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Blue to Clear Liquid Formulations
Here’s an example formulation of Duo Lash Glue “with vitamins”:
Acrylates/Ethylhexyl Arcylate Copolymer, Retinol, Ascorbic Acid, Tocopherol.
The liquid brushes on as an almost glowing light blue color. As it dries, the color fades and the final stage, it is dry and completely transparent.How?
There are no colorants.
Perhaps related - why do some sunscreens apply with a purple-white cast but dry down to transparent?
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8 Replies
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Here’s an alternate formula that I believe appeared glowing blue but turned transparent on dry down:
Acrylates/Ethylhexyl Acrylate Copolymer, Water (Eau, Aqua), Retinol, Ascorbic Acid, Tocopherol, Ceteareth-25, Propylene Glycol, PEG-60 Hydrogenated Castor Oil, Glycerin, PhenoxyethanolCould this more complicated list potentially result in the effect described?
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Microemulsions and suspensions of sub-micro particles often have a blue hue.
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Oh, interesting.
Is that also the reason sunscreen looks purple on deeper skin tones sometimes? -
Unlikely. I think that’s because sunscreen absorbs (and sometimes reflects/emits) certain wavelengths which changes the spectrum or rather has our brain interpret the colour we perceive differently. Pink is a colour which our brain ‘creates’, it’s not a real colour but interpreted due to a gap in the spectrum.
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Pharma said:Unlikely. I think that’s because sunscreen absorbs (and sometimes reflects/emits) certain wavelengths which changes the spectrum or rather has our brain interpret the colour we perceive differently. Pink is a colour which our brain ‘creates’, it’s not a real colour but interpreted due to a gap in the spectrum.
It could be though.
Blue = from ‘white’ sunscreen.
Red = from darker skin tones.
The sum of the above = purple.The majority of the absorption/reflection wavelengths for sunscreens is shorter than what the eye can see anyway, right? So I don’t understand why this would amend our perception.
For sunscreens that leave a white trace, it could either be the above (giving a purple effect) or the simple combination of white from particular ingredients (TiO2 or ZnO, especially if not micronised) plus darker skin tones (which could give the more ‘pink’ attributes as you mentioned). -
You’re thinking RGB. The perceived colour space is more than that.A citation form THIS article (one of many) gives you an idea (if you don’t want to read the whole article): Notice, however, how many of these colors, including cyan, brown and
magenta as well as pink, do not exist on the visible spectrum, yet we
perceive them as distinct. It is for this reason that some have opined
that color perception is “not actually a property of light or of objects that reflect light [but rather] is a sensation that arises within the brain.”Another example is a picture of THE DRESS which went viral. I, like many others, perceive it as white and gold, although it’s actually black and blue. We still don’t know why half the people see it this way and the other half that way.And then, unlikely with cosmetics, there are also impossible colours or colours which aren’t colours because there is virtually no light to see such as Vantablack. Back to (off-)topic: the Tyndall effect and other similar effects (for example Quantum dots) are not based on absorption/emission due to chromophores but other causes of interaction with light waves.Bottom line is: I don’t really know why sunscreen looks purple on darker skin. I’m simply guessing. You’re right, sunscreen does mostly absorb invisible UV light but not just that. Also, UV light is absorbed and then emitted at longer wavelengths by quite a few materials and thereby changes colour perception of the surrounding colour. This is how optical brighteners in laundry detergents work.
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I suspect the adhesive polymer (which matches INCI name with Daitosol 4000SJT) shows some slight fluorescence in solution, and the effect decreases as the product dries and the water evaporatesnot having seen the product or the polymer in question, this is pure speculation
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