones and some silicone elastomers (formed by cross-linking).

Catalysts used to form the fluids are either acidic, alkali or peroxide based depending on the desired end result.

So is the article right?

Well yes on one level it is.

OK but are all silicones made like this?

Yes, all silicones start off this way but there is something in what is left out of this statement that is (unintentionally) misleading.  These basic silicone fluids can have functional groups added onto them to give them special powers!  Some have functional groups to help them stick to surfaces such as the hair (conditioning) or metal (polishes, lubricants etc).  Others are sticky and form adhesives and sealants while others can be designed to increase the SPF of a product.  The possibilities are endless really as outlined in this brochure.   These functional groups can be and are derived from a wide range of starting materials, some of which most probably include petroleum derivatives.

So is there a better way to sum up the origin of silicones?

In my opinion, based on the evidence outlined in the documentation above I would suggest that a more accurate description of the origin of silicones would be something like this:

Silicones, or polydimethylsiloxanes are a diverse family of  synthetic* chemical polymers based on silicon metal which is derived from sand.   

*Synthetic= not natural, not derived from renewable carbon.

It is my opinion that stating as fact that manufacturers and consumers mistakenly believe silicones are petroleum derived adds nothing to the article and indeed serves to confuse the reader.  Especially given the complexity of the reactions required to produce polydimethylsiloxane and the fact that the cosmetic industry uses a wide variety of silicones, many of which are modified and COULD be part-petroleum derived.   Lastly as the cosmetic industry has a vocal ‘free from petroleum derivatives’ marketing element to it I can see this statement as playing to that and potentially leading to brands using silicone derivatives in the mistaken belief that they are both petroleum derivative free AND therefore better for the environment than another option.

But silicones can be petroleum free is that not relevant?

I take the point that it is entirely likely that both the silicon metal as presented and the Methyl Chloride have come from non-petroleum sources BUT (and this is a big but) there is no denying the fact that both the silicon metal and the methyl chloride didn’t just drop from heaven in these usable forms and that their production WAS most likely thanks in part to the petrochemical industry.  I also feel that as the net result, the polydimethylsiloxane is unlike ANYTHING found in nature one can never push the ‘petrochemical free’ tag without it being misleading given that these days people often assume ‘petrochemical free’ to mean natural even though that logic is also flawed.

In summary what I’ve learned from this. 

In my job as a consultant chemist and help desk advisor I am asked all manor of questions from all manor of people. People who are often just starting out on their cosmetic journeys and have a real desire to understand the truth whatever that means.  Most haven’t been around long enough to hold any long-formed views or prejudice but nearly all are receptive to trigger words such as ‘natural’, ‘petroleum derivative free’,  ‘organic’,  ‘nasty’ etc.  I have been around a long time and can pick up on things that might ‘lead us down the garden path’ so to speak but that doesn’t mean I’m immune from wandering down that path myself as this exercise has taught me.  Before reading that article I did ‘believe’ that dimethicones were part petroleum derived because  I had never really looked at how these chemicals were made before and assumed the methyl groups (CH4) on the polymer backbone were of petroleum origin but I was wrong. However, my belief wasn’t so much of a formed and researched position, more of a natural assumption held tentatively until I had time to challenge it.  That said, I let my natural assumption guide me to the wrong answer on first evaluation.

It was only today when I had more time, more peace, more inclination to get to the bottom of this that I’ve gotten the truth.  The truth that I was wrong.  But on carrying out more reading I have come to the conclusion that it wasn’t just me that was wrong.  That all-important sentence that was highlighted at the beginning of the article in question was also wrong.  Not necessarily in what it said but in how it was said and the buttons that it triggered in the reader’s mind.  Now this may seem like me either trying desperately to clutch at straws and not be completely wrong but it isn’t so.  It is always an up-hill struggle to think things through.  It is mentally challenging, exhausting even to have to carry out research on every little word, to chunk down every little thing and to cross check process after process to really find out what happens.  I feel that in saying ‘manufacturers and consumers mistakenly believe…..’ our own ability to work things through is put into question.   Statements like this in an article quite literally turn the brain off – what’s the point, everyone makes this mistake so I may as well not think about it too much and just take what is said as true’.    While I didn’t immediately fall into the ‘well I’ll just believe you’ trap, I fell into the ‘well I believe that is wrong’ trap which is basically the other side of the same coin – I let my bias lead my response.

So what now?   Well now I feel lighter, enlightened even as not only do I now know where the carbon on a dimethicone comes from I also have a new appreciation for how important it is to step back and think, really think about what has been written before running off to answer what you assume has been said.

How very grateful I am!

Amanda x





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