Product Information
Manufacturer: Hot Chillys
Manufacturer URL: http://www.hotchillys.com
Year of Manufacture: 2004
Country of Manufacture: USA
Style: Geo Thermal
Model: Mens Zip-T top HC4733
Size: Large Top, Large Bottoms
Material: 7 oz (198 g) flat back textured knit, 51% Bio-Silver nylon, 49% MTF polyester
Color: Charcoal
Listed weight: none listed
Actual weight: 7 oz (198 g) Top
Actual weight: 7 oz (198 g) bottoms
MSRP: Not listed
December 4, 2004

Field Report

I will be reporting in two parts.  The top and bottoms where tested at different times and in different conditions.

Top:

    The Geo Thermal top was tested on a few day hiking trips in the San Bernardino Mountains around Devil's Punchbowl and Juniper Flats, south of Apple Valley, California.  Elevation ranged from 3000 ft (914 m) to 5500 ft (1676 m).  Temperatures ranged from 40 F (4 C) to 60 F (16 C).  On my trip to Devil's Punchbowl, I encountered light rain.  During both day hikes, the top was used as my main layer against my skin.  The warmth of the top worn with no other layers while at rest breaks is at the 60 F (16 C) mark for me.  As the temperature dropped, I needed to add a layer to stay warm.  While doing physical exertion, hiking, I felt comfortable down to 45 F (7 C) with the Geo Thermal top as my only layer.
    I found the Geo Thermal top to be comfortable as my next to skin layer.  I had initial concerns about the zipper irritating my chest and neck, but disregarded these after wearing it on my hikes.  There is no fabric flap between the zipper and skin.  Even though the zipper lies against my skin, I didn't experience any chaffing or irritation.  I do not have a hairy chest, so I did not have to worry about the zipper pulling chest hair during the field tests.  I was able to open the zipper when I needed to vent as I pushed myself along the trail to keep from over heating.  I could then zip it back up when I stopped for a break.
    The top helped keep me cool while hiking by allowing my perspiration to be wicked along the fabric and allowed to dry faster.  I could see the capillary action of the material working along my shoulders best.  As I was hiking with a day pack on, I started sweating under the shoulder straps of my pack.  I observed the sweat spreading out along the fabric next to the shoulder straps.  I feel this helped me from chilling once I took my pack off at rest breaks.  I would feel an initial chill from the wind hitting my previously covered shoulders and back, but I timed this to last no more than 30 seconds.
    The fabric and stitching continue to retain their shape.  I have noticed a few "pills" on the fabric from where my shoulder straps sit.  I will keep an eye on this as I continue my long term testing.  I have snagged the sleeve on a small branch along the trail, but I can see no sign of this happening from examining the material.
    The top has retained its soft, comfortable feel.  My arms were able to swing freely without the sleeves riding up onto my forearms.  The top stayed tucked into my pants while hiking, but I plan on testing how well it stays tucked in while rock scrambling in Joshua Tree National Park.
The Bio-Silver material within the fabric appears to work under day hiking conditions.  Most other synthetic fabric shirts that I wear while hiking collect a funky smell rapidly, whereas, the Geo Thermal top did not have any bad smell from these very sweaty day hikes.

Bottom:

    I have not had the need to use my Geo Thermal bottoms on any hikes during the field report phase of testing. However, I was able to use them over two days at home during a very unexpected snow storm days before Thanksgiving.  The elevation at my house is 3064 ft (934 m).  The temperature during the two day snow storm were between 20 F (- 7 C) and 30 F (- 1 C).  I wore the bottoms under a pair of denim jeans while playing in the snow with my wife and children.  As my denim jeans became wet from melting snowballs, I did not feel cold from them.  My opinion is that the Geo Thermal bottoms wicked some of the moisture from my sweat and warmed the melting snow before it came in contact with my skin.  I cannot prove this scientifically, just my opinion.  My legs were comfortably warm.


Planned long term testing:

    I have hikes planned for Joshua Tree National Park before and after Christmas.  These trips will range in temperature between 10 F(- 12 C) and 50 F (10 C).  I will have need of a light base layer for these hikes.  I plan on using the top and bottoms in conjunction with my sleep system on sub freezing nights in the desert.


Reviewer

Name: Scott Downard
Age: 30
Gender: Male
Height: 6 ft (1.83 m)
Weight: 205 lb (93 kg)
Email address: rookthepagan@verizon.net
City, State, Country: Apple Valley, California, U.S.
Date: December 4, 2004

Backpacking Background
    As a teenager, I did a lot of backpacking and hiking with the Boy Scouts.  After I turned 18 and I left the Scouts, I abandoned backpacking.  Ten years later, when I was 28, I started getting interested in backpacking again.  I started buying gear to replace the old stuff from my teenage years.  I hike in the local mountains and desert areas.  I hike mostly in the spring and fall in moderate weather.  Some rain is encountered.  I primarily do day hiking and short term (i.e. one to four nights) backpacking excursions with some five day trips.  I tend to hike fast while backpacking.