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Shampoo Bar Turning Pink
I’m formulating a shampoo bar and for some reason it’s going from white to pink with in a week or so (faster if placed in a 50C chamber). Let me know if you need me to put the percentages. Any help would be appreciated!
Here is the formula:
ucuuba butter
octyldodecanol
sodium lauryl sulfoacetate
sodium cocoyl isethionate
manuka honey
ketoconazole
geogard ECT
panthenol
sodium citrate
caffeine
tocopheryl acetate
citric acid
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12 Replies
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I manufactured shampoo bars between 2006 and 2024. And I kept it simple……first, absolutely zero synthics, and secondly, I used the traditional saponified soap bar approach. Was never any issues, and the bars sold well globally. I also produced Private Label bars for a few brands globally, including Japan.
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Sometimes a pink discoloration is caused by bacterial contamination or by some fragrances discoloring. It could also be caused by a reaction between some of your ingredients.
It is possible that you have bacterial contamination due to the honey.
You could try a knock out experiment to see if one of your additives is causing the issue.
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Thanks I’ll try that!
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May be associated with sorbic acid stability. As ozgirl suggested, try a knockout protocol.
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Separately and forgive me for changing the subject - this appears to be a drug product in US regulatory context. Assume you’re not selling in US.
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I’m formulating this for a brand and they will decide where they are selling it and what steps need to be taken once we have a stable product. That is all I can say.
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ucuuba butter Highly unlikely
octyldodecanol Unsure what this is
sodium lauryl sulfoacetate Highly unlikely
sodium cocoyl isethionate Highly unlikely
manuka honey Try without
ketoconazole I use an rx shampoo, its orange but has coloring in it, not sure if it could be pink
geogard ECT Highly unlikely
panthenol Highly unlikely
sodium citrate Unlikely
caffeine Unlikely
tocopheryl acetate Highly unlikely
citric acid Unlikely
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Just for fun, I’ve asked chatgpt, and surprisingly (to me), the answer makes sense:
Most Likely Causes of Pink Discoloration:
1. Geogard ECT
INCI: Benzyl Alcohol, Salicylic Acid, Glycerin, Sorbic Acid
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Why: This is a broad-spectrum preservative that is well known to sometimes cause pink, red, or orange discoloration in formulations — especially in alkaline or moisture-prone environments, or when interacting with metal ions or certain surfactants.
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Mechanism: The sorbic acid in it can undergo oxidation or microbial degradation, especially when pH is not sufficiently low (ideally below 5.5), leading to color changes.
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Why: This antifungal active is typically a white to off-white powder, but can discolor in the presence of certain surfactants, preservatives, or pH shifts. There have been rare reports of it contributing to color shifts in formulations, especially when not fully solubilized or evenly dispersed.
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While honey is usually amber to golden, in combination with heat or certain preservatives, it can sometimes darken or react, though pink is not the usual result.
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Generally colorless to pale yellow, but can oxidize over time, especially with exposure to heat, light, or metal ions, potentially interacting with other ingredients.
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Usually used as pH adjusters. Not direct causes, but can shift the pH, affecting the behavior of color-reactive ingredients like Geogard ECT.
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Storage Conditions:
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Heat, humidity, or light can accelerate discoloration reactions.
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Metal Contamination: From manufacturing equipment, containers, or water can catalyze discoloration (especially iron, copper).
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Microbial Growth: If preservation is not strong enough, microbial contamination can cause pink/reddish growth — though Geogard ECT typically handles this unless underdosed or pH is off.
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Suggested Next Steps:
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Check pH — keep it below 5.5 if using Geogard ECT.
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Remove Geogard ECT in a test batch to see if the pinking stops.
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Protect from light and air — store in opaque, airtight containers.
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Use chelating agents (e.g., disodium EDTA) to bind metal ions.
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Evaluate raw materials (especially honey and ketoconazole) for any color or odor changes.
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This reply was modified 1 month, 3 weeks ago by Aniela.
2. Ketoconazole
Possible but Less Likely Contributors:
3. Manuka Honey
4. Tocopheryl Acetate (Vitamin E)
5. Citric Acid / Sodium Citrate
Other Factors to Consider:
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Good point but Geogard ECT is not broad spectrum - nominally a Gram negative gap. Have to wonder at Aw - and if you need a preservative.
However, discoloration develops at 50C - not likely a biological event.
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Hi Phil,
I only said it makes sense, I didn’t say everything it’s true????
I know that Geogard ECT is not broad spectrum, I guess it’s my fault that I left the whole answer given by chatgpt.
Still, I was surprised, as I was expecting a colossally-wrong answer.
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Hi, your product is contaminated by the G- bacteria Serratia marcescens.
‼️So you have contamination in your: laboratory or on your utensils / lab equip or in your products - or in all three.
Very common in bathrooms, you’ll see it in fatty soap, or on grout or bathroom shower tiles, for example.
It is pretty pink to melon-orange pinkish.
Very pesky to eliminate.
S. marcesens is also considered a hospital acquired infection. [HIA]
So you absolutely must ensure you entirely eliminate this bacterial contamination. Like completely.
You really need to be diligent to see WHERE this is sourcing from, and to ensure you entirely eliminate it before you commence any further formulating.
But I am 100% positive – this is Serratia marcescens bacterial contamination.
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I did the knockout protocol and it turns out that it was the ketoconazole reacting with the surfactants resulting in a dark pink color over time. But your thoughts are interesting and will keep them in mind if something like that happens in a future formulation.
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