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FINALLY: a more direct test of the "feedback theory".


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#21 Clearly Smooth

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Posted 24 January 2006 - 09:21 AM

QUOTE(L8302 @ Jan 24 2006, 01:30 AM) View Post

You have NOT proven, as you claim, that there is no significant difference between sebum production DURING periods of intense washing and periods of no washing. All you have proven is that the skin bounces back from being stripped/de-fatted/cleaned at the same rate whenever you use the same product/method (Ivory soap and alcohol).

For comparison, imagine you want to test soil water evaporation rates in cloudy v. sunny weather conditions. After a week of cloudy weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. After a week of sunny weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. SURPRISE, it's the same! In this circumstance you have failed to measure the rate of evaporation DURING the respective weather conditions by levelling the playing field during actual analysis. That the soil is dryer or wetter at the time of analysis doesn't affect the rate of evaporation given the exact same testing conditions.

Do you see what I'm saying?


Your gentlelady,
~L


I see what you are saying. In my opinion, you make a very good point. However, I do agree with Bryan that oil is produced at the same rate, regardless of how often the face is cleansed.


#22 Daz!

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Posted 24 January 2006 - 10:06 AM

Well according to you feedback theroists then if you don't wash your face it'll be less oily and in fact feedback to the point where you will hardly produce any oil.
Hey that's great, so don't wash ever again and you'll get the affects of Accutane.
So I guess you guys don't ever wash your face and are clear of acne with beautiful oil free skin?
The truth is you are ignorant and illogical, you can't comprehend statistics which has saved the lives of so many people. You'd get into a fight with The Count on Sesame Street about mathematics!
Bryan well done, but I and logical others didn't need convincing, pubmed has all the info I need.

I think you should get Dan to put this in his myths section Bryan, backed up with Kligman references.
So that you don't have to continually educate people new to this site on this important point.
Many people wrongly fear using cleansers as they think it will produce more oil making acne worse.

#23 L8302

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Posted 24 January 2006 - 10:51 AM

Daz, I think you should review what I was saying. Effectively what was tested was sebum production after two instances of the same cleansing method, not the sebum production rate during the testing weeks.

The problem is with the testing method, not necessarily the conclusion.

Bryan has demonstrated that the sebum production is the same whether (a) you wash with Ivory soap and swab with alcohol or (b) you wash with Ivory soap and swab with alcohol.

QUOTE(Daz! @ Jan 24 2006, 07:20 AM) View Post

"You have NOT proven, as you claim, that there is no significant difference between sebum production DURING periods of intense washing and periods of no washing. All you have proven is that the skin bounces back from being stripped/de-fatted/cleaned at the same rate whenever you use the same product/method (Ivory soap and alcohol)."
Errr no.
The sebutape shows statistically the same sebum production rate, so no bounce back!

"I think we should all try and bitch less and be more constructive with out criticisms of the experiment, more in the manner of authentic lab researchers."

Sorry, the lab in the muppet show is not how things are done in the real world guys?


BTW This may come as a shock.... The world is not flat.
Feel free to discuss and flame me on that!



#24 Daz!

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Posted 24 January 2006 - 11:03 AM

QUOTE(L8302 @ Jan 24 2006, 09:51 AM) View Post

The problem is with the testing method, not necessarily the conclusion.

Bryan has demonstrated that the sebum production is the same whether (a) you wash with Ivory soap and swab with alcohol or (b) you wash with Ivory soap and swab with alcohol.


wacko.gif The record shows it was a) no washing & b) washing!
The prosecution with respect to the charges of illogicality and ignorance rest's it's case!

#25 LabGirl81

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Posted 24 January 2006 - 11:09 AM

The company I worked at about five years ago did a similar experiment to test out different cleanser formulations, and their effect on sebum production and moisturization (since it is still believed, even by research scientists at large well-known cosmetics companies that washing the skin can actually trigger an increase in sebum production). I did not conduct the test, but I was a very interested study participant (and the oiliest one of the bunch). I think they were actually testing the effectivness of some extract at different levels in the formula, versus a gentle clenser (pretty sure it was Cetaphil) and a harsh cleanser (which was supposed to cause the pores to secrete more sebum)

The first day we washed once wiped our faces with alcohol, our sebum production and water content were measured at baseline, and every 30 minutes for two hours, using a sebumeter, and they also used sebutape. The first week we didn't wash at all, and surface lipid content and water content was measured once every day. The we'd get a cleanser to use every morning for the week (in the lab of course). The rate of sebum production was measured with both sebutabe and some fancy expensive sebumeter, before washing, after washing, then every 15 minutes for an 90 minutes, then every two hours throughout the day (well until 5:00pm). The skin's moisturization was also measured, before washing, 15 minutes after and every two hours for the rest of the day. Each cleanser was used for a week this way for a week (a 5 day workweek). We weren't allowed to use any acne medications, use moisturizer, or wear makeup. It was a pain running down to the clinical lab all day, butI did have an excuse to get out of work. And I got a bunch of free makeup and 75$ for compensation.

I was curious about the results so when they were out I requested a copy of the study. It turned out that while there were signifigant differences in the skin moisture content between the diffwerent cleansers, there was no influence on actual sebum porduction for any of the cleansers. Surface lipid content was lowest right after washing, moisture content was lowest 30 minutes after cleansing, but the production rate of sebum didn't change at all, for anyone using any of the cleansers (there were slight variations, but nothing signifigant). Whatever extract that was in two of the cleansers wasn't as effective as they though it would be, so the study was actually not sucessful. When they wrote up their offical study they noted that sebum production is not influenced by cleansing (dispite using a mild surfactant, a harsh surfactant, and two different cleansers with different levels of some useless extract in it)......what was even more stange that in 5 day period where we didn't wash, the sebum production remained constant, and total surface lipid content was constantly incresaing, even though my own perception of oiliness seemed to diminish after a few days.

The original Kligman and Shelly study and another Kligman study were heavily referenced in the official write up........that's the first time I came across that study....

Every time I see in a magazine how washing the skin excessively or using harsh cleansers causes the pores to actually produce more oil I just laugh.....even some dermatologists still believe this (the people who devloped Proactiv even mention it in their little booklet)

Bryan does not have a sebumeter, so it's hard for him to get an actual quantitative number for the sebum production (this can be calculated by testing surface lipid content over a period of time and extrapolating the data). But he can get a good idea of a qualitative "rate" of sebum production using sebutabe, just by viewing the appearance of the strips over a period of time (the strips do not remove many surface lipids so it's not like all of the oil is removed)....

It's not like pores have little sensors that detect how dry the skin is and in turn churn out more oil. It's not even sebum that moisturizes the skin, it's the skin's lipid barrier and other natural moisturizing factors that prevent water loss.....there is even some evidance that sebum (actually the by products of sebum's bacterial degradation, namely unsaturated fatty acids) may actually damage the skin's water barrier, by causing abnormal keritinization and desquamation of cells of the stratum corenum....

#26 bryan

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Posted 24 January 2006 - 11:40 AM

QUOTE(L8302 @ Jan 24 2006, 12:30 AM) View Post

You have NOT proven, as you claim, that there is no significant difference between sebum production DURING periods of intense washing and periods of no washing. All you have proven is that the skin bounces back from being stripped/de-fatted/cleaned at the same rate whenever you use the same product/method (Ivory soap and alcohol).

For comparison, imagine you want to test soil water evaporation rates in cloudy v. sunny weather conditions. After a week of cloudy weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. After a week of sunny weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. SURPRISE, it's the same! In this circumstance you have failed to measure the rate of evaporation DURING the respective weather conditions by levelling the playing field during actual analysis. That the soil is dryer or wetter at the time of analysis doesn't affect the rate of evaporation given the exact same testing conditions.

Do you see what I'm saying?


Yes, I do understand what you're saying, although I think it's only a rather trivial point. However, it is indeed a limitation of the experiment I did (probably the ONLY limitation), and I congratulate you for noticing it. It's something that I've recognized myself in the past, and I've often wondered if anyone else would ever bring it up in these discussions.

Making a direct measurement of sebum production in the sebaceous glands would be extraordinarily difficult, of course, because those glands are deep within the skin; therefore, we have to use an indirect method, like measuring the rate at which sebum appears on the SURFACE of the skin. But there are even problems with that method, too, although they are not insurmountable. The most reliable way is to completely de-fat the skin first, then measure the amount of oil on the surface an hour or so later (or some other fixed time-interval that's relatively short). But that obviously leaves such a measurement open to an objection again based on the "feedback theory": what if even washing the oil from the surface of the skin (just as part of the test) immediately influences the production of sebum within the sebaceous glands, and queers the results of the test?

I suggest to you that although that IS a vague theoretical possibility, it's still not a very reasonable one. How plausible do you think it is that the mitosis of sebocytes within the sebaceous glands could be stimulated OVER THE COURSE OF A FEW MINUTES by something that occurs on the surface of the skin?? I think that's extraordinarily unlikely. The sebaceous response even to drugs like isotretinoin and powerful antiandrogens is a LOT slower than that, even taking into consideration the time it takes to achieve a local concentration of those drugs in the glands.

There's a tacit, unstated implication that always accompanies the feedback theory, which is that there's a relatively CONTINUOUS effect on the sebaceous glands that's caused by frequent washing; the hint is always that it's no use to wash the skin, because the glands will go into an oil-produceing mode, presumably around-the-clock. At the very least, my experiment dispenses with THAT idea! wink.gif

Bryan

#27 bryan

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Posted 24 January 2006 - 12:04 PM

QUOTE(gloriousbach @ Jan 24 2006, 03:57 AM) View Post

My own view is that the experiment is interesting, but doesn't properly answer the question that I and some others were interested in, which was does the type of cleanser used (or none at all) affect the rate of sebum excretion over the subsequent day or days.


Damn, you're a hard person to convince, GB! smile.gif

Even though I used Ivory soap and not Cetaphil Normal/Oily, you STILL don't think it's relevant to the Cetaphil?? Do you think that using Cetaphil Normal/Oily once or twice a day is an even MORE effective (and harsh) cleansing regimen than washing with Ivory soap 5-6 times a day?? Does that really seem reasonable to you?

Bryan

#28 LabGirl81

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Posted 24 January 2006 - 12:29 PM

QUOTE
[Ingredients in Ivory Soap:
Sodium tallowate (cleansing agent derived from beef tallow), Sodium cocoate or sodium palm kernelate (cleansing agents derived from coconut or palm oil), Water, Sodium chloride (salt), Sodium silicate (soluble glass), Magnesium sulfate (epsom salts), Fragrance


I had a lot of trouble finding that. It seemes like a typical ingredient label for a soap. The first two ingredients are traditional soaps (metal salts of fatty acids).

QUOTE
Ivory pH = 9.5 (water pH = 7)
True, Ivory has an alkaline pH and would thus seem like it would be harsh on the skin. However, the pH of something doesn't neccessarily speak to its total or net alkalinity. In fact, there is apparently little actual "free or available alkalinity" in Ivory soap.
"Available or free alkalinity is simply the concentration of alkalinity that is not tied up in formulation and is free and available to do work. Available alkalinity concentrations are measured by percentage. Common household detergent systems have no available alkalinity compared to instrument detergents. For example: Ivory Soap has a pH of 10 which is high on the alkaline scale but has no free or available alkalinity and, therefore, is safe enough to wash your face."

https://www.steris.com/documents/121611541392-6295_1.pdf


Theoretically Ivory soap should have a relatively low free alkalinity. But what happens when the soap dissolves in water??

The free alkalinity is usually determined using the ethanol method or the barium chloride method. In ethanol method soap is dissolved in neutralized ethanol, and the free alkali is titrated with an ethanol solution of HCL. The barium chloride method includes forming a precipitate of soap/carbonate by using barium chloride and determining resulting the alkalinity of the solution, which represents the alkalinity of the redsidual free metal hydroxide.

However, while it is true that many soaps have a low level of free alkalinity (compared to something like dishwashing detergant that utalizes a high level of free alkalinity), the pH (amount of free hydrogen ions in solution) is an indicator of how basic or acidic something is. Remember soap is water soluble to a certain degree. Alkaline water soluble substances cause the concentration of hydroxyl ions (OH-) in water solutions to be higher than the concentration of hydrogen ions (H+). Soap has a pH of say 10. So when soap dissolves in water there are more (OH-) ions in the medium than (H+) ions.....so it doesn't matter if the total free alkalinity in the soap is low, the pH is still high, and can cause fatty acids in the skin to loose (H+) ions.....

QUOTE
Ivory soap wouldn't have been my product of choice in order to conclusively demonstrate your point that 'excessive washing' or cleansing of the skin doesn't make a difference in sebum production levels. In any case, I think the test would have been more convincing if you had used something a little more harsh...


Maybe he should have used some dishwasher detergant...or maybe straight sodium lauryl sulfate...that's strong stuff.....

QUOTE
And then there's also the larger more significant issue (that possibly you weren't concerned with during this experiment) of the interplay of sebum production and acne. I'm playing devil's advocate here, but maybe the skin's regular sebum barrier is more effective at staving off acne when it is undisturbed rather than having it constantly replenished after cleansing/stripping (because of increased chance for bacteria to penetrate surface without the barrier.)


Sorry my friend, there is no such thing as skin's sebum barrier. Little kids hardly have any sebum. Oh and the palms of your hands and the soles of your feet have no sebceous glands either. Sebum does not form a protective barrier on the skin. The skin's barrier is actually maintained by layers of overlapping corneocytes, with alternating lipid bilayers and water layers in between. The barrier is reinforced by other epidermal lipids, like ceramides, and humectants that draw water into the skin. Epidermal lipids are not sebum. They are something entirely different.....however washing the skin removes both types of lipids, which can damage the skin's barrier function.....

#29 cjb

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Posted 24 January 2006 - 12:30 PM

QUOTE(bryan @ Jan 24 2006, 09:40 AM) View Post


Yes, I do understand what you're saying, although I think it's only a rather trivial point. However, it is indeed a limitation of the experiment I did (probably the ONLY limitation),




hmmm...not that I give a shit about the "feedback theory," but I do have to note one GLARING methodological shortcoming.... BIASED subject and experimenter.

#30 Daz!

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Posted 24 January 2006 - 12:30 PM

Has anyone done sebutape studies on the affects of ingested substances like caffeine, alcohol, sugar etc on sebum?



#31 bryan

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Posted 24 January 2006 - 12:37 PM

QUOTE(ballaballa @ Jan 24 2006, 08:22 AM) View Post

You cant do all the vigorous washing or non washing for a week, then next day wash your face, and then test. lol.gif Thats not what the feedback theory is. It's the theory that the washing itself will cause the skin to produce more oil. So you have to test same day.


HUH?? That doesn't even make sense. You seem confused.

You wash vigorously for a week, and measure sebum production. Then you stop washing for a week, and measure sebum production again. Then you compare the two rates (washing and non-washing). Which is exactly what I did. I can't figure out what the hell YOU were trying to say.

QUOTE
Also the use of alcohol really should not have been used because of its refining of pores. It DOES slow down the process in which oil comes out.


I'm not sure what you mean by "refining of pores". And even if it DID "slow down the process in which oil comes out" (I'd like to see some evidence for that), so what?? The point here is that I used the alcohol washing for BOTH phases of the test (Grunge mode and Washing mode), so they would be affected THE SAME. The only variable is the amount of washing during the previous week. That's how Science works, kiddo: you eliminate all the variables in a test, except for the specific one you're testing.

QUOTE
Also the fact that you tested only your forehead. Oil glands will not only produce in the area you washed, it will produce wherever an oil gland is. So when you were in your "grunge" period, oil glands were still working on your forehead.


What does THAT have to do with anything?? You're making less and less sense as time goes by.

QUOTE
Also the fact that you tested the same spot only. Testing it will remove the oil that was there and start again. So you didn't see an increase in sebum. It would have been smarter to test one spot at 2 1/2 hours and a different spot at 4 1/2.


I'll explain it to you again, Junior: I tested that one spot EXACTLY THE SAME WAY in both phases of the test (Grunge mode and Washing mode). If there was some small removal of sebum by the application of the Sebutape test-strip itself to that one spot on my forehead, then BOTH phases of the test were equally affected by it, eliminating that as a variable. You really don't understand the logic of a test like this, do you?

Bryan

#32 Daz!

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Posted 24 January 2006 - 12:40 PM

QUOTE(bryan @ Jan 24 2006, 10:40 AM) View Post

QUOTE(L8302 @ Jan 24 2006, 12:30 AM) View Post

You have NOT proven, as you claim, that there is no significant difference between sebum production DURING periods of intense washing and periods of no washing. All you have proven is that the skin bounces back from being stripped/de-fatted/cleaned at the same rate whenever you use the same product/method (Ivory soap and alcohol).

For comparison, imagine you want to test soil water evaporation rates in cloudy v. sunny weather conditions. After a week of cloudy weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. After a week of sunny weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. SURPRISE, it's the same! In this circumstance you have failed to measure the rate of evaporation DURING the respective weather conditions by levelling the playing field during actual analysis. That the soil is dryer or wetter at the time of analysis doesn't affect the rate of evaporation given the exact same testing conditions.

Do you see what I'm saying?


Yes, I do understand what you're saying, although I think it's only a rather trivial point. However, it is indeed a limitation of the experiment I did (probably the ONLY limitation), and I congratulate you for noticing it. It's something that I've recognized myself in the past, and I've often wondered if anyone else would ever bring it up in these discussions.

Making a direct measurement of sebum production in the sebaceous glands would be extraordinarily difficult, of course, because those glands are deep within the skin; therefore, we have to use an indirect method, like measuring the rate at which sebum appears on the SURFACE of the skin. But there are even problems with that method, too, although they are not insurmountable. The most reliable way is to completely de-fat the skin first, then measure the amount of oil on the surface an hour or so later (or some other fixed time-interval that's relatively short). But that obviously leaves such a measurement open to an objection again based on the "feedback theory": what if even washing the oil from the surface of the skin (just as part of the test) immediately influences the production of sebum within the sebaceous glands, and queers the results of the test?

I suggest to you that although that IS a vague theoretical possibility, it's still not a very reasonable one. How plausible do you think it is that the mitosis of sebocytes within the sebaceous glands could be stimulated OVER THE COURSE OF A FEW MINUTES by something that occurs on the surface of the skin?? I think that's extraordinarily unlikely. The sebaceous response even to drugs like isotretinoin and powerful antiandrogens is a LOT slower than that, even taking into consideration the time it takes to achieve a local concentration of those drugs in the glands.

There's a tacit, unstated implication that always accompanies the feedback theory, which is that there's a relatively CONTINUOUS effect on the sebaceous glands that's caused by frequent washing; the hint is always that it's no use to wash the skin, because the glands will go into an oil-produceing mode, presumably around-the-clock. At the very least, my experiment dispenses with THAT idea! wink.gif

Bryan


The feedback theory is based on analysis at what you call the level playing field, to me it isnt even trivial its irrelevant as people think they have observed the feedback theory at said level playing field.
'My skin gets oilier AFTER I wash it!' is what's being touted NOT 'DURING and bouncing back immediately after'. Try an move the goal posts all u want L8302!

#33 L8302

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Posted 24 January 2006 - 12:55 PM

Stellar reply. I am highly impressed that you granted me an inkling of credit for that observation. wink.gif

While I think you raise some important points about the inherent limitations of the experiment that you conducted, and while you seem to think that the test is the best that can be accomplished, I think a better or improved test can be devised. I think the real crux of the issue in the "feedback theory" is that your skin will be less oily (after a few days... it needs time to adjust) if you forego washing it (maybe to the exception of splashes of cold water/shower rinsing) rather than cleaning it all the time. I think the rate of sebum production isn't really the issue, although it could be a possible explanation relating to the hypothesis. So in order to takle the query of whether your skin is in fact less oily during periods of no washing versus periods of excessive washing, one could easily sample the sebum after 7 (or however many) days as is--no tampering or last minute cleaning. It seems to me that the next best measure to the rate of sebum production (which you so rightly pointed out would be very difficult--if not impossible--to measure during the phases) is to measure the total oil on the face.

Also, it would be better to allow the skin more "cooking time" before taking the samples-- even for the excessive-washing phase. If the feedback theory is correct, then your frequency of washing might be curtailing the excessive oil production at sample time. (Hmm was that clear?) So I would suggest taking the samples (from both the clean and grunge phases) in the morning when you first wake up (before any cleaning) after giving your skin plenty of time to produce that sebum overnight. Then one could clearly see if more net oil is produced... which is ultimately what I think is the concern.

Are you willing to try another experiment? Do you think these suggestions address what you were after or have I missed the target again...




QUOTE(bryan @ Jan 24 2006, 12:40 PM) View Post

QUOTE(L8302 @ Jan 24 2006, 12:30 AM) View Post

You have NOT proven, as you claim, that there is no significant difference between sebum production DURING periods of intense washing and periods of no washing. All you have proven is that the skin bounces back from being stripped/de-fatted/cleaned at the same rate whenever you use the same product/method (Ivory soap and alcohol).

For comparison, imagine you want to test soil water evaporation rates in cloudy v. sunny weather conditions. After a week of cloudy weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. After a week of sunny weather you bring the soil inside and test how fast it evaporates under a 60watt lightbulb. SURPRISE, it's the same! In this circumstance you have failed to measure the rate of evaporation DURING the respective weather conditions by levelling the playing field during actual analysis. That the soil is dryer or wetter at the time of analysis doesn't affect the rate of evaporation given the exact same testing conditions.

Do you see what I'm saying?


Yes, I do understand what you're saying, although I think it's only a rather trivial point. However, it is indeed a limitation of the experiment I did (probably the ONLY limitation), and I congratulate you for noticing it. It's something that I've recognized myself in the past, and I've often wondered if anyone else would ever bring it up in these discussions.

Making a direct measurement of sebum production in the sebaceous glands would be extraordinarily difficult, of course, because those glands are deep within the skin; therefore, we have to use an indirect method, like measuring the rate at which sebum appears on the SURFACE of the skin. But there are even problems with that method, too, although they are not insurmountable. The most reliable way is to completely de-fat the skin first, then measure the amount of oil on the surface an hour or so later (or some other fixed time-interval that's relatively short). But that obviously leaves such a measurement open to an objection again based on the "feedback theory": what if even washing the oil from the surface of the skin (just as part of the test) immediately influences the production of sebum within the sebaceous glands, and queers the results of the test?

I suggest to you that although that IS a vague theoretical possibility, it's still not a very reasonable one. How plausible do you think it is that the mitosis of sebocytes within the sebaceous glands could be stimulated OVER THE COURSE OF A FEW MINUTES by something that occurs on the surface of the skin?? I think that's extraordinarily unlikely. The sebaceous response even to drugs like isotretinoin and powerful antiandrogens is a LOT slower than that, even taking into consideration the time it takes to achieve a local concentration of those drugs in the glands.

There's a tacit, unstated implication that always accompanies the feedback theory, which is that there's a relatively CONTINUOUS effect on the sebaceous glands that's caused by frequent washing; the hint is always that it's no use to wash the skin, because the glands will go into an oil-produceing mode, presumably around-the-clock. At the very least, my experiment dispenses with THAT idea! wink.gif

Bryan



#34 bryan

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Posted 24 January 2006 - 01:14 PM

QUOTE(cjb @ Jan 24 2006, 12:30 PM) View Post

QUOTE(bryan @ Jan 24 2006, 09:40 AM) View Post

Yes, I do understand what you're saying, although I think it's only a rather trivial point. However, it is indeed a limitation of the experiment I did (probably the ONLY limitation),


hmmm...not that I give a shit about the "feedback theory," but I do have to note one GLARING methodological shortcoming.... BIASED subject and experimenter.


Hey, I've got a terrific idea: why don't YOU do the same test, CJB, and report your results here? The best part of it is that you don't give a shit about the results, so maybe the skeptics will believe you! wink.gif

Bryan

#35 bryan

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Posted 24 January 2006 - 01:26 PM

QUOTE(LabGirl81 @ Jan 24 2006, 11:09 AM) View Post

I was curious about the results so when they were out I requested a copy of the study. It turned out that while there were signifigant differences in the skin moisture content between the diffwerent cleansers, there was no influence on actual sebum porduction for any of the cleansers.


Hey, do you still have that copy?? smile.gif Is it considered, like, highly proprietary, or anything? I assume that this was an "in-house" document, right? It wasn't actually published outside of your company?

QUOTE
...what was even more stange that in 5 day period where we didn't wash, the sebum production remained constant, and total surface lipid content was constantly incresaing, even though my own perception of oiliness seemed to diminish after a few days.


This is SUCH an important statement, I'm quoting it here just for my pal ballaballa to see again. It supports my earlier testing, in which the sebum casual level on my forehead slowly increased over a period of 9 days (well, it was a total period of at least 12 days, actually, including the first 3 days when I didn't even bother to do any testing). People simply _must_ understand that casual, everyday observations of sebum on their skin aren't necessarily reliable. You _must_ test these theories and assumptions in a scientific manner.

QUOTE
The original Kligman and Shelly study and another Kligman study were heavily referenced in the official write up........that's the first time I came across that study....


I'm sure the first one was the original Kligman/Shelley paper, but what was the OTHER one?

QUOTE
Every time I see in a magazine how washing the skin excessively or using harsh cleansers causes the pores to actually produce more oil I just laugh.....


Me too. And then I do this----> eusa_wall.gif

Bryan

#36 bryan

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Posted 24 January 2006 - 01:42 PM

QUOTE(Daz! @ Jan 24 2006, 12:30 PM) View Post

Has anyone done sebutape studies on the affects of ingested substances like caffeine, alcohol, sugar etc on sebum?


Not to my knowledge. That would be a damned interesting avenue to explore.

Bryan

#37 bryan

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Posted 24 January 2006 - 01:56 PM

QUOTE(Daz! @ Jan 24 2006, 12:40 PM) View Post

The feedback theory is based on analysis at what you call the level playing field, to me it isnt even trivial its irrelevant as people think they have observed the feedback theory at said level playing field.
'My skin gets oilier AFTER I wash it!' is what's being touted NOT 'DURING and bouncing back immediately after'. Try an move the goal posts all u want L8302!


Yeah, you hit the nail on the head with that, Daz.

Everybody's skin gets oilier after they wash it (compared to how clean it is right AFTER they wash it), but anybody who is crazy enough to believe that it gets even oilier than it WOULD HAVE BEEN had they not washed at all, seriously needs to do some simple testing with a few Sebutape test-strips. They'll be quite surprised by the results! wink.gif

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#38 bryan

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Posted 24 January 2006 - 02:26 PM

QUOTE(L8302 @ Jan 24 2006, 12:55 PM) View Post

While I think you raise some important points about the inherent limitations of the experiment that you conducted, and while you seem to think that the test is the best that can be accomplished, I think a better or improved test can be devised. I think the real crux of the issue in the "feedback theory" is that your skin will be less oily (after a few days... it needs time to adjust) if you forego washing it (maybe to the exception of splashes of cold water/shower rinsing) rather than cleaning it all the time. I think the rate of sebum production isn't really the issue, although it could be a possible explanation relating to the hypothesis. So in order to takle the query of whether your skin is in fact less oily during periods of no washing versus periods of excessive washing, one could easily sample the sebum after 7 (or however many) days as is--no tampering or last minute cleaning. It seems to me that the next best measure to the rate of sebum production (which you so rightly pointed out would be very difficult--if not impossible--to measure during the phases) is to measure the total oil on the face.


L, you'll probably be surprised to hear that I've already conducted that experiment! smile.gif See my older thread entitled "If you stop washing, do you get MORE oily, or do you get LESS oily??" At this moment, it's down on the third page of this forum.

I completely stopped ALL washing for a period of at least 12 days, and began making Sebutape impressions on my forehead every day for 9 consecutive days, starting on the third day. They showed a gradually INCREASING level of oil and sebum over those 9 days. You can see the scan I made of them...I posted the link in that thread. Are you more satisfied now with my testing?

Bryan

#39 LabGirl81

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Posted 24 January 2006 - 03:24 PM

QUOTE
Hey, do you still have that copy?? smile.gif Is it considered, like, highly proprietary, or anything? I assume that this was an "in-house" document, right? It wasn't actually published outside of your company?


Nope. It was on my work email. I don't work for that company anymore. And yes, considering the size and power of that particular company it was considered highly proprietary (I think they have more patent attorneys than researchers over there). At the time it was only something that I was a little bit interested in, since everybody (even the researchers at the company I worked for) believed that if you wash the skin excessivly or use harsh surfactants it will produce more oil.....

QUOTE
I'm sure the first one was the original Kligman/Shelley paper, but what was the OTHER one?


I don't remember because I didn't actually look for that one (plus it was over five years ago)....they only sited it once or twice....it wasn't as interesting at the time I guess......



#40 L8302

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Posted 24 January 2006 - 03:30 PM

More satisfied... hesitant to say I've arrived at satisfaction island though.

Given that you seem to have investigated skin so thoroughly... might I ask what you would recommend to remedy or alleviate acne--by way of external regimen or otherwise? Are you listening LabGirl? Any ideas?

I'm sure you've graced other forums with this knowledge before, but I know not where to look...

Thanks O Wise One(s)

~L


QUOTE(bryan @ Jan 24 2006, 03:26 PM) View Post

L, you'll probably be surprised to hear that I've already conducted that experiment! smile.gif See my older thread entitled "If you stop washing, do you get MORE oily, or do you get LESS oily??" At this moment, it's down on the third page of this forum.

I completely stopped ALL washing for a period of at least 12 days, and began making Sebutape impressions on my forehead every day for 9 consecutive days, starting on the third day. They showed a gradually INCREASING level of oil and sebum over those 9 days. You can see the scan I made of them...I posted the link in that thread. Are you more satisfied now with my testing?