Reviews > Hydration Systems > Bottles > GSI Outdoors 16oz Lexan Flask > Owner Review by Andrew Mytys > Owner Review by Andrew Mytys

Tester's Biographical Information:

Reviewer: Andrew Mytys Email: amytys@gmail.com Homepage: Andy's Lightweight Backpacking Site Location: Michigan Age: 33 Height: 6'1" (183 cm) Weight: 185 lbs (84 kg) Shoe Size: Mens 10 (US); 9 (UK); 43 (EU); 280 (JP/KR)

     Backpacking Background:

I live in Michigan and have been hiking seriously for 15 years, although I've camped since I was 6 years old. I consider myself a lightweight hiker. I carry the lightest gear I can get my hands on which will provide a comfortable wilderness experience and adequately support the goals of my trip. Unless my goals are time/distance oriented, my pace is always slow. I rarely exceed 1.5 miles (2.4 km)/hour. I rest frequently, hike long days, and enjoy whatever nature throws my way.

Product Information:

Manufacturer: GSI Outdoors Item: GSI Outdoors 16 oz Lexan Flask Year of Manufacture: 2002 MSRP: $9.95 Volume: 16 fl oz (475 ml) Listed Weight: 4 oz (113 gm) Weight as delivered: 4.2 oz (120 gm)

Field Experience:

I have owned the GSI Lexan Flask for three years. During that time, it has accompanied my on most backpacks and dayhikes, year round. I would estimate I have carried it on 40 overnights in addition to a large number of dayhikes.

Description:

The GSI Outdoors 16 oz Lexan Flask is a compact and durable flask made for carrying liquids. It has a capacity of 16 oz (475 ml), with a handy 1 oz (30 ml) "shot" cap. The flask has a flat profile that's comfortable when held in my hand, and it discretely fits into deep pant and jacket pockets. The Lexan flask is transparent gray in color, making it easy to determine the level of liquid inside. The flask seals tightly and is leak-proof, thanks to a rubber gasket that can be found on the inside of the cap, at the base of the threads.

Lexan:

The GSI Outdoors Flask is constructed of Lexan - a thermoplastic, polycarbonate resin, made by General Electric's plastic division. Lexan has some fantastic properties that make it advantageous for use in the construction of water bottles. To start, Lexan is durable - ounce for ounce, it is stronger than steel. Lexan remains strong and shatter resistant whether exposed to very hot or very cold temperatures. This means that liquid held in the flask can be frozen or, conversely, that boiling water can be poured directly into the flask without the container becoming soft, changing shape, or developing holes or cracks in its structure. Lexan is rated durable in temperatures down to -40° F (-40° C). It is resistant to staining, odors, and absorbing tastes from previously held contents.

Personal Observations:

At 4.2 oz (120 gm) in weight, there are lots of lighter solutions for carrying around 16 oz (475 ml) of water. Why, you might ask, would a "lightweight backpacker" such as myself carry a relatively heavy container when a simple 1 oz (28 gm) plastic pop bottle would suffice?

The reason I have resolved to add this piece of gear to my packload lies in its heat-resistant properties, and in the shape of the flask itself. In combining these two features, I have found that the GSI Lexan Flask makes for an excellent hot-water bottle. This, in turn, has enabled me to carry a much lighter sleeping bag than I would without the flask, and the Lexan container now doubles as additional warmth in times when the weather surprises me with much colder temperatures than were forecast. No matter what the season, the Lexan Flask can be used to augment my sleeping bag's comfort range by as much as 15°F (8°C).

In the "3-season", this translates into my carrying a 45°F (7°C) bag that weighs just under one-pound (450 gm). Should temperatures drop to a point where I am uncomfortable, I simply pour the contents of my GSI Flask into a pot, bring it to a boil, then pour the water back into my flask and place it into my sleeping bag. I find that a flask filled with boiling water is too hot to the touch, so I pull out a liner glove or sock, slide the hot flask inside, and then either put this onto my chest or between my legs. Between the heat trapping capabilities of my sleeping bag and my own body heat, tests have shown that the Lexan flask will remain HOT for over two-hours. After this period of time, the flask can be removed from the protective liner and then be placed directly onto the skin, allowing it to continue its warming effect.

Eventually, the flask no longer delivers any effective warmth but, by this time, it is morning and time to get moving anyway. The contents of the flask are still warm and drinking from it can provide additional comforts.

Of course handling water in the middle of the night in close proximity to a down bag can be risky. Personally, I've had no "accidents" to date with the system I've described. I have never felt that I've been fortunate in this regard - the opening to the flask is wide enough to use confidently, even when handling boiling water. Add a little caution to the mix, and I get by even while half asleep and not wearing my glasses. The cap on the flask provides a secure seal, and the Lexan strength means that I am not worried about leakage should I roll over onto it while sleeping.

In winter conditions, the GSI Lexan Flask can continue to be used in warming the inside of a sleeping bag. I've found that my feet can get really chilled after being out in the cold all day - as my feet sweat, the socks in my boots get damp, and this in turn can cause circulation issues in my feet, especially when I've arrived in camp and taken my feet out of my boots. Typically, I remove the damp socks from my feet, let my feet air out and dry for about a minute (dry winter air evaporates moisture from my feet quickly), and then put a dry pair of 200 weight fleece socks onto my feet. This is followed by a pair of down slippers, and I then place my feet into my sleeping bag. At times, my feet still feel cold and this is when I use the GSI Lexan Flask. I fire up the stove, turn some snow into boiling water, fill my flask, and then, thanks to the flask's slim profile, I can slide both the flask and my foot into my slipper (for shoe size, see biography).

Many hikers like to dry damp clothes in the winter by positioning them against their skin or in the footbox of their sleeping bag while they sleep. I'm not a proponent of this system, as any drying that occurs increases the amount of water vapor that the sleeping bag has to manage - the result is often a loss in the sleeping bag's loft and heat-trapping capabilities. As luck would have it, snow melting is a time consuming task. As each pot of snow comes to a boil, I rotate the water into my GSI Lexan Flask and start melting the next batch of snow. While I wait for the snowmelt to boil, I take the hot flask and place it into my liner sock. I watch the steam rise into the air as the sock dries on contact. Any dampness in my thin, Coolmax liner socks dries in less than a minute. I repeat the process with my thicker, ragg wool hiking socks. As the water in my pot comes to a boil, I pour the water from my flask into a larger water container, then pour fresh boiling water into the flask in order to maintain drying efficiency.

Of course, a hot GSI Lexan Flask can be used to dry more than socks. Often times, I find that the shell of my jacket or sleeping bag footbox is damp or even wet. A flask filled with boiling water can be comfortably held by its neck and moved about over the wet area in a quick, circular motion until it is dry (see image, above). A flask filled with boiling water does tend to be hot, so I keep the bottle moving to mitigate any risk of melting the synthetic materials. This "backcountry iron" technique works like magic, and in a matter of minutes my equipment is dry once again.

The advantages of the GSI Lexan Flask continue into the summer, when I place the flask filled with water into the freezer before a short trip. Then, while on my dayhike, I cool myself by pressing the Lexan flask against my neck or under my shirt, and sip ice water as the frozen flask slowly thaws out.

There are other Lexan water bottles on the market, but I've found their rounded shapes causes them to roll around at will. Their wider profile also means they can't slide into the tight spaces I tend to place my flask. For me, the GSI Lexan Flask is a clear winner!

Durability:

Aside from a few scratches, the GSI Lexan Flask remains good as new. The rubber gasket ring inside the cap continues to function - the cap provides a tight and leak-proof seal.

Recommendations For Improvement:

• The GSI Lexan Flask has an edge from the production mold going around its parameter. The manufacturer would do a great service in delivering a product that had a smooth edge all around. My flask had a rough bottom, a characteristic that I discovered when I heard and felt it catch against the inner lining of my Western Mountaineering sleeping bag. Thankfully, morning and post-trip inspections verified that there was no damage done (whew). Before considering using the flask as an in-bag hot water bottle, buyers should be prepared to take some fine-grade sandpaper to the bottom of the flask, and any other rough spots found, in order to smooth out jagged areas.
  
  
• The manufacturer could include a message on the packaging warning users that the flask's cap contains a rubber gasket ring inside, and that at times this ring can work its way loose. During those times when the flask was sealed with boiling water inside and then allowed to cool, I noticed that the gasket either adhered itself to the top of the flask's opening or slipped loose on the inside of the cap while it was being opened - I've even had the gasket fall out of the cap. Fortunately, the first time that the gasket worked its way loose I noticed it, and I've since gotten into the habit of verifying that the gasket is in its proper position, at the base of the cap's threads, before closing my flask. Testing indicates that a missing or improperly installed gasket will result in the flask leaking. As I routinely have the flask filled with scalding water next to my skin, it's important for me to verify that the gasket is installed correctly before I screw the flask's cap on.

Reviews > Hydration Systems > Bottles > GSI Outdoors 16oz Lexan Flask > Owner Review by Andrew Mytys > Owner Review by Andrew Mytys