I think it takes a fraction of a second, like this (painless, no heat demonstration) 0.25 seconds contact. Maybe even less.
The Global Cross-Hair Enigma that looks like Hair Dryer Burns
- Thread starter Mick West
- Start date
LilWabbit
Senior Member
Maybe in some cases, whilst not ignoring the variables of skin colour, hairdryer model and make safety (safe and high quality v. unsafe and low quality), hairdryer or heat gun, varying burn sensitivity in different parts of the body, varying burn sensitivity between people, etc.
LilWabbit
Senior Member
Way too short a clip to demonstrate a "lasting impact" let alone the effect of a hairdryer. Cannot really generalize anything from this experiment.
It's just demonstrating how long I think the contact would be, that's all.
I've burnt myself (accidentally) innumerable times with a wide variety of objects. A soldering iron used to be a common source of burns for me, at a certain temperature a very brief contact can be painless yet still singe the skin. It's burning a very fine outer layer. I'm tempted to do a brief experiment.....
Perhaps before I scar myself, though, a good first experiment would be to see how hot a hair dryer gets.
LilWabbit
Senior Member
Be careful, but hey, anything for science! Famous last words.
LilWabbit
Senior Member
Also, for better comparison, maybe you could test the hair dryer on spots similar to the OP pictures -- shoulder or nearby, knee or nearby regions towards the thigh, like @deirdre did. In the burn mark pics I didn't see lower arm like in your speed experiment but maybe I glossed over some pics too fast. Lower arm is also a tad riskier due to thinner fat layer.
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JMartJr
Senior Member.
Perhaps initial/practice tests on a porkchop or the skin on a chicken leg?
deirdre
Senior Member.
did you somewhat block the nozzle too? we're supposed to keep the hairdryer like 6 inches from head but i dont think people actually do that. i used to put mine right up on the brush (when using a round brush during the Farrah Fawcett days).
deirdre
Senior Member.
gummy bears? (this article about testing textiles against skin...not sure how that relates to burns)
Article: "There are also researchers that have carried out preliminary experiments with gummy bears for example". They also swell when they come into contact with water – exactly like human skin.
Ouch!
So I gave myself a slight "burn" with a thermocouple heated with a hairdryer. I'm using a thermocouple so I can control the temperature and don't actually damage myself. 75°C (167°F) is very hot, but not fry-off-your-skin hot.
First contact is 8 frames (0.27 seconds), second contact is 12 frames (0.4 seconds) and pressed a bit firmer. There was zero mark at first, but within a minute there was one distinct red line, and one faint one. Contrast-enhanced:
About 15 minutes later now, it's still visible, but faded a lot.
So I gave myself a slight "burn" with a thermocouple heated with a hairdryer. I'm using a thermocouple so I can control the temperature and don't actually damage myself. 75°C (167°F) is very hot, but not fry-off-your-skin hot.
First contact is 8 frames (0.27 seconds), second contact is 12 frames (0.4 seconds) and pressed a bit firmer. There was zero mark at first, but within a minute there was one distinct red line, and one faint one. Contrast-enhanced:
About 15 minutes later now, it's still visible, but faded a lot.
deirdre
Senior Member.
i think this one at 73.6-72.9c is more realistic as the first one you were all cognizant you were about to burn yourself. i think with something like a hairdryer it would take your brain a bit longer to process "what the...."
i wonder if moisture content matters, like the gummy bear article implies. if you go take a long shower and burn yourself again we can see if there is a difference.
I think I'll wait a while before more experiments. I'm wondering if the mark (now barely visible) will pop back into view tomorrow as my cells get around to doing whatever they do in such cases.i wonder if moisture content matters, like the gummy bear article implies. if you go take a long shower and burn yourself again we can see if there is a difference.
I think probably higher temperatures would be needed. I can't find much on hairdryer temperatures, just that the Dyson goes up to 100°C/212°F. I'd imagine cheap dryers with poor thermal regulation could go much higher - especially with dirty inlets.
deirdre
Senior Member.
yea. that's why i gave you a winky face. i dont actually want you to get gangrene over something you already debunked pretty damn fine.
deirdre
Senior Member.
i'm a little iffy about this model being available in 2013. am i reading the date wrong with those links?
Arm update. After about an hour the line was barely visible. But now, about 2 hours later, and after a shower, it's back. In fact both are
The top one (the briefer contact) was not at all visible.
There's no pain, maybe a very slight itch. The skin is very slightly raised. The small top mark seems more raised than the big lower mark.
If this was the full geometric pattern it would be very distinctive. Right now I'd just take it for two scratches.
The top one (the briefer contact) was not at all visible.
There's no pain, maybe a very slight itch. The skin is very slightly raised. The small top mark seems more raised than the big lower mark.
If this was the full geometric pattern it would be very distinctive. Right now I'd just take it for two scratches.
NorCal Dave
Senior Member.
You 'da man Mick!
Heading up to the woods looking for Bigfoot or trying to film the ISS, I'm your Huckleberry, but trying to burn myself with a blow dryer for science? I'll take a pass.
However, I did manage to give myself a pretty good, localized burn on the foot using a Plasma cutter, while stupidly wearing shorts and tennis shoes. A bit of slag dropped into my shoe and burned through the sock. While it hurt a bit at the time, I forgot for a day or so until the blister rubbed on my morning walk. I only remembered it because it did hurt a bit at the time and was in a strange place.
LilWabbit
Senior Member
The longer 0,4-second burn is still not as distinctive as the ones you posted here (granted I'm not considering possible image edits and camera differences in default images/settings). But one could already make the case that accidental burns are very possible because it takes less than half a second of contact with a 75°C-hot grill to generate a slightly raised skin burn of faint red colour on the forearm. But still not enough heat/contact time to match most of the burn pattern pics which would imply most are deliberate.
Maybe one full second of contact would produce a comparatively distinct pattern on the forearm, but be a tad more excrutiating to perform for science. The same duration of contact above the knee or around the shoulder might feel and look different.
I still think the point made by @Ann K on varying heat sensitivities and fat layers on different parts of the arm and leg is relevant. The one-second test may be easier to perform on the fattier and less sensitive bits of the upper arm or shoulder. In addition to being more comparable to the spots used in the pics.
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FatPhil
Senior Member.
Pinkness from accidental contact with hot sauna stones only lasted a couple of days - but that had the benefit of having a layer of sweat and condensed steam to boil off before searing could occur.I know my sauna elements glow, but there's a steep temperature gradient between them and the air, so I'm not sure what the surface temperature was. In contrast to that, the back of a hand making contact with the top of an electric oven included scabbing and lasted weeks.
I'd guess the most important thing is energy transfer, and therefore I'd guess that the damage is asymptotically proportional to the temperature to the fourth power times the contact time.
17 hours later:
Lower mark still visible.
The duration of the mark will relate to the severity of the burn. In the literature this is referred to as the "thermal insult", denoted Ω (omega). For a given object temperature this is most affected by the initial temperature of the skin, followed by the thermal conductivity (i.e the thickness and dryness of the epidermis). Fat thickness and local blood flow (perfusion) have little effect. See Ng, Prediction of skin burn injury. Part 2: parametric and sensitivity analysis.
They calculate a "damage rate" for various temperatures once the skin tissue gets to a certain temperature.
Different columns are from different researchers, with the newest (and probably more accurate) on the right (Takata and Wu)
I think the first row is a typo, and should be 40, not 49
Note a significant flip in the damage rate, at 50 it's 0.0000007 (basically nothing), then at 80 it's 55,800,000 (Ω/sec, I think). So 50 (122° is a very slow cooking - the lower end of sous vide cooking, where you can stick your hand in the water with no ill effects), but 70 and above is almost instant injury.
They then calculate burn thresholds - how long it takes to get a given Ω value for a given temperature. Ω relates to burn degree, with Ω = 0.53 being a first degree burn threshold, Ω=1 being second degree, and Ω being 1,000 (10^4) being third degree. Here we are mostly interested in first degree and second degree, as that's what is shown in the crosshairs examples. Mostly looking like first degree. But second degree is only slightly less than twice that (0.53 -> 1.0)
Remember, my experiment was about 73° to 75° during the contact. Kind of where things start to get dangerous. That's why I used a thermocouple.
- this assumes the object in contact with your skin does not lose temperature much during the contact, and I think the threshold here is Ω=1 (2nd degree burn)
This graph shows the effect if skin thermal conductivity (thickness and dryness), with three different values.
Logarithmic scale, the danger zone being to the left of 1. For 74°C the time to burn is between 0.2 and 2 seconds.
A hairdryer temperature of 100°C can result in a second-degree burn in under 0.1 seconds.
This will vary more because hairdryer grills are usually plastic, not metal. So don't hold a lot of heat, and so cool down rapidly in contact with a cooler object. But they obviously still cause damage.
So the bottom line here is that typical hairdryer temperature of 70°C to 100°C, combined with brief skin contact, are very consistent with the types of injuries seen here - especially in areas with delicate moisturized skin. And those injuries can be relative pain-free after the initial ouch - and hence the mark not noticed until a day or two later.
Lower mark still visible.
The duration of the mark will relate to the severity of the burn. In the literature this is referred to as the "thermal insult", denoted Ω (omega). For a given object temperature this is most affected by the initial temperature of the skin, followed by the thermal conductivity (i.e the thickness and dryness of the epidermis). Fat thickness and local blood flow (perfusion) have little effect. See Ng, Prediction of skin burn injury. Part 2: parametric and sensitivity analysis.
Article: Henriques' theory of skin burns is used for determining the spatial and temporal extent of tissue damage. The ranks of the effects of various factors were obtained. It was found that the highest ranked factor is the initial tissue temperature followed by the thermal conductivity of the epidermal layer. The effect of blood perfusion rate is ranked much below the combinations of other factors. The results from the present numerical experiment agree well with the results obtained by Palla. Sensitivity analysis of the critical exposure levels was also carried out and results are discussed. In this study, the effects of the various parameters on injury threshold were investigated. Again, the results indicate that the four parameters: thermal conductivity of the epidermis and dermis, convective heat transfer coefficient and initial tissue temperature, have a pronounced influence on assessing the burn injury threshold. It was also found that fat thermal conductivity and blood perfusion rate have no obvious effect on injury threshold.
They calculate a "damage rate" for various temperatures once the skin tissue gets to a certain temperature.
Different columns are from different researchers, with the newest (and probably more accurate) on the right (Takata and Wu)
I think the first row is a typo, and should be 40, not 49
Note a significant flip in the damage rate, at 50 it's 0.0000007 (basically nothing), then at 80 it's 55,800,000 (Ω/sec, I think). So 50 (122° is a very slow cooking - the lower end of sous vide cooking, where you can stick your hand in the water with no ill effects), but 70 and above is almost instant injury.
They then calculate burn thresholds - how long it takes to get a given Ω value for a given temperature. Ω relates to burn degree, with Ω = 0.53 being a first degree burn threshold, Ω=1 being second degree, and Ω being 1,000 (10^4) being third degree. Here we are mostly interested in first degree and second degree, as that's what is shown in the crosshairs examples. Mostly looking like first degree. But second degree is only slightly less than twice that (0.53 -> 1.0)
Remember, my experiment was about 73° to 75° during the contact. Kind of where things start to get dangerous. That's why I used a thermocouple.
- this assumes the object in contact with your skin does not lose temperature much during the contact, and I think the threshold here is Ω=1 (2nd degree burn)
This graph shows the effect if skin thermal conductivity (thickness and dryness), with three different values.
Logarithmic scale, the danger zone being to the left of 1. For 74°C the time to burn is between 0.2 and 2 seconds.
A hairdryer temperature of 100°C can result in a second-degree burn in under 0.1 seconds.
This will vary more because hairdryer grills are usually plastic, not metal. So don't hold a lot of heat, and so cool down rapidly in contact with a cooler object. But they obviously still cause damage.
So the bottom line here is that typical hairdryer temperature of 70°C to 100°C, combined with brief skin contact, are very consistent with the types of injuries seen here - especially in areas with delicate moisturized skin. And those injuries can be relative pain-free after the initial ouch - and hence the mark not noticed until a day or two later.
deirdre
Senior Member.
i can also still see upper mark. wondering too..how tan are you? it's summer in California, tan not only "hides" marks more but tan skin is typically warmer than cold skin. but if the hairdryer people just got out of the shower their skin might be a similar temperature?
i can't really follow the science you posted above: is it saying that hydrated, cold skin burns more? or dehydrated, warm skin? or does it not really answer that question?
So my large old, mid-priced, hairdryer went to 75°. I own two more.
First a Brookstone travel dryer, pretty old, inexpensive. It got to 100°C in 1 minute, 110°C in 2m30s, and 120°C at 2m50s
At that point I aborted the experiment as 120°C (245°F) is way too hot. Obvious immediate burn territory. In addition the grill was metal
Next, a much more expensive Dyson Supersonic. Well engineered and with an unusual design that pulls in air at the edged of the front nozzle before heating it and shooting it out the front. I only measured the exiting air temperature in the middle. This basically got to 80°C and then stayed there. Well regulated. It has a 100°C mode, but I did not try it.
So, the pretty obvious result - cheap hairdryers have poor (or no) thermal regulation and are more likely to produce burns - especially 2nd degree burns.
First a Brookstone travel dryer, pretty old, inexpensive. It got to 100°C in 1 minute, 110°C in 2m30s, and 120°C at 2m50s
At that point I aborted the experiment as 120°C (245°F) is way too hot. Obvious immediate burn territory. In addition the grill was metal
Next, a much more expensive Dyson Supersonic. Well engineered and with an unusual design that pulls in air at the edged of the front nozzle before heating it and shooting it out the front. I only measured the exiting air temperature in the middle. This basically got to 80°C and then stayed there. Well regulated. It has a 100°C mode, but I did not try it.
So, the pretty obvious result - cheap hairdryers have poor (or no) thermal regulation and are more likely to produce burns - especially 2nd degree burns.
Not much on the underneath of my arms. A very light tan compare to covered areas of skin.
Cold skin will burn LESS because it takes longer to reach the damage threshold (as it starts colder).
Hydrated skin will burn MORE as it has higher thermal conductivity. Like picking up a hot pan with a wet towel vs. a dry towel.
So warm hydrated skin (like just out of a shower, in a warm bathroom) is more likely to be damaged.
LilWabbit
Senior Member
Fat thickness might affect the sensitivity to pain and, by extension, the contact time with the hairdryer before the pain gets intolerable.
jarlrmai
Senior Member.
Pain is a device our body uses to convince us to avoid similar situations in the future, so usually painful events are memorable.
So from your experiments @Mick West do you think it's likely the burn needed to recreate the marks would be painless enough to not be memorable after a few days?
So from your experiments @Mick West do you think it's likely the burn needed to recreate the marks would be painless enough to not be memorable after a few days?
Yes, I had no pain after a few seconds. Obviously, some marks look more painful, but a lot do not.
deirdre
Senior Member.
it also kinda depends on how often it happens. if i had a dime for everytime i got myself with the curling iron, i could at least get one of those fancy grande coffees at Starbucks.
Mrs. West also tells of several misadventures with the curling or flat iron. There are numerous images online of such burns. Just not as interestingly shaped as hairdryer burns.
FatPhil
Senior Member.
Plastics generally have higher heat capacities than metals. It's the cooling down rapidly that's the problem, and metals do that more - they're dumping energy into your skin more quickly.
DavidB66
Senior Member.
Are you sure about this? My hairdryer is a very old, and fairly cheap, Braun Professional 1800, and has a metal grille. I'm not sure about the physics of cooling for metal v. plastic. Metal is generally a good conductor of heat, so when the dryer is switched off the hot grille will lose heat by conduction to the adjacent metal of the nozzle, which should be somewhat cooler. (I'm assuming that the grille, being immersed in the flow of hot air, will be the hottest external part of the dryer when it is 'on'.) I don't know whether metal would be better or worse than plastic at radiating heat.
As a crude experiment, I just tried running my Braun at maximum heat for 2 minutes, which I thought should be long enough to bring the temperature of the nozzle and grille to their max. I then switched it off and let it cool down for 1 minute (with ambient room temperature about 70 C.) At this point the external surface of the nozzle was still uncomfortably hot to the touch, so I did not risk touching the grille itself. After another 1 minute the external surface of the nozzle was merely warm, so I touched the grille with a finger knuckle, and then the more sensitive finger tip. At this point the grille was just warm, and not much hotter to the touch than the external surface of the nozzle. Certainly not hot enough to cause pain or injury to normal skin. If this is representative, a dryer would not cause burns if it has been switched off for more than a few minutes.
Incidentally, I think it would be very difficult to burn oneself with the hot grille, either deliberately or accidentally, while the dryer is 'on'. The blast of hot air (at least with my dryer) is strong enough to make it difficult to press the nozzle against the skin, and hot enough to make it very painful to try it.
Yeah, I was thinking more of metal as being a dense material with high thermal conductivity. But you and @DavidB66 are correct, they DO hold a lot of heat.
Heat Capacity by mass: (J/(Kg C)) https://www.engineeringtoolbox.com/specific-heat-solids-d_154.html
- Plastic: 1.67
- Steel 0.49
- Plastic: ~700
- Steel: ~2400
Heat Capacity by volume works out about the same, I think.
- Pastic: 1.67*700 = 1169
- Steel: 0.49*2400 = 1176
And most of the examples we see are of plastic grills. Probably safer, though, because of the much lower thermal conductivity.
https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html
https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
Theremal Conductivy W/(m K)
- Plastic: 0.33 - 0.51 (Polyethylene)
- Steel: 14 .3 (Stainless)
Granite
New Member
I'm a little disappointed that so much attention was given to the very obvious self inflicted burns by hair dryers, and not the fact that vallee has apparently ceded whatever credibility he had left over this. He uses transparently foolish logic, while trying to cater to a demographic of believers - why? What happened to him? I don't remember him ever acting this Alex Jones-like.
I do remember his ufo conclusions decades ago approaching the correct source - the military - but never coming out and saying it. I felt he was likely a shill for the military due to that, but this Atlantean crap isn't even trying. Is it something like dementia or is he simply showing his true colors finally?
I do remember his ufo conclusions decades ago approaching the correct source - the military - but never coming out and saying it. I felt he was likely a shill for the military due to that, but this Atlantean crap isn't even trying. Is it something like dementia or is he simply showing his true colors finally?
deirdre
Senior Member.
@Mick West i forget where that database you were looking at is in this thread. are these mark receivers generally women?
i ask because every comment about pain and how people would notice, reminds me that women pluck and wax hairs off their upper lips*, rip their bikini area hair out with wax (i never tried that one myself), and birth babies.
*waxing the upper lip is way more painful then a curling iron burn. esp the tinyist hairs right up against your nostrils. you guys wnt to experience "ouch", try that one.
i ask because every comment about pain and how people would notice, reminds me that women pluck and wax hairs off their upper lips*, rip their bikini area hair out with wax (i never tried that one myself), and birth babies.
*waxing the upper lip is way more painful then a curling iron burn. esp the tinyist hairs right up against your nostrils. you guys wnt to experience "ouch", try that one.
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