Moisture buildup underneath MBP

[thatguysmells]

I use my 13" MBP in bed on my lap while on top of a large hard cover book. After I use the laptop for about 20 minutes or more, I lift up the computer and the blanket is wet. Under the book is wet and around the lap top is wet. Is this condensation building up? The air temperature in my room isn't even that cold. This is really strange but condensation is the only thing I can think of. The problem doesn't seem to occur on a desk or table. It only happens when I use the laptop on my blanket. I'm not sure the fabric of the blanket but it kind of feels like a polyester.

 

[MrCheeto]

Somebody is sweaty or didn't leave the bed spread on the line long enough

 

[thatguysmells]

Somebody is sweaty or didn't leave the bed spread on the line long enough

Ya no. Not the problem. Does anyone have a real answer?

 

[miles01110]

It doesn't have to be "cold" for things to condense. That's almost certainly what's going on.

 

[mkrishnan]

I don't understand the physical arrangement of the things involved... is it like this?

MBP
----
book
----
blanket
----
your lap

?

And where is the moisture? Both between the MBP and the book, and between the book and the blanket? What kind of environment do you live in? It seems hard for me to imagine that the MBP's surface is generating that much condensation, that it not only gets the MBP wet but also the water spills over the book and gets the blanket wet, too....

 

[thatguysmells]

I don't understand the physical arrangement of the things involved... is it like this?

MBP
----
book
----
blanket
----
your lap

?

And where is the moisture? Both between the MBP and the book, and between the book and the blanket? What kind of environment do you live in? It seems hard for me to imagine that the MBP's surface is generating that much condensation, that it not only gets the MBP wet but also the water spills over the book and gets the blanket wet, too....

Ok the set up is this:

MBP
Book
Blanket
lap

^In that order.

The moisture is appearing underneath and around the book. So moisture between the book and the blanket and around the book. If I don't use the book, the moisture occurs between the MBP and the blanket.

I should note that my lap is NOT SWEATY AT ALL. And the room temp is not that cold, windows shut.

If it is condensation, why doesn't it occur on a desk in the same room? The blanket seems to be the culprit causing the condensation. Why would a blanket do that?

 

[moel]

Where the hell are you for the air to be THAT humid?

 

[thatguysmells]

Where the hell are you for the air to be THAT humid?

I live 2 blocks from the ocean. And my room faces the ocean. La Jolla, CA.

But, like I said, my window is shut! Is the air inside my room still moist even if the window is shut?

 

[square one]

does "thatguysmell" because he wets the bed?

 

[thatguysmells]

Where the hell are you for the air to be THAT humid?

I just checked local weather. Humidity is 59%. Air temp is 64.8. Is that a high humidity?

http://www.wunderground.com/US/CA/La_Jolla.html

 

[Vanarak19]

I just checked local weather. Humidity is 59%. Air temp is 64.8. Is that a high humidity?

http://www.wunderground.com/US/CA/La_Jolla.html

100 is high

 

[miles01110]

If it is condensation, why doesn't it occur on a desk in the same room? The blanket seems to be the culprit causing the condensation. Why would a blanket do that?

Because a blanket has decidedly more surface area on which moisture can build up than most desk materials. It also has different insulation characteristics.

 

[mkrishnan]

I just checked local weather. Humidity is 59%. Air temp is 64.8. Is that a high humidity?

http://www.wunderground.com/US/CA/La_Jolla.html

Hmm, that's a pretty low humidity, although the air is cool enough that there's a big differential between the Mac's temperature and the air (the combination causes a lot of condensation).

If the moisture is more between the book and the blanket than it is between the Mac and the book, I would go back to suspecting sweat... honestly, in Northern Florida (which is much, much more humid than SoCal), getting that kind of condensation off a metal notebook isn't something I've heard of much.

 

[thatguysmells]

Hmm, that's a pretty low humidity, although the air is cool enough that there's a big differential between the Mac's temperature and the air (the combination causes a lot of condensation).

If the moisture is more between the book and the blanket than it is between the Mac and the book, I would go back to suspecting sweat... honestly, in Northern Florida (which is much, much more humid than SoCal), getting that kind of condensation off a metal notebook isn't something I've heard of much.

My legs and lap are completely dry. No sweat at all. No noticeable moisture in the room either.

 

[velocityg4]

I don't really see how the laptop could be getting condensation at all. Since when running its surface temperature should be greater than the ambient temperature. Is the book in a freezer before being placed under the Macbook so that the book allows for condensation?

 

[thatguysmells]

I don't really see how the laptop could be getting condensation at all. Since when running its surface temperature should be greater than the ambient temperature. Is the book in a freezer before being placed under the Macbook so that the book allows for condensation?

Nope. Everything is room temperature.

 

[DesignerOnMac]

I just checked local weather. Humidity is 59%. Air temp is 64.8. Is that a high humidity?

http://www.wunderground.com/US/CA/La_Jolla.html

Since the temperature is around 65 degrees, have you tried the combination without the blanket?

Have you considered getting a laptop stand with a fan inside?

The condensation is not coming from the computer. If the blanket is polyester, then it is trapping any moisture that is coming off your skin. Just because your not sweating does not mean moisture from your body isn't happening. Especially since you say that this does not happen on your desktop.

 

[thatguysmells]

Since the temperature is around 65 degrees, have you tried the combination without the blanket?

Have you considered getting a laptop stand with a fan inside?

The condensation is not coming from the computer. If the blanket is polyester, then it is trapping any moisture that is coming off your skin. Just because your not sweating does not mean moisture from your body isn't happening. Especially since you say that this does not happen on your desktop.

If that were the case their would be moisture under the blanket where it contacts my skin. Which there is not. The moisture is on top of the blanket.

 

[drambuie]

If that were the case their would be moisture under the blanket where it contacts my skin. Which there is not. The moisture is on top of the blanket.

That last resonse explains it. Human skin is always evaporating moisture, even if it's dry to the touch. In your case, the moisture penetrates right through the blanket, but condenses under any barrier on top of the blanket, whether a book, or laptop. If you put a plastic bag on your lap, below the blanket, I would suspect that the underside of the bag would get moist. If you have no heat on in your room, the humidity level in the room is probably high enough to prevent evaporation when the moisture hits a barrier.

In colder climates requiring insulation, a plastic vapor barrier is placed between the interior wall material and studs. This prevents moisture from penetrating the insulation and condensing on the inside of the outer wall, resulting in soaked insulation, and possible wood rot.

 

[Magoo123654]

Previous two are correct. If you want a more technical explanation of moisture without sweating, look up: Transepidermal water loss (TEWL) - water passing out of the epidermis (skin) that is passive, that is, not related to sweating.

I have a higher TEWL than a lot of people, so I have the same issue with moisture under my laptop when it sits on my lap, even in winter with a blanket between.

 

[spiderman0616]

Where the hell are you for the air to be THAT humid?

I know you weren't asking me, but I live in the upper midwest. We get very humid summers here, and I've experienced things like what OP is describing.

 

[Raebo]

Are you doing something intensive on your MacBook?

Live in Georgia. Usually read for a half hour on MacBook Pro 14 at night while laying in bed.
Temp has been about 85 and humidity around 80 outside when I hit the sack.
Temp in bedroom is 73 and humidity around 55 inside.
Have MacBook on top, light blanket, then sheet, then me.
Never notice moisture on MacBook or anything else.

 

[DavidChoux]

Didn't someone else here have something like this happen?

Or maybe is was another forum. But it was a picture of their mac literally in a pool of water and they claimed they spilt nothing and it just simply came from the laptop.

As far as I remember some commenters pointed to the battery potentially being the problem.

I don't think it's condensation. I'm living in Asia at the moment and it's very hot and humid in summer here. Even when I work outside for then come inside to cold AC I've never seen a drip of condensation.

 

[TinyMito]

Sure it's not your lap legs are sweaty?

 

[YaBoiD]

Happened to me too. Rested on my lap on with blanket in between. Casually browsing the internet. Far from anything that would tax the processor. After about an hour, when I lifted it up, realized condensation had settled on the bottom. Temperature inside my home was in the high 60’s at the time. Haven’t been able to replicate the issue on a hard surface.