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Mylar – isn’t it good for ANYTHING?


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Home Forums Gear Forums Gear (General) Mylar – isn’t it good for ANYTHING?

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #3721071
    Daniel H
    BPL Member

    @daniel0o0

    As far as I know this material has only been acknowledged by the forum as useful for cooking food. Aside from this I have been educated in its actually very useful hammock underquilt service (when the mylar is tied neatly below the hammock) because with the gap possible between the hammock and mylar the hammock isn’t getting wet. So other than food and a hammock I would like call out and ask: really, are these the only things this material is good for due to its devastating side-effect of getting sopping wet? Or are there any other ways to make use of this lightweight thermal material where its sopping wetness will not destroy its benefits? And here is my main question I would like to ask the forum: is it possible that one useful way to use mylar would be on the leg portion of my foam sleeping pad? With the idea that because the legs produce less heat than the torso perhaps the condensation would be a lesser problem? Or perhaps other factors would allow for mylar to be used just on the leg section of the foam bedding? What do you think?

    #3721080
    Sam Farrington
    BPL Member

    @scfhome

    Locale: Chocorua NH, USA

    Mylar is to me the super light clear plastic that provides the outer walls of DCF material.  Sort of like saran wrap, but even lighter with a different composition.  Guess you have some in a quite different form.

     

    #3721103
    Daniel H
    BPL Member

    @daniel0o0

    Yes I mean the mylar like the emergency blanket stuff. It has great thermal properties and is very light. I found the forum search bar now so I can better see where mylar is talked about here. And even though I can’t read all of the many posts about, skimming through still reveals that it is not commonly used for anything because of course it get sopping wet from condensation. I haven’t actually left on my trip to Europe yet and I am just finishing up my gear decisions and purchases. My bed is a Zlite SOL cut in half so I can double it under my torso and I sandwich a 1.5″ foamie between them. My legs don’t need a closed cell foam because they are light enough but they need to be elevated enough to match my elevated torso so another 1.5″ foamie bit is used for my legs. However I would like to know if putting mylar on that leg section is a probably worthwhile idea, a probably terrible idea or if another idea might be good to create some thermal properties under my legs.

    #3721104
    Monte Masterson
    BPL Member

    @septimius

    Locale: Changes Often

    I find the Mylar works great for pairing up with a stand alone 7 oz silk bag liner in summer temps that don’t dip below 55*F. The one I use measures 84″ X 54″ and weighs 1.8 oz. I deploy it when the nights are a little cooler than what the silk liner and windjacket together can handle. I simply place the Mylar on top. Makes a HUGE difference in warmth. Of course it doesn’t breathe, but as part of an SUL pack weight the Mylar can save the night….and for only a measly 1.8 oz weight penalty.

    #3721150
    Diane “Piper” Soini
    BPL Member

    @sbhikes

    Locale: Santa Barbara

    The way you state your question sounds more like you have a solution (mylar) and are looking for a problem it can solve. Sometimes going ultralight means asking yourself, “do I really need this”?

    If you want additional warmth under your legs, perhaps get a full-length foam pad.

    #3721151
    Daniel H
    BPL Member

    @daniel0o0

    Thanks Monte I believe I fleetingly guessed Mylar might be a lesser condensation problem in less colder weather. Very good thank you.

    #3721152
    Daniel H
    BPL Member

    @daniel0o0

    This post was reported by our community for violating our forum guidelines, reviewed by our moderators, and has been removed. – MK

    #3721153
    Bruce Tolley
    BPL Member

    @btolley

    Locale: San Francisco Bay Area

    @ Monte

    “I simply place the Mylar on top.”: Are you referring to the space blankets with the reflective side?  So you place the reflective side toward your body?

    #3721154
    Daniel H
    BPL Member

    @daniel0o0

    [edited -MK]
    …So I’m out. And wishing you the best travels good bye.

     

     

    #3721155
    Sam Farrington
    BPL Member

    @scfhome

    Locale: Chocorua NH, USA

    Daniel H,
    Very sorry to see you go.  But thank you for the clarification that you were referring to the emergency blanket stuff.   A well known cottage tent maker or yore tried bonding mylar to the inside of his single wall tents in order to reduce condensation.  Forget if he had the silvery side or the colored side facing out.  Unfortunately, condensation persisted, and the mylar wouldn’t bond well.  It wasn’t till recently with DCF (formerly Cuben) that a process was developed to use use autoclave technology to bond mylar to make ‘fabric’ for tents and other gear.

    I think you would get some additional warmth under the legs and feet with the mylar facing up to reflect body heat.  But then there is the problem of keeping it in place, and condensation, because the material does not breathe, as you pointed out.  Since I empty my pack completely and disconnect the top storage flap containing small items, and the pack has a mesh backband (like most Ospreys), I just put it under the legs and feet with the net facing up.  There may be condensation on the inside back cover that is waterproof, but that does not reach up through the mesh backband, which stays dry.  And it saves the need for one more item in the kit to deal with colder situations.

    You could make something with open cell foam with a waterproof breathable bottom and a fully breathable top. Indeed, that’s what I did to make sleeping pads for my dogs, only with Primaloft insulation and a stiffener to keep the pads in place.  But without making a project of it, I’d go to a store like Jo-Anne’s fabrics and look for some foam sheet that is open cell, but stiff enough to add some warmth.    Or you might find some other breathable material there that is easy to roll up and pack, but with some insulative value and enough body to stay in place under the legs and feet.  Good luck!

    #3721183
    Monte Masterson
    BPL Member

    @septimius

    Locale: Changes Often

    Upon a second look the emergency blanket I’m using is actually “Aluminized Non Stretch Polyester”. It’s the same on both sides. I don’t know how it differs from mylar, but it definitely works well. Sure, due to the fact it doesn’t breathe a bit of condensation builds up underneath, but at least I’m able to stay warm enough to sleep. The silk liner and my synthetic clothing dries out fast in the morning so it’s no big deal. The blanket is more for when the temps dip a tad lower than what I predict my liner and windjacket can handle. The liner and emergency blanket together weighs 8.8 oz, almost 5 oz less than my 50 degree Apex quilt, yet I wouldn’t try to go below 53 degress with the liner, windjacket and emergency blanket combination.

    https://www.walmart.com/ip/Ozark-Trail-82-5-x-52-Aluminized-Non-Stretch-Polyester-Emergency-Blanket/336932569

    #3721345
    Bruce Tolley
    BPL Member

    @btolley

    Locale: San Francisco Bay Area

    For short trips, I often use what I think is a mylar very light e-blanket underneath me with the reflective side facing up to reflect radiating heat from my body back at me. Since it if flimsy, and prone to tearing, I usually dont take it on longer trips for this purpose.

    But Monte describes an interesting application, wrapping it outside the top of his very lightweight summer kit.  So I suppose the relective side(s) reflect back some of his radiated heat, but perhaps at the same time the layer of fabric marginally increases the air gaps around his body to aid in reducing loss of heat through radiation.  But since this is summer and as the evening progresses depending on local topography there is often a katabatic effect that moves air along the ground at speeds of 1 to 5mph, I wonder if there is also a benefit from the extra layer of wind protection, protecting heat loss from convection.  Adding up all these effects could yield the huge benefit.

     

    #3721363
    Rex Sanders
    BPL Member

    @rex

    Locale: California

    From Wikipedia:

    BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties, and electrical insulation.

    A variety of companies manufacture boPET and other polyester films under different brand names. In the UK and US, the best-known trade names are Mylar, Melinex, and Hostaphan.

    Biaxially oriented PET film can be metallized by vapor deposition of a thin film of evaporated aluminium, gold, or other metal onto it. The result is much less permeable to gases (important in food packaging) and reflects up to 99% of light, including much of the infrared spectrum. For some applications like food packaging, the aluminized boPET film can be laminated with a layer of polyethylene, which provides sealability and improves puncture resistance. The polyethylene side of such a laminate appears dull and the boPET side shiny.

    Dozens of applications listed.

    — Rex

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