EG advise against Topy rubber soles

[DWFII]

Originally Posted by apropos

Solution? Turn your shoes upside down.

If only! Moist air is lighter than dry air, not the other way around. Simple physics. H2O weighs less than O2 or N2.
Is that right? That's why fog hugs the ground, why it rains... H2O is three molecules two of which are in semi-solid state. O2 is two molecules. I'm not a physicist I could be wrong but would you care to reconsider?

 

[apropos]

Oh dear.

 

[fritzl]

Originally Posted by flanker2000fr

...

no offense, this is a discussion around the emperors beard. i hear you walking, though.

 

[Claus]

Originally Posted by DWFII

Fact: For centuries all scientists were "armchair scientists" who obtained their knowledge and credentials through direct, hands-on experience and observations...

This used to be correct, until scientists figured out that observations alone cannot confirm or reject a theory. Only scientific experimentation is able to do that. This means to reduce all possible outside influences except one which is thought to be the cause of the studied effect.

Additionally, by the same means scientists figured out that people have biases concerning observations and experience. Recollections are not that precise, and are often "recreated" according to the theories one holds. Careful and complete documentation is key to scientific knowledge.

Consenquently, a proposition like "Leather insoles on shoes with rubber soles turn black and crack sooner than if the outsoles are also leather" is not scientific unless you have complete notations about the age of the shoes, its usage, other behaviour of its wearer, the objective quality of the insole, etc. and a proper statistic evaluation what most likely caused the effect you noted.

Just saying.

 

[bloke11]

Originally Posted by DWFII

Is that right? That's why fog hugs the ground, why it rains... H2O is three molecules two of which are in semi-solid state. O2 is two molecules. I'm not a physicist I could be wrong but would you care to reconsider?
Don't forget that dry air is a composition of oxygen and nitrogen. If humid air is denser then there would be zero chance of cloud formation or rain as it wouldn't rise in the first place.

 

[Journeyman]

Originally Posted by apropos

Moist air is lighter than dry air, not the other way around. Simple physics. H2O weighs less than O2 or N2, and for a given pressure there is an equal number of molecules per unit volume.

Originally Posted by DWFII

Is that right? That's why fog hugs the ground, why it rains...

H2O is three molecules two of which are in semi-solid state. O2 is two molecules.

I'm not a physicist I could be wrong but would you care to reconsider?


This discussion risks getting off topic!

Whilst it seems counter-intuitive, it is correct that moist air is lighter than dry air.

This is because the water vapour in moist air displaces other gases that normally comprise air. For example, if you have a litre of moist air, and a litre of dry air, the moist air will contain fewer 02 and N2 molecules as they will have been displaced by water vapour.

Whilst H2O would, at first thought, be a larger molecule, it is not as heavy as O2 or N2. This is because Hydrogen is extremely light - it has an atomic weight of 1, whilst oxygen has an atomic weight of 16 and nitrogen has an atomic weight of 28. So, one molecule of water vapour will have an atomic weight of 18 (16 +1+1), whilst a molecule of oxygen will have an atomic weight of 32 and a nitrogen molecule will have an atomic weight of 56.

Therefore, by reducing the density of O2 and N2, and replacing it with H2O, moist air is quite a bit lighter (relatively speaking, of course, as air is already very light!) than dry air.

 

[DWFII]

Originally Posted by Claus

This used to be correct, until scientists figured out that observations alone cannot confirm or reject a theory. Only scientific experimentation is able to do that. This means to reduce all possible outside influences except one which is thought to be the cause of the studied effect. Additionally, by the same means scientists figured out that people have biases concerning observations and experience. Recollections are not that precise, and are often "recreated" according to the theories one holds. Careful and complete documentation is key to scientific knowledge. Consenquently, a proposition like "Leather insoles on shoes with rubber soles turn black and crack sooner than if the outsoles are also leather" is not scientific unless you have complete notations about the age of the shoes, its usage, other behaviour of its wearer, the objective quality of the insole, etc. and a proper statistic evaluation what most likely caused the effect you noted. Just saying.
I agree with you...it begs the question, though, doesn't it?-- Compared to what?

 

[DWFII]

Originally Posted by Journeyman

This discussion risks getting off topic! Whilst it seems counter-intuitive, it is correct that moist air is lighter than dry air. This is because the water vapour in moist air displaces other gases that normally comprise air. For example, if you have a litre of moist air, and a litre of dry air, the moist air will contain fewer 02 and N2 molecules as they will have been displaced by water vapour. Whilst H2O would, at first thought, be a larger molecule, it is not as heavy as O2 or N2. This is because Hydrogen is extremely light - it has an atomic weight of 1, whilst oxygen has an atomic weight of 16 and nitrogen has an atomic weight of 28. So, one molecule of water vapour will have an atomic weight of 18 (16 +1+1), whilst a molecule of oxygen will have an atomic weight of 32 and a nitrogen molecule will have an atomic weight of 56. Therefore, by reducing the density of O2 and N2, and replacing it with H2O, moist air is quite a bit lighter (relatively speaking, of course, as air is already very light!) than dry air.
I have no credentials or expertise to question you but perhaps you could clarify by answering a few of my lingering doubts... Is oxygen heavier than water? If so, why does water pool and oxygen "float"? When we speak of "moist air" are we talking about a different and perhaps unknown third molecular compound with characteristics different from either oxygen or water? Or are we talking about a gas "transporting" a semi-solid? I see it as being similar to a dirigible...is the dirigible more buoyant with or without a payload? Speaking about "moist air" and water "vapour" is convenient but it disguises the fact that it is not really one thing, it is two--water and air. It is not, now that I think about it, three molecules (H2O) versus two molecules (O2 or N2). It is really five molecules--two hydrogen and three oxygen. From a layman's point of view, water is heavier than air, ipso facto any combination of water and air must be heavier than air alone. As in the dirigible analogy. Or is that wrong and if it is, how so? And to bring it all back around to the topic at hand, how is my relatively uninformed speculation about the physics of moist air any different from the patently ignorant speculation about leather insoles and outsoles and whether Topy prevents beneficial wicking?

 

[DWFII]

Originally Posted by bloke11

Don't forget that dry air is a composition of oxygen and nitrogen. If humid air is denser then there would be zero chance of cloud formation or rain as it wouldn't rise in the first place.
I'm not sure I understand this...both oxygen and nitrogen are heavier than hydrogen and yet they seem to rise in the atmosphere just fine. Here's my thoughts/speculation... Because one element is denser/heavier than another doesn't mean that it cannot rise in the atmosphere nor that a compound ...as opposed to the element itself...can't exhibit different characteristics. And when it comes to moist air we are not even talking about a compound are we? The compound is water. Moist air is just a suspension of water in air. Air transports water. It is not a molecular compound. Does that make any sense?

 

[apropos]

...and this kids is why being an armchair scientist is not a good thing.

 

[DWFII]

Originally Posted by apropos

...and this kids is why being an armchair scientist is not a good thing.

Are you a scientist? A physicist? I am asking...I am open-minded enough to not only admit my lack of expertise but to ask for instruction. How about you? About any subject? I suspect that in the long run, if only for personal growth, it is far better to be an armchair scientist and employ reason and experience and knowledge than to be an internet dilettante and employ Google and Wikipedia. At least I'm not pretending.

 

[saint]

This thread has really gone off the rails. FWIW, I've used Topy's on good (EG, CJ for RL, Grenson, Alden etc) shoes for years. After a couple of years I'll stop replacing the Topy and let it and then the sole wear down, and then have the shoes resoled. I have never had a problem with any of my shoes, but I do use shoe trees and give shoes a minimum of a day's rest in between wearings. I can't imagine that moisture stays in the sole significantly longer under these circumstances.

As far as the opinion that Topys on the bottom of shoes look "inelegant", if someone's weird enough to care what the soles of my shoes look like, I really don't care what they think.

 

[Claus]

Originally Posted by DWFII

I agree with you...it begs the question, though, doesn't it?-- Compared to what?
The topic is whether leather soles with Tobys causes a faster destruction of the insole compared to pure leather soles, isn't it? Quick research reveals that one's feet are among the most perspiring parts of the body, with more than 250,000 sweat glands each. In one day, each foot can produce more than a pint of sweat, about half a liter for us Europeans. Given usual usage, a fraction thereof remains in your socks, in the shoe, and also in the air that may be pumped in and out of the shoes while you walk. So, we can probably agree that the amount of sweat in your shoes is affected at least by

• the sort of socks one wears,
• how often one changes socks during a day,
• how much one walks,
• the type of shoes, and
• its fit.

For instance, "closed" shoes like boots are less likely to have air pumped in and out during walking, so their insoles have to deal with more moisture compared to 'common' shoe types. My guess would be that the socks absorb the larger amount of moisture. Expressed differently, a bad habit of wearing the same pair of socks for two days in a row is likely to have a worse effect on the insoles than Topys. We can probably also agree that the rest of the sweat is absorbed by the upper and the insole alike. Without further information, absorption is a matter of the available surface. Consequently, the upper absorbs a larger fraction of the sweat compared to the insole. It's hard to say -- given all the variables -- how much moisture remains in the insole after a day of wear. For the sake of the discussion, however, let's assume it's a teaspoon full of water, basically. Now, let's consider evaporation... We can probably also agree that evaporation is also a matter of available surface. The upper has larger surface, so it should dry faster than the insole. Your analogy to a teaspoon, however, fails here since is has a smaller surface compared to the insole. For a fairer test, you should put a teaspoon of water on a small plate and have it rest for 24 hours. We can probably also agree that the layer of cork, tarboard or tar paper is a barrier to evaporation, so only another fraction of the moisture in the insole will ever reach the outsole. In other words, some amount of moisture will probably remain in a Goodyear-welted shoe forever unless it's used seldom. Now, how much moisture could ever reach the outsole? A millimeter or two, maybe? Let's say five. So, this is what a Toby would do: Prevent five millimeter of sweat to evaporate from the inside. At the same time, though, it prevents outside water to be absorbed by the outsole. It's really hard to tell what the net effect would be. Even if the net effect is negative, there's also the question if the cumulative effect matters. Consider for example the different prices of shoes. A rather cheap 400 dollar shoe is unlikely to be affected by the cumulative effect, because it's probably broken due to other causes before moisture will matter. 1000 dollar shoes are more likely to live long enough for Topys to have a negative effect; even more so for 2000 dollar shoes. In other words: Just the average price of shoes may explain the difference between your and NickV's observations, provided Nick repairs less expensive shoes on average. tl;dr Science is complicated.

 

[Pendulum]

Originally Posted by DWFII

I have no credentials or expertise to question you but perhaps you could clarify by answering a few of my lingering doubts... Is oxygen heavier than water? If so, why does water pool and oxygen "float"?
Oxygen, by its molecular weight is heavier than water, but that's neither here nor there. Water is liquid at room temperature, whereas pure oxygen is gas which means that water is far more dense than oxygen at RT. The reason behind this is water forms hydrogen bonds between each molecule which has a great effect on the boiling points of the liquid, due to the molecules being highly attracted to each other and energy being required to overcome this barrier.

Speaking about "moist air" and water "vapour" is convenient but it disguises the fact that it is not really one thing, it is two--water and air. It is not, now that I think about it, three molecules (H2O) versus two molecules (O2 or N2). It is really five molecules--two hydrogen and three oxygen. From a layman's point of view, water is heavier than air, ipso facto any combination of water and air must be heavier than air alone. As in the dirigible analogy. Or is that wrong and if it is, how so?

You're thinking too much into this. Water is not heavier than air, it is denser than air when comparing liquid water and gaseous air. However by being vaporised (in a gaseous state) Dalton's law states that the total pressure is the sum of the partial pressures of each individual component of the constituent gas. That is to say that dry air for example may have a pressure of 1, with components 70% N, 20% O, 10% other gases. So you can write this as 1=0.7P(N2)+0.2P(O2)+0.1P(others) If you then have moist air you are increasing the relative level of H2O, whilst decreasing the level of N2, O2 etc. which are heavier per molecule than H2O. This means that assuming the pressure does not increase, the partial pressures of N2, O2 and other gases would decrease to accommodate for the additional H2O in the air. Say there was 5% water in the air by composition then: 1=0.67P(N2)+0.19P(O2)+0.09P(others)+0.05P(H2O) If we then assign molecular weights to each (N2 = 28, O2 = 32, others = 15, H2O = 18) then the two are. Dry = 27.5g per pressure unit Moist = 26.95g per pressure unit Massively geeky first post here.

 

[Nicola]

Originally Posted by DWFII

I'm not sure I understand this...both oxygen and nitrogen are heavier than hydrogen and yet they seem to rise in the atmosphere just fine.

Here's my thoughts/speculation...

Because one element is denser/heavier than another doesn't mean that it cannot rise in the atmosphere nor that a compound ...as opposed to the element itself...can't exhibit different characteristics.

And when it comes to moist air we are not even talking about a compound are we? The compound is water. Moist air is just a suspension of water in air. Air transports water. It is not a molecular compound.

Does that make any sense?


Think of compressed gas. In it's heavily compressed form you have lots of gas in a small space. Now release the pressure and it goes flying around.

If it gets cold enough oxygen does become a liquid. If water gets hot enough it turns to a gas (aka steam). In it's gas form you'll notice it rises.