Ask Dr. Pete: On Color Protecting Detergents & Reading Product Labels

Ask Dr. Pete: On Color Protecting Detergents & Reading Product Labels

A product inventor, innovator, and sustainability expert, he’s the brains behind our Bio Laundry Detergent and was a founding member of The Sustainability Consortium. Last month he covered everything you need to know about sanitizing and answered questions about seasonal skin irritation. This month he’s back with more helpful knowledge, including how to decipher what’s wrong (or not) with your shampoo’s ingredient list and the chemistry behind how color protecting detergents work. 

What is sodium methyl cocoyl taurate? Or sodium cocoyl Isethionate? They're in my shampoo but I don't know if they're bad or not. It claims to be a plant-derived shampoo.

Both sodium methyl cocoyl taurate (SMCT) and sodium cocoyl Isethionate are widely used as anionic surfactants in skin cleansers and hair shampoo formulas. SMCT and SCI provide a creamy, stable lather and are much less irritating to the skin compared to carboxylic fatty soap or sodium lauryl sulfate (SLS). 

SMCT and SCI molecules are partially bio-based – the hydrophobic “cocoyl” part is derived from coconut fatty acid. The hydrophilic parts of SMCT and SCI are derived from sodium isethionate and other synthetic chemicals. The origin of sodium isethionate, however, is somewhat problematic from both a safety and environmental standpoint, as it is produced from the chemical reactions between ethylene oxide, a carcinogen, and sodium bisulfite, an reactive compound that releases sulfur dioxide or absorbs oxygen.

In other words, while both SMCT and SCI are safer alternatives to SLS, use with caution. It is critical that strict and careful quality control needs to be applied during the manufacturing of SMCT and SCI. This is to ensure that the toxic reactants are totally eliminated, and no residues are left over in the finished products.

These ingredients are relatively stable in water at room temperatures, but outside the pH range of 5-8, SCI tends to hydrolyze in water and decompose at much faster speed. So, best practice would be to use your shampoo within its shelf life and avoid exposure to heated conditions in storage. 

Are there specific ingredients to look out for when it comes to caring for fabric colors and dyes?

In order to protect the color of laundry fibers, a good laundry detergent should be able to extend the life of clothing and linens through many cycles of washes and uses. To achieve this, a color protecting detergent has the following properties:

1. Does not contain organic solvents that tend to dissolve color pigments, such as propylene glycol (PG), polyethylene glycol and their derivatives.
2.  Inserts effective actions to prevent dissolved color pigments from redepositing onto laundry fibers during washing and rinsing.
3. Is made up of mild, bio-based ingredients with few toxic byproducts from harsh synthetic chemical reactions.
4. Is effective in removing the lint from laundry fibers during washing and rinsing.
5. Does not contain harsh surfactants and bleaches that tend to disintegrate the laundry fibers’ integrity over repeated wash cycles.
6. Has a pH close to neutral, e.g., between 7 and 8.5 as acidic or basic solutions tend to accelerate color fading.
7. Does not use optical brighteners, which tend to stick to the fabric fibers even after rinsing. Optical brighteners change the original fiber’s color to appear brighter, and they have raised some consumer concerns for skin sensitization.
8. Formulated to perform under cold water wash conditions, which are recommended for color preservation; cold water washes tend to dissolve fewer color pigments and preserve the color longer as compared to repeated hot water washes. 

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