Neoprene characteristics

[trux]

Besides it, I believe that the images on Yamamoto's website are not only incorrectly used (demonstrating the opposite of their claim), but additionally they do not even show a person in any neoprene suit. I firmly believe that they are IR images of a person(s) in trousers but with naked torso. The person definitely does not have any standard neoprene suit with long waist or farmer john trousers - you could see the shape of the trousers pretty well. And strangely, below the waist, there is no IR emission at all. Looks like the bottom is made from at least 500mm platinum coated neoprene .

On my mind, it clearly shows that the images were just shamelessly stolen from somewhere else, but have absolutely no relation to Yamamoto's neoprene.

 

[wet]

Metallic coating should definitely improve the insulation properties, but unfortunately the photos show the exact opposite.

Metallic coatings improve reflection of radiation back to the source but allow faster conduction from the source.

Seems to me that any metallic coating would not be significantly better than not, largely due to the many seams which would leak heat laterally. But I dunno.

 

[trux]

Metallic coatings improve reflection of radiation back to the source but allow faster conduction from the source.

Seems to me that any metallic coating would not be significantly better than not, largely due to the many seams which would leak heat laterally. But I dunno.

The conduction would be negligible, especially because it is a thin coating used in sandwich. Such kind of metallic coating is often used in diverse extreme or emergency applications and works pretty well both for keeping the heat out (i.e. fire-fighting) or inside (i.e. emergency covers). However, I agree that the effect on the coated neoprene is questionable. Not so much due to the seams, but because of the coating itself. Metal, even in foils, does not really strech well, so it is certainly not a continuous foil, but rather just some kind of coated elastic textile with many holes. Still, its reflective property should be better than at plain neoprene, and I doubt the increased flat conductivity would eliminate the effect entirely. If there are any seriously and scientifically made measurements or comparisons, I'd love to see them, though. The pictures on their website are a joke.

An easy and relatively reliable way would be cutting a Ti and a normal wet-suits in length into two halves and gluing them together, making so a half Ti/half standard wetsuit. Thermographic imagery would then tell better about the real difference.

 

[Mr. X]

Found this interesting link on neoprene: [ame=http://en.wikipedia.org/wiki/Neoprene]Neoprene - Wikipedia, the free encyclopedia[/ame]

"For diving and exposure protection applications, the air spaces in the neoprene are filled with nitrogen for its insulation value...since neoprene contains many porous air-spaces, the material compresses the greater the depth it is exposed to."​

[Not sure I follow the logic there but make of it what you will].

Re. the picture - does it show the "Ti diver" is warmer or loosing more heat? I'm with Dave & Trux on this one -- looks to me like he has less thermal insulation (or he got hotter putting that jacket on). Afterall, this is the technique used by Universities to study heat loss from buildings. [Whenever I see see Titanium or Ti associated with a product I just think "marketing b*llocks". Even for ice screws & bike frames, there are better, cheaper alternatives, IMHO.] His trousers look like great insulators though -- maybe we should find out what material they are (jacket looks a little short for a wetsuit).

I suppose covering the inside of a wetsuit with a conductor might have some other interesting effects, like distributing body heat - which might be good (avoids localised over heating/chill) or bad (working against the body's mechanisms for maintaining core body temperature).

 

[John Askew]

Not sure if this picture will show but if it does then this should put an end to the argument.

John

P.S. If this image does not show, please would somebody tell me how to post images. In the URL address box I put the picture address. i.e. J:\My Pictures\IR Insulation.jpeg

 

[John Askew]

Not sure if this picture will show but if it does then this should put an end to the argument.

John

P.S. If this image does not show, please would somebody tell me how to post images. In the URL address box I put the picture address. i.e. J:\My Pictures\IR Insulation.jpeg

 

[John Askew]

Previous message was in response to the argument presented by ncunuclear718

 

[trux]

Previous message was in response to the argument presented by ncunuclear718

The image is not visible. Unless it is available online (then you only need to enter its URL), you have to upload the image - click the Go Advanced button, then the Attachment icon (paper clip), select the file on your disk with the help of the Browse button, and upload.

BTW, you do not need to add new redundant posts for every new attempt or modification - you can always edit (or delete) your previous posts by simply clicking the button Edit at the bottom of your original message.

 

[John Askew]

Hope it works this time.

Basically if the insulation is good then it blocks the IR rays passing through and the radiation that reaches the camera is low intensity. This results in a blue image.

If the insulation is poor then it lets more rays pass through and the radiation reaching the camera is of high intensity resulting in a red image.

So the more red in the picture the more radiation is passing through the insulation and therefore the insulation is poor.

But of course, as trux pointed out, you can only compare different insulants using this method if the IR source emits the same intensity of IR radiation.

Not a great picture

 

[Spaniard]

Wow another John Askew, same name as me but I go by first name Juan as I have Spanish roots. Pleased to meet you, first time I've met another John Askew

 

[Jon]

I understand what John is saying. It reminds me of that anti-perspirent commercial where the jewel thief covers himself in the product so as not to set off the heat sensors in the museum as he steals the gem.rofl

My concern with any of the Ti linings is that they are normally put on to make the suit slide on easier, and not to reflect heat. Since they make the suit slide on easier they don't trap water as well as a standard opencell. Opencell might be a pain to put on compared to a lined suit, but it does trap water better, and it doesn't matter how much heat your radiating back if you get a constant flow of water through your suit.

Back to the start of the thread, I would like to see a suit that Jim had mentioned- argon blown rubber instead of nitrogen blown. I know from my ice, and trimix, diving that I stay warmer when my dry suit is pumped full of argon compared to air. Argon is denser and I wonder if the cells would break down more slowly as a result- which is why a new looking suit, on the outside, can loose it's buoyancy and warmth after a few hundred dives.

Another option that might become more viable in the future is a hot water suit for freediving. I'm sure that Sven can tell us how great it is to dive in one while your sucking off the hose, and I had an early model that was battery powered in an old dry suit. Mine worked OK, but not nearly as well as better underwear and argon. I even tried the heating pad in my wet suit with some success. I know that they have come a long ways in the past 13 years since I bought mine, but I wasn't super impressed at the time. In the future, when heating and battery technologies advance a few steps, I could see being able to ice dive in a 3mm suit with heat wires running through the suit and attached to a small weight belt made out of batteries. Instead of just relying on the rubber itself to keep you warm it could be the hot water that gets flushed through the suit that does the job.

In the end, I feel, there is only so far the rubber can take you without adding something else into the mix.

Jon

 

[Seacidal]

Jon,

I was having virtually this exact discussion yesterday with a dive buddy. I agree completely that the Ti, metallic, ceramic, etc. coating/lining on open cell neoprene is a mixed blessing.

On the upside, it can make the suit easier to put on. I already lube up my suits, so this isn't a big plus for me.

But the downside is that is coats (and often occludes) the open cell pores. This reduces the ability of the open cells to cling to your skin and prevent water movement.

On your other comment about a hot water suit. I recently saw (online) a "hotpack" that a diver could warm in hot water or microwave, and then insert into an elastic band to be worn around the waist. It was reported to provide heat for an hour or so. Not quite the same as a hotwater suit, but a start.

For my diving on my boat, I've tapped into the engine's hot water system with a small marine heat exchanger, and am able to heat either fresh or raw water. A hose and nozzle on deck allow divers to warm up their suits both before putting them on, and in between dives. Not to mention a welcome hot water shower at the end of the day. It's worth its weight in gold!

Chip

 

[NiallFlinn]

Hi folks,

I just wanted to make a point about John's assertion that insulation blocks IR rays. That's not actually what insulation does.

Basically, there are a couple of different heat transfer processes involved here:

The first (and probably more important in diving) is conduction. One material (skin, for example) touches another material (say, water). If the first material is hotter than the second material, its fast-vibrating atoms pass some of their energy to the atoms in the second material. Conduction happens only by contact.

The second is radiation, the process by which hot materials lose energy by emitting photons (or EM waves if you're thinking about it that way).

Neoprene may well block IR radiation, but the main reason it keeps you warm (and will make the wearer appear cooler on an IR sensitive camera) is that it prevents conduction by keeping layers of fluid (water and bubbles of gas, which don't conduct well) between your skin and the suit's exterior. The cooler the exterior of the suit, the less IR it will emit and the cooler it will appear on and IR camera.

An example of a material that insulates well but probably doesn't block IR well is transparent plastic bubble wrap. It's a very good insulator, but also transparent to many frequencies of radiation.

Aluminium foil, on the other hand, is exactly the opposite: it blocks IR very effectively but is a terrible insulator.

The reason that things like loft insulation, pipe lagging, and firemen's suits are made from both foamy materials and shiny metallic materials is because you need the combination to block both conduction and radiation effectively. The use of metallic coatings in wetsuits makes conceptual sense in this context, but as conduction is the major form of heat loss in diving, the actual effect is probably marginal.

Cheers,

Niall

Hope it works this time.

Basically if the insulation is good then it blocks the IR rays passing through and the radiation that reaches the camera is low intensity. This results in a blue image.

If the insulation is poor then it lets more rays pass through and the radiation reaching the camera is of high intensity resulting in a red image.

So the more red in the picture the more radiation is passing through the insulation and therefore the insulation is poor.

But of course, as trux pointed out, you can only compare different insulants using this method if the IR source emits the same intensity of IR radiation.

Not a great picture

 

[trux]

I just wanted to make a point about John's assertion that insulation blocks IR rays. That's not actually what insulation does. ...

That's, of course partially right, but it does not change anything on the fact that the picture on Yamamoto's website are used in a wrong way. They wanted to demonstrate that the Titanium coated material insulates better because besides the conductivity insulation properties (common at other neoprenes), it also has improved radiation insulation properties. But they took just some pictures found on the web or elsewhere, and mixed them incorrectly (apparently knowing nothing about thermography).

On the other note, you are not quite right because IR thermography actually does not measure only the pure IR radiation of the source, but also of the IR emissions of the insulator being heated by the conduction (or of any other material between the sensor and the source - including the air, of course). So the worse conductive properties the material has, the warmer it appears on an IR image. You can only eliminate the conductive IR part by attaching it immediately before taking the image, not giving it chance to heat up through the conductivity too much. But that's appaarently not easily possible if measuring a real wetsuit on a human body, because putting it on already necessarily takes some time.

Also, as I already wrote multiple times, you really need to have identical starting conditions and times the insulator covers the source heat to be able comparing any such images.