Measuring Climate Protection in Bags

[PrinceYonex]

I recently posted a thread asking whether climate protection in bags works, and the responses were useful but mostly anecdotal. Searching the boards, I couldn't find any threads where someone tried to measure the impact of these thermal insulation compartments. So, I decided to do a few very rudimentary experiments. I purchased a few bags and a couple of inexpensive thermometers. I placed the bags out in the sun for a 40 minute duration and measured what what was happening in the different parts of the bags. I kept the compartments fully zipped. I did this in northern California, where the outdoor temperatures were around 75-85 F. The thermometers measured temperature and humidity. They have a bluetooth function that allows me to monitor their measurements from my phone in realtime. I'm going to share some of the results. First, a quick proviso: I'm not making any strong claims about the relative merits of different bags. There are too many variables that I couldn't control for -- the various times of day when I conducted the temperature checks, the different materials used in each bag, even the different colors of the bags. I'll have some thoughts on these, but my main aim was just to see whether a compartment covered in reflective foil made any difference compared to a compartment that lacked it.

Experiment 1: The Yonex 75th Anniversary Elite 9-pack.
It's almost completely white and is 100% polyurethane. I put one thermometer in the foil compartment and one in a compartment without it. The bag was left in the sun, around noon on a fairly hot day. The outside temperature was around 80 F. When I placed the bag outside the temperature inside both compartments was 75, the humidity reading was around 55% in both. After 40 minutes, the temperature in both compartments had increased to 93 F. No difference. The reflective foil definitely did not keep the temperature down, it didn't even perform better than the non-foil compartment, with respect to temperature. One interesting note: in the non-foil compartment, the humidity spiked immediately, within the first five minutes, jumping to 80%, whereas in the foil, the humidity level showed only a slight increase in that initial period, up to 62%. Subsequently, the humidity levels dropped in both compartments down to the high 40s.

Experiment 2: Head 6 pack Tour Team Combi
It's mostly black. I'm not sure about the material composition. Same experiment -- thermometers in a foil covered compartment and in a non-foil compartment. Almost the same result: the temperature increased by the exact same amount in both compartments. The outside temperature was about 84 F, the starting temperature in both compartments was 75, the humidity level in both compartments was 55%. After 40 minutes in the sun, the temperature in both compartments was 100 F. No difference whatsoever, in terms of temperature. The difference, again, was seen in the humidity levels. In the compartment without foil, the humidity jumped in the first 5 minutes to 70%, whereas in the foil compartment, the humidity only went up slightly to 60%. In both compartments, the humidity went down to 34% by the end of the 40 minutes.

A few very brief conclusions: in both bags, the foil was utterly useless in keeping temperatures down or even in slowing down the rate of increase in temperature. In neither bag did the foil keep the temperature even with the outdoor temperature, much less "insulate" the compartment from the heat. The foil did seem to make a difference in preventing an initial humidity spike, which may or may not be relevant to people playing with natural gut strings, which are somewhat more vulnerable to moisture (honestly, I don't know if these kinds of brief humidity spikes impact the strings).

 

[PrinceYonex]

I conducted an additional set of experiments, trying to compare head to head.

Experiment 1: Yonex 75th Elite (white) vs. Head Combi 6 pack (black)
I placed the thermometers only in the foil compartments of each bag. Both bags performed virtually identically with respect to humidity, but the Yonex outperformed the Head with respect to temperature. The outside temperature was 72, and the temperature in both bags to begin was 71. After 40 minutes, the temperature in the Yonex had risen to 83, whereas the temperature in the Head rose to 94. This difference seemed fairly significant.

Experiment 2: Same bags but I placed a white towel over the Head Combi. No towel on the Yonex.
This experiment was inspired by a comment on these boards from maybe ten years ago, that placing a white towel over a bag can have a greater impact than thermo-guards in insulating a racquet compartment. Here's where things got interesting. The two bags now performed virtually identically. In both bags, the temperature only rose from 74 to 85.

So, does the towel work? I tried one more experiment:

 

[PrinceYonex]

I pulled out my trusty old Babolat expandable bag, which has no foil in any of its compartments.

Experiment 1, no towels: Head combi (with foil and no towel) vs. Babolat expandable (with no foil and no towel)
Both bags are black. The materials feel different, but I don't know their exact composition. The outside temperature was 75 F, and the temperature in both bags was 75 at the start. The humidity in both bags was 50%. After 40 minutes, the temperature in the Head was 92, and the temperature in the Babolat was 94. I don't consider this difference to be sizable enough to be significant. The foil in the head did not substantially outperform the Babolat without any insulation. However, as with the earlier experiment, the Babolat without foil showed a brief humidity spike, rising from 51% to 66% after 7 minutes, whereas the foil compartment in Head only showed a very slight increase, from 50% to 54%. The humidity in both bags fell below 40% in both bags by the end.

Experiment 2: Head combi (with foil but no towel) vs. Babolat expandable, no foil but with a white towel on top of it
The outside temperature was 75, and at the start the temperature in each bag was around 75-76 F. The humidity in both bags was around 50%. After 40 minutes the temperature in the Head (foil) rose to 89 F, whereas the temperature in the Babolat (no foil but towel-covered) only rose to 83F. This difference may not be statistically significant. I'm not sure. The towel did, however, prevent a humidity spike in the Babolat, which only rose 52% after 10 minutes, before it came back down.

Does the white towel work? It's hard to tell from these numbers alone. It did seem to keep both the temperature and the humidity from spiking up.

 

[PrinceYonex]

Preliminary conclusions: I obviously didn't test every big brand. And I didn't control for important variables regarding material composition, a constant outdoor temperature, etc. So I don't think any of these numbers can really be used to assess whether the insulating technology in one brand is better than another. But the initial conclusion here seems to be that the reflective foil really doesn't do anything to keep the temperature in the compartment down or even to slow its rate of increase. This is most evident when comparing, simultaneously, the performance of two compartments in one bag, one with foil and the other without. The foil insulation does seem to have an impact on humidity fluctuations. But, a white towel on top of the bag seems to be just as effective with humidity and, in some cases, more effective at keeping temperatures down, as compared to reflective foil.

 

[jeep2008]

Good job.Thanks for your time.

 

[socallefty]

With high temperature in the summer, I don’t feel like it has any impact on the string playability whether the temperature inside my bag where my racquets are stored are at 70 degrees or 90 degrees. On the other hand when it is cold in the winter, it would be nice if the bag has any insulating effect and prevents the strings from getting too cold quickly. Strings at 40 degrees feel stiffer than strings at 50 or 55 degrees for sure.

Humidity used to be a factor in gut string lifetimes a couple of decades ago before the top brands like Babolat developed good protective coatings. Now, I can play with gut/poly hybrids on very humid days or in light drizzle and it doesn’t seem to affect my string’s lifetime.

So, I primarily buy bags based on the design of their storage compartments, zipper quality and looks.

 

[puppybutts]

I conducted an additional set of experiments, trying to compare head to head.

Experiment 1: Yonex 75th Elite (white) vs. Head Combi 6 pack (black)
I placed the thermometers only in the foil compartments of each bag. Both bags performed virtually identically with respect to humidity, but the Yonex outperformed the Head with respect to temperature. The outside temperature was 72, and the temperature in both bags to begin was 71. After 40 minutes, the temperature in the Yonex had risen to 83, whereas the temperature in the Head rose to 94. This difference seemed fairly significant.

Experiment 2: Same bags but I placed a white towel over the Head Combi. No towel on the Yonex.
This experiment was inspired by a comment on these boards from maybe ten years ago, that placing a white towel over a bag can have a greater impact than thermo-guards in insulating a racquet compartment. Here's where things got interesting. The two bags now performed virtually identically. In both bags, the temperature only rose from 74 to 85.

So, does the towel work? I tried one more experiment:

you mentioned briefly not controlling for different factors, including the color of the bag. i will just reiterate, yes since the yonex bag is white and the head bag is black, i would expect the yonex to outperform in terms of temperature - this was backed up by your towel experiment. i never really trusted climate protection material to do much, since it's not like the zippers are appropriately sealed anyway. but i am surprised that according to your experiment, it didn't even delay how long it took to get hot.

thanks for doing this. i always meant to do a less exact experiment by just leaving a frozen water bottle in the bag and seeing how long it took to melt in various pockets lol.

i am curious now though...are lunch boxes just a big scam? because climate protected tennis bags and lunch boxes seem to use the same technology....i never understood why so many lunch boxes only come in black colors.

 

[PrinceYonex]

you mentioned briefly not controlling for different factors, including the color of the bag. i will just reiterate, yes since the yonex bag is white and the head bag is black, i would expect the yonex to outperform in terms of temperature - this was backed up by your towel experiment. i never really trusted climate protection material to do much, since it's not like the zippers are appropriately sealed anyway. but i am surprised that according to your experiment, it didn't even delay how long it took to get hot.

thanks for doing this. i always meant to do a less exact experiment by just leaving a frozen water bottle in the bag and seeing how long it took to melt in various pockets lol.

i am curious now though...are lunch boxes just a big scam? because climate protected tennis bags and lunch boxes seem to use the same technology....i never understood why so many lunch boxes only come in black colors.

Yes, I agree about the impact of color. I can’t make this claim directly from my testing because other factors, like the materials used to make the bag, might also contribute to the differences in performance.
With regard to color, it’s not only lunch boxes that seem so often to be black but tennis bags too! It’s actually really odd but so many bags that TW sells are very dark in color, if not simply black. It’s actually a challenge to find lighter colors, or bags that are mostly white.
Fortunately it’s easy to obtain a white towel!

 

[ollinger]

Nothing surprising about these results particularly given that the bags have full length zippers that easily facilitate the conduction of heat. That your findings took place in a 40 minute span should give pause to those who've posted here in the past wondering if their racquets are protected when they're at work all day, using the racquets either on the way to or on the way home from the job

 

[PrinceYonex]

Nothing surprising about these results particularly given that the bags have full length zippers that easily facilitate the conduction of heat. That your findings took place in a 40 minute span should give pause to those who've posted here in the past wondering if their racquets are protected when they're at work all day, using the racquets either on the way to or on the way home from the job

I definitely would not count on the reflective foil to somehow insulate the racquets, or really to do anything protective in regards to temperature, if the bag itself is sitting in a car that’s baking in the heat.

 

[temnik]

.

 

[PrinceYonex]

I recall watching some documentary about an endurance hike through a desert. Those hikers used light reflective foil blankets to shield themselves from sun and to create shade. They were saying that the relief only lasts for 5-10min, and then it's like sitting in an oven.

So, save your money: buy a cheap light colored bag and a white towel.

OTOH maybe we are supposed to stick a few freezer packs into a bag.

Yes, I think this is exactly right. And for what it’s worth, in my limited testing the reflective foil inside the tennis bags didn’t even moderate temperatures for that first 5-10 minutes, as compared with non-foil compartments in the same bag. It made no difference at all, with respect to temperature.

 

[socallefty]

What exactly is bad for a racquet or strings if the temperature is 90-110 degrees vs 60-70 degrees? I thought graphite racquets, poly/nylon/gut strings should all be unaffected at these temperatures. For me, temperature insulation is more important in cold weather as I don’t want my strings to get stiff and unresponsive like they do below 40 degrees.

 

[PrinceYonex]

What exactly is bad for a racquet or strings if the temperature is 90-110 degrees vs 60-70 degrees? I thought graphite racquets, poly/nylon/gut strings should all be unaffected at these temperatures. For me, temperature insulation is more important in cold weather as I don’t want my strings to get stiff and unresponsive like they do below 40 degrees.

Does the foil keep the temperature up, compared with non-foil, in cold weather? I’m never playing below 40 F, so I haven’t checked this with thermometers. My testing has made me skeptical that the foil has much value at all.

 

[Rosstour]

When discussing care/feeding of my 'new' PS85 to be strung with full bed of natural gut, my stringer said to use an insulated bag and do not keep it in the car. He's not a dummy. Even a little bit helps.

 

[PrinceYonex]

When discussing care/feeding of my 'new' PS85 to be strung with full bed of natural gut, my stringer said to use an insulated bag and do not keep it in the car. He's not a dummy. Even a little bit helps.

I started these tests because I often play with gut, and I was a bit concerned about big temperature swings.
For sure, don’t leave it baking in a car, especially on a day when it will heat up way above the outside temperature. But you should throw a couple temperature gauges in your bag, one in the foil, one not, leave it in your car for a half hour, and see if there’s any difference in temperature. My own experimenting with this leads me to guess that there wouldn’t be. Not even by a small amount.

 

[socallefty]

Does the foil keep the temperature up, compared with non-foil, in cold weather? I’m never playing below 40 F, so I haven’t checked this with thermometers. My testing has made me skeptical that the foil has much value at all.

I don‘t know, but anything that is supposed to keep temperature stable should work when the temperature goes down outdoors from room temperature just like it is supposed to work when the temperature goes up. If your testing is right, maybe it is not very effective at colder temperatures either.

 

[PrinceYonex]

I don‘t know, but anything that is supposed to keep temperature stable should work when the temperature goes down outdoors from room temperature just like it is supposed to work when the temperature goes up. If your testing is right, maybe it is not very effective at colder temperatures either.

Yeah, exactly. I don’t know if the foil reacts differently under the pressure of cold temperatures. But I no longer accept the idea that these “insulated compartments” actually keep temperature stable, certainly in relation to hot temperatures.

 

[socallefty]

I found a good article about the effect of temperature on strings. Hopefully these damn bags work.

http://twu.tennis-warehouse.com/learning_center/temperature.php

 

[eah123]

If the intent of the foil compartment is to keep the temperature down and reduce the humidity, since the latter is being achieved but not the former, should players with NG strings put an ice pack in the compartment?

 

[PrinceYonex]

If the intent of the foil compartment is to keep the temperature down and reduce the humidity, since the latter is being achieved but not the former, should players with NG strings put an ice pack in the compartment?

I thought about this, but one problem is that ice packs themselves produce moisture. So you might keep the temperature down, or possibly even lower the temperature, but you might end up raising the humidity in the compartment. Now, if a bag company made this like my children's lunch packs, where there is a separate attached compartment for the ice pack, allowing for the cold to be transferred without the moisture, then you'd be on to something!

 

[Addxyz]

What exactly is bad for a racquet or strings if the temperature is 90-110 degrees vs 60-70 degrees? I thought graphite racquets, poly/nylon/gut strings should all be unaffected at these temperatures. For me, temperature insulation is more important in cold weather as I don’t want my strings to get stiff and unresponsive like they do below 40 degrees.

We're told to store all of our unused strings out of the sun and in a somewhat cool place. Wouldn't string that is in heat expand and lose its elasticity (themal expansion)? I guess the next experiment might be to string up a racquet, measure tension after 24 hours after it has settled, then try measuring tension at different temperatures and durations. 110F is probably not hot enough to melt the glue and resins in the racquet, but car temperatures are much higher than 110F and consistent high temperature might weaken the glue, maybe even deform and weaken grommets?

 

[eah123]

I thought about this, but one problem is that ice packs themselves produce moisture. So you might keep the temperature down, or possibly even lower the temperature, but you might end up raising the humidity in the compartment. Now, if a bag company made this like my children's lunch packs, where there is a separate attached compartment for the ice pack, allowing for the cold to be transferred without the moisture, then you'd be on to something!

Ice packs don't actually produce moisture. They dehumidify the air by making the water vapor condense. If you were concerned that condensation from the ice pack would get on the racquet, you could just wrap the ice pack in a microfiber towel. I doubt an ice pack would be effective enough to lower the racquet frame's temperature enough to produce condensation.

 

[esgee48]

We're told to store all of our unused strings out of the sun and in a somewhat cool place. Wouldn't string that is in heat expand and lose its elasticity (thermal expansion)? I guess the next experiment might be to string up a racquet, measure tension after 24 hours after it has settled, then try measuring tension at different temperatures and durations. 110F is probably not hot enough to melt the glue and resins in the racquet, but car temperatures are much higher than 110F and consistent high temperature might weaken the glue, maybe even deform and weaken grommets?

At any temperature, the string will stretch until the remaining tension is equal to the force required to stretch the string. With synthetics like Nylon, a 20 F° increase will let the string stretch more and probably result in a drop in tension of ~3-4# since the string is not fully elastic. Hitting a ball at those higher temperatures results in a higher tension loss rate, e.g. you will lose control sooner. Polyester, whether alone or with other co-polymers, will act exactly the same way, though they do not recover any tension when temperatures cool. So here, you will have a material with no recovery combined with materials that may recover tension back. The net effect is a higher proportionate loss than just straight Nylon based.

If you store strings in sunlight, the UV will destroy chemical bonds. The string will become brittle and less able to hold tension. Heat will also do this, but a lot slower than direct sunlight.

Racquets are not affected by temperatures that human beings consider hot.

 

[jeep2008]

Does the foil keep the temperature up, compared with non-foil, in cold weather? I’m never playing below 40 F, so I haven’t checked this with thermometers. My testing has made me skeptical that the foil has much value at all.

We need to find someone at the southern hemisphere now ,to make this experiment for us

 

[ollinger]

Of course the elephant in the room is whether foil lined racquet compartments make matters WORSE by trapping heat inside the bag when your racquets are in the car or by the court on a hot sunny day.

 

[esgee48]

The foil would work if it were outside the bag to reflect radiant energy AWAY from the interior. That is what a white towel on top of the bag does. It would slow the transfer of heat into the bag. Problem is conduction would not stop and the temperature in the bag will still rise, tho much more slowly.

Heat transfer rate is dependent on the difference in temperature (ΔT) can be treated as "constant" over narrow temperature ranges. This implies that going from a heated environment to a much colder one would result in the same/near same temperature change rates. So going from 70 F° to 40 F° vs going from 40 F° to 70 F° should be approximately the same elapsed time.

 

[str33tspirit]

What the foil does is keeping my cold drinks cold.

 

[golden chicken]

Thanks for doing this experiment!

 

[golden chicken]

Seems to support my hypothesis that it's only good for temperature shock protection.

i.e. walking out to your car with your bag when its much hotter or colder outside than it is inside.

Interesting to see that the uninsulated part of a bag is just as good at that as the insulated part is.

 

[PrinceYonex]

Seems to support my hypothesis that it's only good for temperature shock protection.

i.e. walking out to your car with your bag when its much hotter or colder outside than it is inside.

The foil might help with minimizing a jump in humidity in the bag, but I'm not sure that it is doing anything to minimize temperature shock. My own testing didn't actually involve going from indoors straight to a car that had been left in the sun for an hour, where it might be over 100 degrees. That kind of extreme temperature difference is probably where the most shock would take place. Unfortunately, I don't have data on that. But in moving from indoors to outdoors on a hot day, the insulation in the bag didn't slow the rate of increase in temperature, as compared to a non-insulated compartment in the very same bag.

 

[PrinceYonex]

Interesting to see that the uninsulated part of a bag is just as good at that as the insulated part is.

Or, just as bad!

 

[struggle]

NASA type studies say "it can't hurt".

Anyone who thought these would actually do much good might want to think harder.

I just wish they put the suff in ALL compartments so i could see things better.

 

[puppybutts]

NASA type studies say "it can't hurt".

Anyone who thought these would actually do much good might want to think harder.

I just wish they put the suff in ALL compartments so i could see things better.

that'd be unnecessarily expensive lol, they could just make the interior a different color. a lot of camera or hunting bags have a high visibility interior, light gray or bright orange, could be a good idea....unless you are a head radical owner

 

[CosmosMpower]

I'm not surprised, unless the foil is on the outside I doubt it would do anything. Mostly marketing gimmicks.

 

[PrinceYonex]

I'm not surprised, unless the foil is on the outside I doubt it would do anything. Mostly marketing gimmicks.

@esgee48 mentioned this above also. It helps make sense of the fact that a simple white towel on top of a bag -- even a bag with no special insulation -- is at least as effective, if not more so, than a foil compartment in black bag.

 

[Strawbewwy]

I'm curious if towel is acting as an insulation layer (think double walled jugs) or rather just light color deflecting the heat away.

some suggestion if you have the time

what about using a black towel? black towel vs white towel

how about double towel? 1 towel vs 2 towel

Thanks for the fun experiment!

 

[jeep2008]

This is Wilson's Thermoguard 2.0 ad

Perhaps the Silica Gel Desiccant Bag does something about humidity at least.They do claim though that they offer protection against humidity AND heat.

 

[PrinceYonex]

This is Wilson's Thermoguard 2.0 ad

Perhaps the Silica Gel Desiccant Bag does something about humidity at least.They do claim though that they offer protection against humidity AND heat.

Is the thermoguard 2.0 in all their current bags that have insulation? I didn’t test any Wilson bags. In terms of that dessicant bag: the thing is that regular foil compartments already do a good job of mitigating a humidity spike— as does the white towel. So I’m not sure what extra effect this gel would offer.

 

[jeep2008]

Is the thermoguard 2.0 in all their current bags that have insulation? I didn’t test any Wilson bags. In terms of that dessicant bag: the thing is that regular foil compartments already do a good job of mitigating a humidity spike— as does the white towel. So I’m not sure what extra effect this gel would offer.

Yeap,we should keep on testing

 

[celito]

I would think this reflective foil material is most effective when its surface is actually exposed to sunlight as in when you use it in a car windshield so that it can reflect the light. Seems kind of useless if it's used in this manner. Unless I am missing something.

 

[celito]

I recently posted a thread asking whether climate protection in bags works, and the responses were useful but mostly anecdotal. Searching the boards, I couldn't find any threads where someone tried to measure the impact of these thermal insulation compartments. So, I decided to do a few very rudimentary experiments. I purchased a few bags and a couple of inexpensive thermometers. I placed the bags out in the sun for a 40 minute duration and measured what what was happening in the different parts of the bags. I kept the compartments fully zipped. I did this in northern California, where the outdoor temperatures were around 75-85 F. The thermometers measured temperature and humidity. They have a bluetooth function that allows me to monitor their measurements from my phone in realtime. I'm going to share some of the results. First, a quick proviso: I'm not making any strong claims about the relative merits of different bags. There are too many variables that I couldn't control for -- the various times of day when I conducted the temperature checks, the different materials used in each bag, even the different colors of the bags. I'll have some thoughts on these, but my main aim was just to see whether a compartment covered in reflective foil made any difference compared to a compartment that lacked it.

Experiment 1: The Yonex 75th Anniversary Elite 9-pack.
It's almost completely white and is 100% polyurethane. I put one thermometer in the foil compartment and one in a compartment without it. The bag was left in the sun, around noon on a fairly hot day. The outside temperature was around 80 F. When I placed the bag outside the temperature inside both compartments was 75, the humidity reading was around 55% in both. After 40 minutes, the temperature in both compartments had increased to 93 F. No difference. The reflective foil definitely did not keep the temperature down, it didn't even perform better than the non-foil compartment, with respect to temperature. One interesting note: in the non-foil compartment, the humidity spiked immediately, within the first five minutes, jumping to 80%, whereas in the foil, the humidity level showed only a slight increase in that initial period, up to 62%. Subsequently, the humidity levels dropped in both compartments down to the high 40s.

Experiment 2: Head 6 pack Tour Team Combi
It's mostly black. I'm not sure about the material composition. Same experiment -- thermometers in a foil covered compartment and in a non-foil compartment. Almost the same result: the temperature increased by the exact same amount in both compartments. The outside temperature was about 84 F, the starting temperature in both compartments was 75, the humidity level in both compartments was 55%. After 40 minutes in the sun, the temperature in both compartments was 100 F. No difference whatsoever, in terms of temperature. The difference, again, was seen in the humidity levels. In the compartment without foil, the humidity jumped in the first 5 minutes to 70%, whereas in the foil compartment, the humidity only went up slightly to 60%. In both compartments, the humidity went down to 34% by the end of the 40 minutes.

A few very brief conclusions: in both bags, the foil was utterly useless in keeping temperatures down or even in slowing down the rate of increase in temperature. In neither bag did the foil keep the temperature even with the outdoor temperature, much less "insulate" the compartment from the heat. The foil did seem to make a difference in preventing an initial humidity spike, which may or may not be relevant to people playing with natural gut strings, which are somewhat more vulnerable to moisture (honestly, I don't know if these kinds of brief humidity spikes impact the strings).

You could probably bring a lawsuit against these manufacturers if you can undoubtedly prove that this **** doesn't work at all. I think Babolat had to refund money for their racquets not having tungsten in them a while back as adverstised.

 

[PrinceYonex]

I would think this reflective foil material is most effective when its surface is actually exposed to sunlight as in when you use it in a car windshield so that it can reflect the light. Seems kind of useless if it's used in this manner. Unless I am missing something.

Yes, a few others in this thread suggested this as well— that the foil would need to be outside to be effective. That maybe starts to help explain some of what I discovered by putting an ordinary towel on top. And yes, I think the foil is essentially useless for regulating temperatures. The materials of the bag and it’s color seem to matter much more.

 

[PrinceYonex]

You could probably bring a lawsuit against these manufacturers if you can undoubtedly prove that this **** doesn't work at all. I think Babolat had to refund money for their racquets not having tungsten in them a while back as adverstised.

What an idea! A more litigious and proactive person could and perhaps should do this. I really just wanted a bag that would help insulate my strings.

 

[PrinceYonex]

These guys also ran a test on climate control compartments in bags:

Does Climate Protection in a Tennis Bag Actually Work?

One of the most debated questions among tennis players when it comes to tennis bags is whether a bag’s advertised climate protection feature actually works or not. Depending on the bag brand, this may also be called Climate Control, Thermoguard, or Isothermal Protection.

geausport.com

They tended to match my overall conclusions (although they don't mention humidity, where possibly these foil compartments might make a short-term difference).

 

[Rabbit]

All that foil stuff ever did was tear after a use due to the over grips on my frames. My Yonex bag which stands up doesn't have it on either side. I prefer not to have it at all.

 

[Hagberg]

As many already have said in this thread, for foil to be useful, the reflective surface must be directed towards the incoming radiation. The reflected (heat) rays must also have somewhere to go so even if the foil material is reflective on both sides, it won't do much if there is an outer layer absorbing the reflected heat. To use physics to maximum advantage, a bag should be totally reflective on one side and totally black on the other. The reflective surface should be turned towards the sun and the black surface away from it so the bag can radiate away the most internal heat. This will only work for radiative heating.

In a situation where the bag is just sitting in a generally warm (or cold) environment without a direct radiation source (like in a car), the only way is to have very good isolation or active cooling (or heating).
Isolation will delay heating but eventually, just like a thermos, temperatures will even out and equal the outside of the bag.
Active cooling or heating can easily be implemented DIY by using common cooling blocks that we use for portable cooling boxes. Two or three blocks will probably be enough to delay extreme temperatures over a typical tennis session.

For a high end bag, I'm waiting for someone who will implement active cooling and heating powered by solar power cells integrated on the outer surfaces of the bag or perhaps in a foldable format reminiscent of the towel used to cover the bags in the tests above. It should be possible to extract 60 - 120W out of a typical bag surface area depending on bag size and panel efficiency. Unfortunately, a cheap thermoelectric cooler will not keep up with that little power available so something better is needed.
Besides temperature regulation, some portable solar power could always be used for other stuff so it wouldn't be a total gimmick.

 

[golden chicken]

As many already have said in this thread, for foil to be useful, the reflective surface must be directed towards the incoming radiation. The reflected (heat) rays must also have somewhere to go so even if the foil material is reflective on both sides, it won't do much if there is an outer layer absorbing the reflected heat. To use physics to maximum advantage, a bag should be totally reflective on one side and totally black on the other. The reflective surface should be turned towards the sun and the black surface away from it so the bag can radiate away the most internal heat. This will only work for radiative heating.

In a situation where the bag is just sitting in a generally warm (or cold) environment without a direct radiation source (like in a car), the only way is to have very good isolation or active cooling (or heating).
Isolation will delay heating but eventually, just like a thermos, temperatures will even out and equal the outside of the bag.
Active cooling or heating can easily be implemented DIY by using common cooling blocks that we use for portable cooling boxes. Two or three blocks will probably be enough to delay extreme temperatures over a typical tennis session.

For a high end bag, I'm waiting for someone who will implement active cooling and heating powered by solar power cells integrated on the outer surfaces of the bag or perhaps in a foldable format reminiscent of the towel used to cover the bags in the tests above. It should be possible to extract 60 - 120W out of a typical bag surface area depending on bag size and panel efficiency. Unfortunately, a cheap thermoelectric cooler will not keep up with that little power available so something better is needed.
Besides temperature regulation, some portable solar power could always be used for other stuff so it wouldn't be a total gimmick.

Ok, so forget the physics required to make a temperature regulating bag a reality, just assume as a thought experiment that it's possible to make a bag that maintains a set temperature and humidity level. What temp/humidity would you select? Say, 70F, 50%? What happens when you take the raxket out of the bag to use it on a sunny, 90F day in Florida with the humidity around 70%?

So, really the next experiment should be, do the rackets/strings experience more stress when allowed to change temp inside a bag over 5-10 minutes, or when taken out of a climate controlled environment and directly into a much different environment.

 

[PrinceYonex]

Ok, so forget the physics required to make a temperature regulating bag a reality, just assume as a thought experiment that it's possible to make a bag that maintains a set temperature and humidity level. What temp/humidity would you select? Say, 70F, 50%? What happens when you take the raxket out of the bag to use it on a sunny, 90F day in Florida with the humidity around 70%?

So, really the next experiment should be, do the rackets/strings experience more stress when allowed to change temp inside a bag over 5-10 minutes, or when taken out of a climate controlled environment and directly into a much different environment.

Dropping a thermometer in a bag is one thing. Not sure how you would measure the “stress” on racquets or strings due to temp changes.

 

[golden chicken]

Dropping a thermometer in a bag is one thing. Not sure how you would measure the “stress” on racquets or strings due to temp changes.

Oh, I'm not asking you to do the experiment, I'm just trying to reiterate my "temperature shock" hypothesis from earlier.

We can all agree that high temps inside a car are no good for a racket or strings. But we also agree that we play in a variety of conditions between cool and hot, while we store our rackets generally some temperature in the middle. So, is it better to let the racket slowly acclimate between conditions, or just take it outside and play? Does it even matter?