Why is Sodium Hydroxide (lye) Not Listed as an Ingredient in Soap in T - The Soap Coach
Why is Sodium Hydroxide (lye) Not Listed as an Ingredient in Soap in The UK?

Why is sodium hydroxide aka lye, not listed on soap labels within the UK?

Why is glycerin on a soap label if it is not one of the original ingredients? 

 I often get asked about the labelling requirements for soap here in the UK and although it is a simple subject it can be a little bit confusing initially.

Anyone who has made soap will know that we use sodium hydroxide in our recipe, indeed it's not possible to make soap without it, however you will never see this ingredient listed on the label of a bar that is compliant with the legislation within the UK .

Why? To answer this question we need to go back to the science side of things and I will do my best to keep it simple.

Soap making is a form of chemistry,   Sodium hydroxide has the chemical symbols of Na for sodium and OH for hydroxide and quite simply, when this is mixed with water and oils a chemical reaction (saponification)  happens and you are left with soap which is a completely different compound. 

It is easier if we look at an example.  In my basic soap recipe I use coconut oil, olive oil and cocoa butter , water and sodium hydroxide. On my soap labels however you will see Sodium Cocoate, Sodium Olivate, and Sodium Cocobutterate plus Aqua and Glycerin, not necessarily in that order and then whatever colours or fragrances  I have used plus any allergens which must be listed if they are present at more than 0.01%. 

There is no Sodium Hydroxide listed because there is none in the finished product. When a soap recipe is assessed by a cosmetic chemist for safety (as it should be here in the UK prior to selling ) your chemist gives you a breakdown of what your finished soap consists of and the exact %.of each ingredient. This ensures that you label your product correctly. Glycerin is included as it is created during the saponification process and in quite a significant quantities. 9% of my soap is glycerine.  

In my view it is still not quite correct as there is a small % of butters and oils that are left unsaponified (your superfat) and these are not listed on the label but it would seem that this is how we do things in the UK and that is not something I have any control over. 

On that point, looking at the label is a really good way of gauging whether a soap maker is compliant with the cosmetic regulations here as if the labelling is not correct they may not have done their research in all the relevant areas.

You can also get a good idea of what the original ingredients were as many of the Saponified oils  will be recognizable in one form or another.  If the soap label contains lots of ingredients that you cannot recognize there is every chance it is a commercial bar and not quite what it seems on the surface.

If you are struggling with the regulations for selling soap and skincare products and compliance in general for the UK do take a look at my Soap Business Boot Campwhich will save you a great deal of time, effort and worry plus you will have access to me in a private Facebook group for support along the way.

Comments (2 Responses)

14 August, 2023

Keri @ The Soap Coach

Hi Nick, that is a really great question and having reread the blog I don’t think I have explained it very well so I have tweaked it now, but the bottom line is there is no Sodium Hydroxide in the soap by the time it has become ‘soap’. It has all be converted in to something else, namely Sodium Olivate etc – I hope that clarifies it for you

14 August, 2023

Nick Askham

Hi Keri – I’ve read your blog on this subject several times and struggle to see any logical reason why lye is not shown on labels. The very fact that a by product is included whereas the main one isn’t clearly doesn’t make sense. I would suggest that the reason for its exclusion is emotive just as the inclusion of glycerine is also. Please let me explain: glycerine has a “good press” whereas sodium hydroxide does not. Further, your inclusion about other ingredients shown on some soap seller’s labels is hardly pertinent to this thorny issue. In short I would say that people wouldn’t like to read, and certainly don’t like to think that their lovely soap contains the nasty sodium hydroxide but does have the nice glycerine included. Just my point of view on the subject. Regards Nick.

Leave a comment (all fields required)

Comments will be approved before showing up.