Temperature under a hat

[ThomasK]

Yesterday it was a boring day - I had too much time. So I did a test which temperature is under two different hats when the sun is shining.

I just put a thermometer under a white cheap paper hat (they call it panama but it is not) and a black wool hat.

Temperature in shadow was just 17 centigrade (63F) but full sun.

The temp. under the white was 34 centigrade(93F), under the felt 38 centigrade (100F)

I really was surprised how warm it is even when the ait temp. in shadow is quite low.

I am wondering which temp. would be when the hat is on my head – because my head is also producing heat. This would be interesting because black is absorbing infrared radiation and white reflects it. That means white reflects the IR from the sun and black absorbs it – what is one of the reasons it is warmer with the black one. BUT the heat of the head is also IR radiation and will be reflected by the white hat back to the head and heating the head again. Black absorbs the infrared radiation from the head and releases it to the environment (that’s the reason why a lot of Beduin wear dark cloth). BTW. black is reflecting UV radiation from the sun but white does not not.

And I am wondering which temp. do we have in summertime under a hat.

Totally senseless but maybe here are some other crazy people ;-)

Best regards

Thomas from Germany

 

[deadlyhandsome]

Lots of variables so hard to draw conclusions, but interesting all the same. Hard to account for convection, conduction, and radiation differences as you have two heat sources and all three means of heat transference. You also need to account for air flow and insulation capabilities. Are we testing colors, materials, or something else? I’m no scientist or engineer (high Jim), but I find this interesting. At least you made an effort to quantify something we’ve all wondered about.

 

[Just Daniel]

That’s pretty cool. Maybe you can wear the hat with the thermometer on your head, or clipped inside the top of the sweatband? One recommendation: try fur felt, not wool.

I may give it a little thought, maybe even try with a digital BBQ thermometer I have. It might make a fun Coronavirus quarantine experiment!

Yesterday it was a boring day - I had too much time. So I did a test which temperature is under two different hats when the sun is shining.

I just put a thermometer under a white cheap paper hat (they call it panama but it is not) and a black wool hat.

Temperature in shadow was just 17 centigrade (63F) but full sun.

The temp. under the white was 34 centigrade(93F), under the felt 38 centigrade (100F)

I really was surprised how warm it is even when the ait temp. in shadow is quite low.

I am wondering which temp. would be when the hat is on my head – because my head is also producing heat. This would be interesting because black is absorbing infrared radiation and white reflects it. That means white reflects the IR from the sun and black absorbs it – what is one of the reasons it is warmer with the black one. BUT the heat of the head is also IR radiation and will be reflected by the white hat back to the head and heating the head again. Black absorbs the infrared radiation from the head and releases it to the environment (that’s the reason why a lot of Beduin wear dark cloth). BTW. black is reflecting UV radiation from the sun but white does not not.

And I am wondering which temp. do we have in summertime under a hat.

Totally senseless but maybe here are some other crazy people ;-)

Best regards

Thomas from Germany

 

[ThomasK]

That’s pretty cool. Maybe you can wear the hat with the thermometer on your head, or clipped inside the top of the sweatband? One recommendation: try fur felt, not wool.

I may give it a little thought, maybe even try with a digital BBQ thermometer I have. It might make a fun Coronavirus quarantine experiment!

Yes Daniel - corona is the reason I have time to do such stupid things ;-)
My thermometer is too big to put between head and hat and I don't have a fur felt. But maybe here are some other crazy people with plenty of time to do other tests.
Eg.

• black felt vs. white felt
• fur felt vs. wool felt
• felt vs. panama
• ...

 

[1967Cougar390]

I would think that in order for measurements to be accurate all the hats would have to be exactly the same. The only difference being the color. At work we used different colors of firefighting PPE. I have paperwork somewhere showing that black, tan, and yellow absorbed or reflected the same amount of heat. The difference was not so much the color and they type of fabric. Just a thought.

Steven

 

[Just Daniel]

Yes, the closer to exactly the same they are the better.

....but this is the Fedora Lounge, we’re at best shooting for an Ig Nobel here

I would think that in order for measurements to be accurate all the hats would have to be exactly the same. The only difference being the color. At work we used different colors of firefighting PPE. I have paperwork somewhere showing that black, tan, and yellow absorbed or reflected the same amount of heat. The difference was not so much the color and they type of fabric. Just a thought.

Steven

 

[1967Cougar390]

Yes, the closer to exactly the same they are the better.

....but this is the Fedora Lounge, we’re at best shooting for an Ig Nobel here

That’s a great prize, The Fedora Lounge IG Nobel prize. “In the Covid-19 hat temperature category, the winner is.....”

 

[ThomasK]

I would think that in order for measurements to be accurate all the hats would have to be exactly the same. The only difference being the color. At work we used different colors of firefighting PPE. I have paperwork somewhere showing that black, tan, and yellow absorbed or reflected the same amount of heat. The difference was not so much the color and they type of fabric. Just a thought.

Steven

Hey Steven, thanks a lot for this information. Is your info about helmets or hats?

White reflects infrared radiation (IR) but not ultraviolet (UV). Black reflects UV but not IR. That’s the reason why in theory both reflects and absorbs more or less the same amount of heat.

But for sun protection there is one big difference. If you wear a cotton shirt the black one reflects 97% of UV. The white shirt lets 40% of UV passing through and burning your skin (depends on the thickness).

But we are in the fedora lounge and this is more relevant for a trilby. I have no idea what this mean for felt or straw hats.

Best regards

Thomas

 

[1967Cougar390]

Hey Steven, thanks a lot for this information. Is your info about helmets or hats?

White reflects infrared radiation (IR) but not ultraviolet (UV). Black reflects UV but not IR. That’s the reason why in theory both reflects and absorbs more or less the same amount of heat.

But for sun protection there is one big difference. If you wear a cotton shirt the black one reflects 97% of UV. The white shirt lets 40% of UV passing through and burning your skin (depends on the thickness).

But we are in the fedora lounge and this is more relevant for a trilby. I have no idea what this mean for felt or straw hats.

Best regards

Thomas

Thomas, the information I was speaking about was in reference to the material that makes our firefighting protective jackets and pants.

This afternoon I will use my Fed IV’s and a thermometer to see what temperatures I come up with.

Steven

 

[Frunobulax]

Well, now you have me thinking about writing a test plan. I don't think we need to actually test under the hat while worn, as your body temperature can be treated as a constant, more or less. You would need to find as many different types of the same hat to gather as much data as possible under varying conditions. Once you can isolate the hats as being more or less constant, then put a sensor under it and test it under different temperatures.

Or perhaps I'm overthinking this in my zeal. We should be able to come up with a general heat transfer rate for felts and straws, and go from there.

 

[SteveFord]

Is the hat snug or loose, does it drop down around your ears or rest up atop the crown?
Big brim, little brim? Peter Cottontail, mink, genuine toe jam and belly button lint? The weight of the hat and density of the material?
Lots of variables other than color.
For me it's vented bowler or little shrimp brim fedora/tiny homburg in warm months, big fedora or antique homburg in the cold months, dark color for cold temperature, light color for when it's hot out.
I could be wrong, though.

From when I was doing industrial coatings years ago I was surprised to discover that silver parts cooled off faster than the black ones (using an IR gun when they came out of the oven). I figured that black would dissipate the heat faster but nope. That made me rethink doing motorcycle cylinders in black all the time.

 

[1967Cougar390]

Ok I had to change up a little because a standard thermometer did not register. I used a laser after wearing both hats outside for 10 minutes each. The outside temperature is 57 degrees Fahrenheit.

Tawny Fawn Fed IV:

Moonstoone Fed IV:

Steven

 

[AbbaDatDeHat]

Well, now you have me thinking about writing a test plan. I don't think we need to actually test under the hat while worn, as your body temperature can be treated as a constant, more or less. You would need to find as many different types of the same hat to gather as much data as possible under varying conditions. Once you can isolate the hats as being more or less constant, then put a sensor under it and test it under different temperatures.

Or perhaps I'm overthinking this in my zeal. We should be able to come up with a general heat transfer rate for felts and straws, and go from there.

More thinking to be done me thinks, Jim.
Full head of hair vs bald top?? No hair grease of course.
Have fun. Lol
B

 

[scottyrocks]

Identical hats on a human head still allow too many variables. You'd need a mannequin head to keep the 'wearer's' temperature constant.

Humidity also affects the wearer's perception of heat. For most people dry heat is more tolerable than a very hot, humid day.

Wind, even a breeze, will also affect a wearer's perception of heat.

Even the time of day will change the way heat is absorbed. Heat is usually at its height when the sun is at the top of its arc through the sky.

To get a truly accurate measurement of how color affects how hot the inside of a hat gets, the hat should be on a mannequin head in a controlled heated environment with a thermometer in the hat/on the head, and the thermometer should be able to send readings to a receiver outside the controlled environment so that the observer can record how the heat builds over a period of time. Then repeat with another hat that is identical, but of a different color.

Or when it's hot you can just put on a loosely woven straw and call it a day. hahaha

 

[Frunobulax]

Is the hat snug or loose, does it drop down around your ears or rest up atop the crown?
Big brim, little brim? Peter Cottontail, mink, genuine toe jam and belly button lint? The weight of the hat and density of the material?
Lots of variables other than color.
For me it's vented bowler or little shrimp brim fedora/tiny homburg in warm months, big fedora or antique homburg in the cold months, dark color for cold temperature, light color for when it's hot out.
I could be wrong, though.

From when I was doing industrial coatings years ago I was surprised to discover that silver parts cooled off faster than the black ones (using an IR gun when they came out of the oven). I figured that black would dissipate the heat faster but nope. That made me rethink doing motorcycle cylinders in black all the time.

There is a reason a perfect heat sink is called a Black Body, with an emissivity of 1.

More thinking to be done me thinks, Jim.
Full head of hair vs bald top?? No hair grease of course.
Have fun. Lol
B

Like @belfastboy, I'm throwing the humans out of the equation.

Identical hats on a human head still allow too many variables. You'd need a mannequin head to keep the 'wearer's' temperature constant.

Humidity also affects the wearer's perception of heat. For most people dry heat is more tolerable than a very hot, humid day.

Wind, even a breeze, will also affect a wearer's perception of heat.

Even the time of day will change the way heat is absorbed. Heat is usually at its height when the sun is at the top of its arc through the sky.

To get a truly accurate measurement of how color affects how hot the inside of a hat gets, the hat should be on a mannequin head in a controlled heated environment with a thermometer in the hat/on the head, and the thermometer should be able to send readings to a receiver outside the controlled environment so that the observer can record how the heat builds over a period of time. Then repeat with another hat that is identical, but of a different color.

Or when it's hot you can just put on a loosely woven straw and call it a day. hahaha

You don't even need the mannequin. Just make the surrounding conditions constant and measure under the crown of the hat.

I'm also not concerned about wind, etc. I want to isolate everything I can and determine the effects of the material on the temperature under the hat. After all, the question we're asking is about the hat. We already know all that other stuff.

 

[Rmccamey]

Once you get the process constant and repeatable, it would be helpful to set a common well-known standard. I would suggest a silberbelly RD Open Road or a Stratoliner. You probably need access to at least 3 that are of the same or similar vintage and configuration to get a good average.

Identical hats on a human head still allow too many variables. You'd need a mannequin head to keep the 'wearer's' temperature constant.

Humidity also affects the wearer's perception of heat. For most people dry heat is more tolerable than a very hot, humid day.

Wind, even a breeze, will also affect a wearer's perception of heat.

Even the time of day will change the way heat is absorbed. Heat is usually at its height when the sun is at the top of its arc through the sky.

To get a truly accurate measurement of how color affects how hot the inside of a hat gets, the hat should be on a mannequin head in a controlled heated environment with a thermometer in the hat/on the head, and the thermometer should be able to send readings to a receiver outside the controlled environment so that the observer can record how the heat builds over a period of time. Then repeat with another hat that is identical, but of a different color.

Or when it's hot you can just put on a loosely woven straw and call it a day. hahaha

There is a reason a perfect heat sink is called a Black Body, with an emissivity of 1.



Like @belfastboy, I'm throwing the humans out of the equation.



You don't even need the mannequin. Just make the surrounding conditions constant and measure under the crown of the hat.

I'm also not concerned about wind, etc. I want to isolate everything I can and determine the effects of the material on the temperature under the hat. After all, the question we're asking is about the hat. We already know all that other stuff.

 

[Frunobulax]

Once you get the process constant and repeatable, it would be helpful to set a common well-known standard. I would suggest a silberbelly RD Open Road or a Stratoliner. You probably need access to at least 3 that are of the same or similar vintage and configuration to get a good average.

We don't even need to do that. Just a table showing the heat transfer coefficient of felts based on thickness. You can overlay color correction standards on that, once generated. Once you have that, you know what level of heating will take place when you put it on your head.

As I've thought about this, I really think it's a pretty straightforward experiment. Just a lot of data generation so you have good numbers to go by.

 

[scottyrocks]

I'm still just gonna put on a well-ventilated straw when the time comes. haha

 

[Frunobulax]

My favorite engineering story:

A guy who lived in my dorm (we'll call him Tito, because that was his name) got a co-op job at GM Lordstown. During his stay, his manager came to him and asked him to design some sort of rack, I forget what, but a lead-bearing structure of some sort.

So Tito sits down at his desk, takes the estimated loads, and calculates the exact diameter of what sort of pipe would be needed to accomplish the job, utilizing all the engineering skills he has to derives such things.

He proudly takes his work to his boss, saying, that they need steel pipes of x diameter, etc, etc. His boss looks at his work and tells Tito, "That wasn't really necessary. Looks like the 3/4" pipe we have in stock will do."

 

[Rmccamey]

That's fine for precision, but few of us know the "thickness" or density of our felts (or have the equipment to measure it accurately) and having at least one of the "standards" being a hat commonly known and owned across most of us hat-o-philes would give us a common point of reference. In addition to a technical standard, I'm also thinking of a "practical" standard most of us can relate to.

We don't even need to do that. Just a table showing the heat transfer coefficient of felts based on thickness. You can overlay color correction standards on that, once generated. Once you have that, you know what level of heating will take place when you put it on your head.

As I've thought about this, I really think it's a pretty straightforward experiment. Just a lot of data generation so you have good numbers to go by.