Wavelengths of light, and respective degredation...

Say a bit more, Dullah. Is the question whether perfume stored in partial shade but not in complete darkness will still be damaged? If that's the drift of your question, I'm very interested, too.

Now, THAT's a question... basically he is asking which color of light affects perfumes the most.
Since it is common knowledge that "heat" (infrared light) is not as dangerous as daylight, I'd say, high frequencies (short wavelenghts) are the worst...
I would believe that Ultraviolet light is the most dangerous for perfumes as it is also the most dangerous for organic materials and it has the higest energy content. Now I am not chemist or anything... But that is my guess.

You could search for Photo-chemical Reactions and Degradation by Ultraviolet light or Infrared light. If oils, organic compounds like aldehydes and alcohol are sensitive to that kind of light... well there is your answer.

I learned physics in University (esp. Quantum Physics), but my English is not so good...
I`ll try anyway.

Let`s say that any molecule perfume consist of has its own characteristic frequencies. It`s like balls connected with springs - different mass of balls and elasticity of springs results to different frequencies. And every connection has its own frequency of oscillation (well, there`re compression-extension frequency, rotation frequency, etc).
The more complex is molecule - the more frequencies it has.
Then - every modern scent consist of tens and hundreds of molecules. Naturals gives us up to 300-500 components with their own frequencies.

When the light hits the molecule, it absorb a quantum of specified energy and frequency and oscillates faster. It could then goes two ways - 1) the spring broke down and molecule become two (smell differs); 2) molecule emits energy by quantum of the same (or lower because of friction and dissipation, so temperature of perfume is going higher) energy.

How to determine the most harmful spectrum for perfumes?
It`s not the one coloured rays - but the broad spectrum. White light has the most broad spectrum, from unfrared to ultraviolet (UV does not counts, as flacons are made from glass which blocks UV almost 100%), so it does more harm to perfume.

By the way - infrared light is harmful too, as it does heaten up a perfume, and glass does not block it.

Sorry for any mistakes (and for my school-like description too) - Luca Turin described the mechanism very good in his first book.
If by any chance you found the book like Popular Spectroscopie (or smth like that) - you`ll found the answer
sunlight

Two things to add:
sunlight has almost equal high intensity from 410 to 810 nm (InfraRed to UltraViolet).
any liquid do absorb all the light quantums except the colour it has.

I believe that there`s a reference-book of absorption spectrum for every aroma-chemical (lactones, aldehydes, terpenes, esters, patented synthetic molecules, etc.), so it could be easily found in physics or chemistry library (for patented - in those Givaudan, Takasago, etc).
But what is not so easy to found - the light-stability tables, to see the dependence of smell versus intensity and wavelenght of light and time.

Though I`m sure that it should have an exponential rate in time - but the smell is integrated and highly personal thing, so if molecule A under the sunlight becomes molecule B with different smell, it is still tricky to say when smell A will be disappeared fully, and what will be the smell of mixture of smells A and B.

I believe that nobody cares about it. Spoiled perfume is just perfume with more or less different scent, that`s it. And the only advice could be - make your perfumes to avoid the direct sunlight.

Let me start by saying that the previous answers are very good. I agree with what they've said. Irish has a good summary of the overall, and moon_fish is showing the theory behind what I've got for you. And Dimitrios has the real answer (see PS at end...)

I actually studied with a photochemist. I had this huge-ass answer that I was going to post, but I think I'm going to put it on my blog tomorrow instead. I mean, it was like three pages or something. Ridiculous! But this is a really cool question.

PS Dimitrios - 100% agreement there. Nothing like testing fragrances in the moonlight with a beautiful assistant. Speaking of which..... g'nite all!

I used to think light doesnt do anything to frags - then I bought the 2007 L'eau d'Issey, which had been left out of a box sitting in a shop window for god knows how long. It literally dissapeared after 10 mins - with a very, very slight 'lemon pledge' smell to it. The same frag I tested in Myers was strong for at least an hour. I took it back and changed it for Live Jazz & XS.
After this, I keep all my frags in a cupboard.

Hmmm.. I am not convinced... we need to do some testin'

Me and the beautiful assitant A couple of unbiased researchers will volunteer to test the effects of Light on fragrances...
they will need some Basenoters to donate some EDTs, preferably:
-Bottles of Le Labo Rose 31 or vanilla 44 (no it wont work with another Le labo fragrance)
-Vintage, Ultra hard to find fragrances.
-All Natural Perfumes.

Something tells me a full bottle of Angeliques sous La pluie will also be needed. I just finished my decant, otherwise I would gladly donate it. PM me so I can send you the address of my home an independent and serious lab.

We all have to do sacrifices in the name of science.

I have the same ... errrr ... affliction as Redneck Perfumisto. My physics dissertation focussed on calculating the quantum scattering cross sections of electrons crashing into atoms. And as I'm sure Redneck would be happy to tell you, those calculations are very similar to those of light scattering from molecules. However, all physics ever delivered to me was gray hair and a cynical nature that it has taken years to get under control. Knowing what happens when different energies of electrons hit atoms has only provided me a periodic "Oooo, impressive ..." during job interviews. That, and $4.50 gets me a latte. Here's all you really need to know:

Keep your fragrances in an opaque container as cold as they will tolerate without causing the component oils to congeal and turn the fragrance into a heterogeneous mess. Take a small amount out occasionally and put it in a small atomizer for daily/weekly use. Repeat.

If you're still really afraid of light killing it, perform this whole operation in the dark while wearing an aluminum suit to stop the infrared radiation from your overly excited body from exciting vibrational modes of the molecular bonds in the essential oils ... and take pictures (with no flash). I want to see if you really do this. Spend less time obsessing about wavelengths and go "catch a wave" down at one of those awesome beaches you folks have in Southwestern Turkey. There's a reason the German tourists love it down there so much. Go discover it ... and wear your best oud.

I'm having a moment over here, getting all weepy ...

Moonlight is what is referred to as "coherent light", reflected from a single source, the sun.

Interesting read is by Lawrence Blair. His Rhythms of Vision has a section on speculation that coherent light can actually bend straight the chaotic individual atomic structure of the edge of a dulled razor blade, thus 're-sharpening' it to some extent.

My area is optics (a specialty area of physics which concerns the behavior of light). And in my previous life, I also studied and practiced art conservation.

I agree with the explanations and suggestions made here--light and heat will degrade the materials in perfumes (and paint pigments, etc.). Many atoms/molecules fluoresce, and this process will eventually cause "bleaching" of the component which was activated by the specific frequency. I would also say that the incorrect humidity and oxidation are also factors, but in a sealed perfume bottle, this is less of an issue (unless it has a lot of air space inside which is taken in from the spray nozzle during use).

I would like to add one thing to the discussion about the EM spectrum:

MOST glasses do not transmit appreciably in the UV spectrum, but they do transmit in the visible and near infrared to a great degree. Plastics transmit very broad band, including UV.

But the sun is a broadband source and the moon essentially scatters the photons...so this is not really a coherent source. However, if you are talking about stars--while they are also broadband, in an optical system, they behave similarly to laser light when viewed. This is due to their great distance more than anything. In essence they are point sources.

Coherence is a very complicated concept--one of the icons in the field is Emil Wolf, although his work is not great for bed-time reading

Well, I did a lot of looking, and couldn't find much info about specific chemistry of perfume decomposition. Only two things. (Just to explain why I didn't find more of this stuff - I can't use my usual sources, since this ain't work-related).

I found one case where a natural frag chemical (guaiazulene, in blue chamomile) in a sunscreen was exposed to artificial sunlight for 3 hours (including both UVA and UVB), and the content of guaiazulene in the sunscreen was reduced to only 21% of the original amount! Meaning almost 80% was destroyed in just 3 hours of direct sun, even in the presence of UV-absorbing substances, and boo-koo of them. Ouch!

The other thing I found is actually very helpful, but it's not about frags, per se. It's about the fragrance of beer (sorry about that, Dullah, but beer does appear to be useful for something - in this case helping us to understand frags! ). I turns out that the chemistry of "skunky" beer has been a mystery for many years, but the final answer wasn't found until fairly recently. I won't get too deep in the chemistry, because it's pretty complicated. But the lowdown is that:

1) Skunky beer comes from small amounts of sulfur-containing compounds which are formed due to light exposure.

2) It happens due to visible light, not UV.

3) It happens with clear or even green glass, but is diminished by amber glass.

4) The basic mechanism is that a substance other than the fragrance chemicals themselves absorbs the light, and that substance is the bad actor that starts everything. The fragrance chemicals are never themselves electronically excited by the light, which in their case would have to be UV. In the case of beer, the bad actor is riboflavin.

5) The substance that does absorb the (visible) light then steals an electron from the fragrance chemicals, and that starts a path which not only eats up the fragrance chemical, but also creates a new, stinky one.

6) The implications for frags are: (a) glass can mostly stop UV, but your frags are still at risk for sunlight damage by visible light, unless they are in dark or opaque glass (as Astaroth said). (b) although UV normally does more damage per photon, it is the specific frequency activating whatever bad stuff is actually possible that is the most dangerous, and (c) whatever happens depends markedly on the total mix of substances which are present in the juice, and what bad things are possible given that mix.

But in any case, I would agree that we have to be careful not to get too retentive about our frags. Cool and dark is good, the more, the better, but not so much that it gets in the way of enjoying your frags. Which is why Luca Turin apparently just sticks his on a shelf where he can see them!

Now, still, I do like Irish's suggestion about actually demonstrating what can happen (even if he was only trying to scam us out of our good stuff! ), so I'd like to do some kind of home experimentation, sorta like a Great Internet Perfume Skank-Off. We can get pictures and scent reports on pairs (or greater) of vials, one a control, and the other(s) subjected to various skank-inducing conditions. Not exactly hardcore science, but we can't exactly afford to buy a GC-MS on Grant's spare server change. Still we can do some simple bathroom science that's kinda fun, and will definitely give us a feeling for the magnitude of this thing.

So what I'm saying is that we should stop simply whining about those frags we don't like, and actually get a bit medieval on 'em! Whaddaya say, people? <evil scientist laughter>Bwah-ha-ha-ha-ha!</evil scientist laughter>. Who's with me? <signature revoked below/>

The easiest way to stop all light from hitting your fragrances is to wrap them in metal foil, which prevents transmission of infrared, visible, and ultraviolet light. (It's nice that the Fermi Sea is really there when you need it. ) If you really want to still be able to look at your bottles, take a high resolution photo of them and paste it on the outside of the foil container (sort of like those screensavers of fish swimming in an aquarium).

Great post, RedneckPerfumisto. Something similar happens in paper--light, moisture, atmopheric acids and heat activate lignin contained inside the paper (paper is formed by cellulose pulp, often wood). The lignin reacts with the environmental factors and causes the hydrogen bonds in the paper structure to break down, making the sheet much more brittle. It also turns the paper yellow-brown due to Sulfur content of the acidic contaminant.

I suppose this is why perfumes with more naturals go bad relatively easily--they have more impurities which degrade the scent when they recombine to form new molecules.

How did you find out that aromachemicals respond mostly to UV? I have seen research about painting pigments and dyes that fluoresce, but I think the activation spectrum band varies based on the substance.

This may be the answer to the "Creed Lot Number" question that I posted earlier. Naturals degrade faster, in the bottle and on the skin, due to their unstable nature/impurities. Sounds reasonable.

Actually, that's just my own conclusion based on two unrelated observations. (1) I now have several books on aroma chemicals, plus my previous books on common organics, which included aroma chemicals. It turns out that the vast majority of these are either benzenoid aromatics or aliphatics with minimal unsaturation - typically one isolated or two conjugated double bonds, maximum. Consistent with this, they're almost all colorless solids or liquids, clearly absorbing very little in the visible region. (2) Most of my work was with things which did absorb in the visble region, and which have higher levels of conjugation. Generally speaking, even these absorbed mostly in the UV. But their lowest energy transitions were clearly tailed into the visible. We studied the electronic transitions of these puppies, and I had to do a bunch of calculations. Anyway, based on the structures of the aroma chems in my books, they should have their lowest electronic transitions in the UV. It's only the more highly conjugated ones that should have transitions in the visible. And, I should add, most fragrance chems are (in a structural sense) very similar to the ones that give beer its flavor. These were noted specifically by the authors as not having transitions in the visible region, which is part of what made it all a mystery. It wasn't until the role of riboflavin was postulated that things started to make sense in the case of beer photodecomposition.

Yes, it makes sense. Most natural oils that we were using in our recent project clearly have components absorbing in the visible region. Larger samples that I have ordered or looked at online are almost always shipped in amber glass, and the really big ones come in aluminum bottles. Such oils have an excellent chance of introducing one or more substances, absorbing in the visible region, which are capable of electron transfers, photooxidations, etc., after absorption. I would expect that the darker the natural oils and the lighter the glass, the more at risk the fragrance is.

It's great when science works!

I'm too lazy to get out my photochemistry text, but here's my 2c worth:

Short wavelength/high frequency EM radiation such as UV has sufficient energy to create free radicals, which are highly reactive chemical species. These can then attack other molecules, living or dead (I'll get to that in a second), causing chemical decomposition to occur. I presume the free radical can also be formed from the fragrance molecule itself, in which case it might break apart on its own or react with something else, but more likey the radical is formed from oxygen present in the bottle or from ethanol, which is the major constituent in perfume. Radicals are implicated in causing cancer, aging of skin, and other nasty things. Many perfume molecules, especially natural products, are big, hetero-functional molecules that are highly susceptible to attack by free radicals, so it's not surprising that light would cause damage, even if only a few percent of incoming UV radiation were to pass through the glass.

p.s. Moonlight is NOT coherent. Coherency is a specific term used in laser optics to define light in which the peaks and valleys of the light waves are oriented the same way in space (all the waves "rise and fall" at the same time, to put it simplistically). As said before, moonlight is merely reflected white light. [Later: disregard what I wrote about coherence. Upon further checking, I realize there's more to the subject than I thought. However, I'm still pretty sure that moonlight is not coherent...]

Snafoo, you are right--the application to lasers is only one part of coherence. It is possible to have coherent behavior in an optical system with white light, but specific conditions in the optical design must be present. Also, coherence has both spatial and temporal components. With the white light coherent system, the spatial portion is what is important as there is a "coherence volume" within which the light has coherent behavior. Also, as I previously mentioned, the "point source" quality of distant stars is a special situation that causes some optical effects which we also see with coherent light sources.

It can be confusing even to me, and it is part of my background!

Anyway, lasers are also interesting, and the light has characteristics other than coherence that make it special. These include directionality and monochromaticity.

Sorry, OT

I can provide one data point here. I have a 125ml bottle of Polo Sport that apparently rolled under the seat of my car at some point last summer. It got stuck under there for almost a week, getting pushed up to 100 degF pretty frequently since my car was being parked in one of the hottest parts of the San Fernando Valley.

I am still using the bottle today, and the week of baking it experienced last summer does not seem to have impacted the fragrance at all. It still has all its longevity too. I was all set to toss it out and buy a new bottle, but I didn't need to.

Huh? Why be so pedantic?

Why, because we're pedantophiles, of course!

"Wavelengths of light, and respective degredation"...

"That is just the sort of pendatry up with which I shall not put!"

I humbly bow to those with higher learning arcs when it comes to light and wavelengths :wave: and such photonish things . I shall write Mr. Lawrence Blair a scathing letter admonishing him to lighten up in his next tome.

I'll participate in any thread involving degradation, respective or not.

Pedantic? I thought we were having a light discussion...

LOL

KBE, I am not sure about the author you refer to--perhaps he is a dedicated and serious scientist. Or, maybe he is an imaginative sort, but I think that is very enjoyable also. Pop-science or serious-science aside, I sure do miss the days when I could watch Star Trek and accept most of the tech-babble....

The CRC Handbook of Chemistry and Physics has many tables of absorbtion data but it is rather technical, and a good background in chemistry or physics is handy to get the most from this text. The Merck Index also has good information, that is a little less technical, plus it has an index of common names of many chemicals.

Overall though moon_fish's answer is a good summation. Each compound will react to light differently due to things like type of molecule, the types of bonds, the bond angle, and other intra and intermolecular factors will cause each compound to react in a certain manner so there is no one answer to your question.

Very interesting! It does seem that well-sealed bottles do nicely against that level of heat for many frags. I think it's poorly sealed bottles that get baked hard in the trunks of black cars and the like which tend to suffer noticeably. Your experience is consistent with Luca Turin's 90:10 light/heat frag danger estimate.


LMPAO! And, of course, because we're not evil! (Well, at least not always...)


You mean we're not talking about bad Milla Jovovich movies, political extremists, and sexual B&D? Crap! I'm on the wrong thread!


Good Lord. As long as it took me to get that, I think the free radicals must have destroyed my brain. Time for more red wine antioxidants.


Yes, but those were the days that made us fall in love with science. It took me the rest of my life to realize that art is just as important, if not more so, and not to be so hard on the babble. Hard science boxes under the curvature of the universe and includes too little. Soft science and art box around it and include too much. We all seek to describe the same beauty.


...so there is no one answer to your question.

The discussion begins as one point, expands in many beautiful ways, and returns to a single point of truth. Every fragrance is its own story. Even when it dies.

Now, where was I? Oh, yes. Bought Armani Code today. In the opaque black bottle!

Would the smell of a fragrance change if left in the hot summer sun for a few days,

Great research, Redneck!
I always believe that in perfume spoiling should be some other agents not only perfume molecules.
So - dyes also includes some kind of degradation, that`s for sure.
And it makes sense that modern perfumes has less golden-brown colours than all the vintage juices were.

I`d suggest that chemistry chefs in perfume labs do know the weakest link in the chain. But never tells you what it is in particular perfume made in their lab.

Also it`s doubtful that aromachemicals has mainly UV-spectrum of absorption - just the fact they are translucent does not prove it. It could be also invisible infrared spectrum (rotational spectrums are IR spectrums - when photons brings energy enough to rotate the molecule. It`s the easiest way to move molecule, next is oscillatory movement).

UV spectrum of absorption gives us another mechanism of absorption, when photon energy is big enough to separate the weakest electron from molecule. And that`s about free radicals and it`s the worst way to spoil perfume (except dirty fingers in perfume bottle or dilution with whatever you find out on kitchen).


`I suppose this is why perfumes with more naturals go bad relatively easily--they have more impurities which degrade the scent when they recombine to form new molecules`.
Asha,
I believe that those `impurities` are the best part of naturals, and they gives natural oils the most sought after quality. So let`s put it like - They have more beautiful chemical components comparing to synthetics, and therefore they have more chances to be spoiled by light and spoil all the perfume.

Also,
it`s great to find out so many colleagues!!!

Great research, Redneck!
I always believe that in perfume spoiling should be some other agents not only perfume molecules.
So - dyes also includes some kind of degradation, that`s for sure.
And it makes sense that modern perfumes has less golden-brown colours than all the vintage juices were.

I`d suggest that chemistry chefs in perfume labs do know the weakest link in the chain. But never tells you what it is in particular perfume made in their lab.

Also it`s doubtful that aromachemicals has mainly UV-spectrum of absorption - just the fact they are translucent does not prove it. It could be also invisible infrared spectrum (rotational spectrums are IR spectrums - when photons brings energy enough to rotate the molecule. It`s the easiest way to move molecule, next is oscillatory movement).

UV spectrum of absorption gives us another mechanism of absorption, when photon energy is big enough to separate the weakest electron from molecule. And that`s about free radicals and it`s the worst way to spoil perfume (except dirty fingers in perfume bottle or dilution with whatever you find out on kitchen).


`I suppose this is why perfumes with more naturals go bad relatively easily--they have more impurities which degrade the scent when they recombine to form new molecules`.
Asha,
I believe that those `impurities` are the best part of naturals, and they gives natural oils the most sought after quality. So let`s put it like - They have more beautiful chemical components comparing to synthetics, and therefore they have more chances to be spoiled by light and spoil all the perfume.

Also,
it`s great to find out so many colleagues!!!

You're right about IR - both UV and IR are always strong for organics. The fact that these can be used to fingerprint a substance pretty much depend on it. It's just that you have to get pretty short in the UV to get to where things like alkanes start absorbing, and when you get out there, it's like Snafoo was saying - all kinds of bad things start happening. Any UV that gets through your glass is going to cause trouble. There's almost no way around that. I have some CK Crave in a plastic bottle, and am very curious if it's at risk for UV, or if the plastic was treated to prevent UV transmission. The fragrance smells bad to most people anyway, so not sure if that's much of a test!


LOL - that's right! Nothing like human oils or isopropyl alcohol to ruin a perfume!


Absolutely! Although the best science thread ever on this board had to be the Schroedinger's Frag thread, a.k.a., Should I open the box?

Some of the impurities found in natural fragrances add nothing to the scent; things like the waxes, fatty acids and their esters are carried into the essential oil in the extraction process. These compounds can go rancid quite quickly. But you are right in that a natural essential oil will be more complex and more pleasing to the nose of most people than a synthetic approximation of the same oil.

YSL Pour Homme is the only fragrance that I've ever experienced a rancid bottle of. The bottle is clear, perhaps it was light degradation.

I think most non-reactive plastic containers are polypropylene or polyethylene. Polyester, polycarbonate, acrylic are all great, but I don't see many non-reactive (ie, FDA approved) containers for cosmetics in these materials.

At any rate, plastic is typically coated if it is to filter UV--the ones I have seen (usually acrylic sheeting or tubing used to filter UV from artwork). This coating has a yellowish cast to it, and chances are it is not non-reactive when in contact with liquids and gels. I am sure it is also very expensive.

When I go to work tomorrow, and if I remember, I'll see if my optical materials catalog has transmission data for plastics. Of course, no plastic atomizers will be made from optical grade plastics (way too expensive), but it is worth it to see how far down they actually go to the UV.

Most glasses that pass visible light will also pass light from the near infrared, up to around 2 micron wavelength.

Anyway, I'll see what I can come up with!

Ok, I checked data for plastic, and it is not very complete. As a baseline, a typical borosilicate glass (BK7 from Schott) will transmit 99% from 1530 nm to 365 nm. It falls off rapidly in the UV region, and more slowly in the IR region.

The plastic data I have is far less extensive, and the catalog says that acrylic and polycarbonate are designed for the range 1014 to 365 nm. It does not show me how rapidly the transmission falls off at the two ends.

365 nm is indeed UV, but is considered "near UV". So, this region consists of SOME damaging UV, but other parts of the UV spectrum are blocked significantly, at least with the glass. Data on the plastic is inconclusive.

Thanks, Asha. Here is some more info for you. I checked my bottle of Crave - it has 3 separate layers. The outer clam-shell container is type 5 (PP). The bottle that you hold in your hand is type 7 (other). The inner bottle holding the juice itself is not labeled at all, but appears to match the type 7 plastic around it.

I decided to dig through some of my books, and I found a few interesting paragraphs.

Here is a quote from one of my books, The Chemistry of Fragrances, referring to an exemplary formulation:

"The formulation also contains an ultraviolet (UV) radiation absorber, benzophenone-2 [0.50% w/w in final fragrance containing 78% alcohol and 12% fragrance; author note: Uvinul D50® ex BASF AG], to prevent degradation of the fragrance and any dyes by light. Although consumers are encouraged to keep fine fragrances in the dark, the manufacturer needs to protect the product from those customers who insist on storing it on a sunny windowsill!" (exclamation is original)

There is more in the way of general statements later:

"Light stability, even though a UV absorber is being used, must also be checked to ensure that the fragrance does not darken unacceptably or that any dyes added do not fade. It may be that, in this case, a different UV absorber works better or that the perfumer needs to change one or two of the ingredients in the fragrance."

There is also a nice description of a hypothetical perfume heat/light stability test - probably representative of reality. I will post that in another post shortly, to keep the length of this post down (and to get a little shut-eye, as well!)