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Does soap get less soapy near the center?


jsharr

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I think that a bar of soap has less soapy sudsy goodness near it's center.  It seems to me that a new bar of soap leaves a nice thick lather on my wash cloth, but the sliver left as the bar fades off to eternity is much less sudsy and lathery.

Discuss.

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3 minutes ago, jsharr said:

I think that a bar of soap has less soapy sudsy goodness near it's center.  It seems to me that a new bar of soap leaves a nice thick lather on my wash cloth, but the sliver left as the bar fades off to eternity is much less sudsy and lathery.

Discuss.

Wouldn't it just be less surface area between the hands (with water) and the soap bar resulting in less potential (and therefor actual) lather?

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Just now, Razors Edge said:

Wouldn't it just be less surface area between the hands (with water) and the soap bar resulting in less potential (and therefor actual) lather?

How does the time component factor in?  I rub and rub and rub with the small bar and no lather.  A few rubs with the new bar, lots of lather?  

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2 minutes ago, jsharr said:

How does the time component factor in?  I rub and rub and rub with the small bar and no lather.  A few rubs with the new bar, lots of lather?  

A new bar vs an old bar is probably a 10x or 20x surface area differential, so rub for four or five minutes and let us know your results.

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1 hour ago, jsharr said:

I think that a bar of soap has less soapy sudsy goodness near it's center.  It seems to me that a new bar of soap leaves a nice thick lather on my wash cloth, but the sliver left as the bar fades off to eternity is much less sudsy and lathery.

Discuss.

Wrong.  It's the same carp all the way through.  It's the surface area that changes.  You cyclists are stupid.

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1 hour ago, jsharr said:

I think that a bar of soap has less soapy sudsy goodness near it's center.  It seems to me that a new bar of soap leaves a nice thick lather on my wash cloth, but the sliver left as the bar fades off to eternity is much less sudsy and lathery.

Discuss.

You spelled 'discus' wrong.

You are right, though, it is as if somebody (aliens?) is stealing the sudsyness right when we need it most!

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2 minutes ago, Randomguy said:

You spelled 'discus' wrong.

You are right, though, it is as if somebody (aliens?) is stealing the sudsyness right when we need it most!

James and the other buttholes are wrong with the science and logic.  I think it is drain aliens.

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1 hour ago, Razors Edge said:

Wouldn't it just be less surface area between the hands (with water) and the soap bar resulting in less potential (and therefor actual) lather?

 

1 hour ago, jsharr said:

How does the time component factor in?  I rub and rub and rub with the small bar and no lather.  A few rubs with the new bar, lots of lather?  

 

1 hour ago, Razors Edge said:

A new bar vs an old bar is probably a 10x or 20x surface area differential, so rub for four or five minutes and let us know your results.

 

1 hour ago, wilbur said:

So bigger requires less rubbing to achieve desired results than smaller.  Makes sense. 

 

1 hour ago, Square Wheels said:

That wasn't as exciting as I'd hoped.

...you were rubbing the wrong thing.

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25 minutes ago, James said:

Wrong.  It's the same carp all the way through.  It's the surface area that changes.  You cyclists are stupid.

I think you are right but WRONG! at the same time.  I think all the sudsy oils have left the inner bar during previous showers through a seeping or fracking kind of pathway, leaving the inert substrate behind to frustrate us all.  I must be right, based on my authoritative opining abilities I spoke about yesterday.

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1 minute ago, Randomguy said:

I think you are right but WRONG! at the same time.  I think all the sudsy oils have left the inner bar during previous showers in a fracking kind of pathway, leaving the inert substrate behind to frustrate us all.  I must be right, based on my authoritative opining abilities I spoke about yesterday.

...as the forum's expert on rubbing, I defer to your opinion in this.

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Just now, Randomguy said:

I think you are right but WRONG! at the same time.  I think all the sudsy oils have left the inner bar during previous showers in a fracking kind of pathway, leaving the inert substrate behind to frustrate us all.  I must be right, based on my authoritative opining abilities I spoke about yesterday.

This from a shoe-stealing, witch murderess.  :( 

Stuff doesn't migrate to the outside, it is a single bar of homogeneous nature originally poured into a mold.  The center is exactly the same as the outside.

You people need to opine on something you know about, like how to peep into your neighbor's windows and such.   

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9 minutes ago, Randomguy said:

I think you are right but WRONG! at the same time.  I think all the sudsy oils have left the inner bar during previous showers through a seeping or fracking kind of pathway, leaving the inert substrate behind to frustrate us all.  I must be right, based on my authoritative opining abilities I spoke about yesterday.

RG is right.  The essence of suds has been leached out.

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6 minutes ago, James said:

This from a shoe-stealing, witch murderess.  :( 

Stuff doesn't migrate to the outside, it is a single bar of homogeneous nature originally poured into a mold.  The center is exactly the same as the outside.

You people need to opine on something you know about, like how to peep into your neighbor's windows and such.   

WRONG! (maybe) .  The surface area theory is correct, though.

 It is only the same at the start of things, because soap is apparently like a snowcone, in that the sudsy flavor gets sucked out before the ice fully melts.  I only wish there was some sort of medical doctor here named Mickin that knew something about chemistry and could set us straight on the matter.

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Today, soaps are made from fats and oils that react with lye (sodium hydroxide). Solid fats like coconut oil, palm oil, tallow (rendered beef fat), or lard (rendered pork fat), are used to form bars of soap that stay hard and resist dissolving in the water left in the soap dish.

Soaps are often superfatted, so after all of the lye has reacted with the fats, there are still fats left over. This is important for two reasons. First, the resulting soap is easier to cut, and feels smoother on the skin. Second, the extra fats make sure that all of the lye reacts, so no lye is left to irritate the skin, and the resulting soap is not too alkaline.

 

Polyethylene glycols such as PEG-6 methyl ether may be added as either surfactants, detergents, emulsifiers (to make the dyes and perfumes blend evenly), or as thickeners.

Glycerine is added as an emollient and texture enhancer. Sorbitol is another emollient used along with glycerine. It is often added to help make glycerine soaps more transparent. Titanium dioxide is added to make the soap opaque.

Pentasodium pentetate, tetrasodium etidronate and tetrasodium EDTAare added as water softeners, and to protect the dyes and perfumes from the effects of metal ions in the mixtures. These compounds lock up calcium and magnesium in the water, preventing them from reacting with the soap to form insoluble soap scum.

https://sci-toys.com/ingredients/soap.html

Did you really want to know some of this about soap?

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4 minutes ago, maddmaxx said:

Today, soaps are made from fats and oils that react with lye (sodium hydroxide). Solid fats like coconut oil, palm oil, tallow (rendered beef fat), or lard (rendered pork fat), are used to form bars of soap that stay hard and resist dissolving in the water left in the soap dish.

Soaps are often superfatted, so after all of the lye has reacted with the fats, there are still fats left over. This is important for two reasons. First, the resulting soap is easier to cut, and feels smoother on the skin. Second, the extra fats make sure that all of the lye reacts, so no lye is left to irritate the skin, and the resulting soap is not too alkaline.

 

Polyethylene glycols such as PEG-6 methyl ether may be added as either surfactants, detergents, emulsifiers (to make the dyes and perfumes blend evenly), or as thickeners.

Glycerine is added as an emollient and texture enhancer. Sorbitol is another emollient used along with glycerine. It is often added to help make glycerine soaps more transparent. Titanium dioxide is added to make the soap opaque.

Pentasodium pentetate, tetrasodium etidronate and tetrasodium EDTAare added as water softeners, and to protect the dyes and perfumes from the effects of metal ions in the mixtures. These compounds lock up calcium and magnesium in the water, preventing them from reacting with the soap to form insoluble soap scum.

https://sci-toys.com/ingredients/soap.html

Did you really want to know some of this about soap?

yes.  tell me more please.

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19 minutes ago, James said:

This from a shoe-stealing, witch murderess.  :( 

Stuff doesn't migrate to the outside, it is a single bar of homogeneous nature originally poured into a mold.  The center is exactly the same as the outside.

You people need to opine on something you know about, like how to peep into your neighbor's windows and such.   

...I am impressed by your proper use and correct spelling here of "homogeneous."

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William asks,"when a bar of soap gets used a lot and gets smaller. It seems to struggle to form suds properly. Is it something other than just a smaller surface area going on?"

 

Answer

Eva has been scrubbing up to answer this question from William...

Eva - Alan Calverd from the forum said "my guess is that most soaps include volatile and easily soluble components that aid lathering, as the bar shrinks its surface to volume ratio increases. So these components are lost more rapidly". But what do the experts think. Phillip Broadwith, business editor at chemistry world for the Royal Society of Chemistry, gave us this answer.

Phillip - The reason a small soap bar doesn't make such a good lather is mostly down to surface area. To form bubbles you need to dissolve soap in water and then agitate it and with a small bar of soap you can only dissolve the soap molecules at the surface of the bar. With a large bar the water on your wet hands is in contact with quite a large area, so can dissolve quite a lot of soap quite quickly and make a generous lather. But with the smaller bar you surface area in contact with your hand is smaller. So even if you have the same amount of water on your hands the soap is released more slowly.

Eva- Paul Dauenhauer, associate professor of chemical engineering and material science at the University of Minnesota, and soap enthusiast, had this to add.

Paul - A three dimensional object like a bar of soap that shrinks half its original size actually only has one eighth of the original surface area. People are not scrubbing with the bar that much longer and the perception is that they are not getting as much soap transferred to their hands.

Eva - Right. So by that math to use a bar of soap that's gone down to half its original size you'd need to be scrubbing your hands for eight times longer. No wonder we get impatient.

Paul - A second impact is a perception of the bar by the hand washer with time, soap bars are made of heavy molecules such as soap molecules but they also contain light components that enhance the handwashing experience. A person washing their hands is aware of some of the compounds that add color and odor but other components are added to have additional benefits such as stabilizing a foam or eliminating the effects of hard water.

Eva - Hard water, like we suffer in Cambridge, contains metals which bind to the soap molecules and stop them from being able to clean properly. Soap manufacturers add special compounds called chelants which will bind to the metals and protect the soap molecules. But what does this have to do with getting a good lather from a small bar of soap.

Paul - Overtime these lighter compounds will evaporate into the air or preferentially leach into the water faster than the heavier soap compounds. The end result is that the smaller soap bar is less effective later in its life at forming stable lathery foams that are good for washing your hands.

 

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4 hours ago, jsharr said:

I think that a bar of soap has less soapy sudsy goodness near it's center.  It seems to me that a new bar of soap leaves a nice thick lather on my wash cloth, but the sliver left as the bar fades off to eternity is much less sudsy and lathery.

Discuss.

I think there's less surface area to produce the suds so it seems like the sliver isn't doing much.

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You see people, this is why we need a government grant!  It is snot trivial.

My theory is that both factors are in play. That is a good point aboot the soap also getting much thinner so the surface area goes down drastically, but I think it also gets denser and less active as it shrinks due to exposure to all that water.  After all, you only really use the one surface- the thickness doesn’t really matter.  Maybe this is why bath gel was invented, for a more uniform lathering experience. 

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7 minutes ago, RalphWaldoMooseworth said:

You see people, this is why we need a government grant!  It is snot trivial.

My theory is that both factors are in play. That is a good point aboot the soap also getting much thinner so the surface area goes down drastically, but I think it also gets denser and less active as it shrinks due to exposure to all that water.  After all, you only really use the one surface- the thickness doesn’t really matter.  Maybe this is why bath gel was invented, for a more uniform lathering experience. 

You see you are wrong here, as least as far as the one surface.  A bar of soap has 6 surfaces.   For gits and shiggles, lets say we had a square cube of soap 4" on a side.  Surface area of a cube is A=6a2 where a = lenght of one side.

So 6*4= 6*16=96

Lets say we use half the cube.  

Now we have 6*22 or 6*4=24

So using half the cube cuts the surface area by 3/4, so the argument is valid, but I still think some of the active ingredient leaches out through usage so you have greatly diminished surface area and a weaker soap.

I still like RG's alien theory.  I kind of get turned on thinking there are aliens in the drain stealing my soap and laughing at my junk.

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Quote

For a given volume, the object with the smallest surface area (and therefore with the smallest SA:V) is the sphere, a consequence of the isoperimetric inequality in 3 dimensions. By contrast, objects with tiny spikes will have very large surface area for a given volume.

https://en.wikipedia.org/wiki/Surface-area-to-volume_ratio

 

...thus, the ideal bar of soap would look like this:

_D.jpg

 

Quote

For a given shape, SA:V is inversely proportional to size. 

And it would weigh about six to ten pounds. :) 

 

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  • 2 years later...
13 minutes ago, Randomguy said:

So why, if we can design moon rockets, realistic sex robots with self-cleaning body parts, and sour cream in squeezey bottles, can we not design soap that is soapier in the middle?

I still blame the junk staring drain aliens.

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  • 2 years later...

I recently bought some Ivory soap.  I will not do that again.  It is very soapy, but it gets brittle when it gets thin and breaks apart and for some reason, bits of Ivory do not stick back together like other soaps do.   Not sure if I should post this here, or in the soap sorcery thread or start a new thread.

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On 5/7/2019 at 9:51 AM, jsharr said:

I think that a bar of soap has less soapy sudsy goodness near it's center.  It seems to me that a new bar of soap leaves a nice thick lather on my wash cloth, but the sliver left as the bar fades off to eternity is much less sudsy and lathery.

Discuss.

There is less surface area when the bar gets small so not as much suds is produced.

Back in the 50's, I can remember my father saving tiny bars of soap for his shaving mug where, with some added water, he'd stir a shaving brush in it and generate shaving suds.

Today, a user of Gillette Foamy Shaving Cream, I try to use my bars of soap to as small as I can comfortably hold them, then throw them away.

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