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Reviews > Clothing > Shirts > Sitka Gear Core Zip T > Test Report by Ray Estrella

Sitka Gear Core Zip-T
Test Series by Raymond Estrella
February 17, 2009



NAME: Raymond Estrella
EMAIL: rayestrellaAThotmailDOTcom
AGE: 48
LOCATION: Orange County, California, USA
HEIGHT: 6' 3" (1.91 m)
WEIGHT: 200 lb (90.70 kg)

I have been backpacking for over 30 years, all over California, and in many of the western states and Minnesota. I hike year-round, and average 500+ miles (800+ km) per year. I have made a move to lightweight gear, and smaller volume packs. I start early and hike hard so as to enjoy the afternoons exploring. I usually take a freestanding tent and enjoy hot meals at night. If not hiking solo I am usually with my wife Jenn or brother-in-law Dave.


The Product

Manufacturer: Sitka Inc
Web site:
Product: Core Zip-T
Size: Large (also available in M, XL, XXL and XXXL)
Year manufactured: 2008
Weight listed (Medium): 12 oz (340 g)
Actual weight: 11.9 oz (337 g)
Color reviewed: Stone, also available in Mothwing Mountain Mimicry (a type of camo pattern)

Sitka Gear Core-T Zip

Product Description

The Sitka Gear Core Zip-T (hereafter called the Core Zip or the shirt) is a long sleeve mid-weight shirt positioned as a base layer by the manufacturer, and part of their Core series of base layers. It is made of Polartec Power Dry with Odor Resistant Technology, which according to the tag inside of the shirt is 100% polyester.

The Power Dry with Odor Resistant Technology fabric has a couple things going for it (on paper at least, come back for the Field Report to see if it pencils out). For one it is made to wick, or transfer moisture faster than other fabrics by "using a bi-component knit construction that uses different yarns on either side of the fabric. This creates two different surfaces: one that is optimized to move moisture away from the skin, the other to dry quickly." With the terrain I cover and the pace I maintain I tend to sweat quite a bit, so this is of great interest.Inside fabric

The inside is made of a very tightly woven layer seen above and to the right. The outside has an open mesh type weave to it as seen below. The little pockets create dead air space that when under an outer layer should translate to more warmth.

But the aspect that interested me the most is the "Odor Resistant Technology" part. In this version of their fabric Polartec uses, "pure silver, micro-encapsulated in the yarns that are knit into the fabric construction. It will last for the life of the garment, is safe, natural, and offers permanent odor protection."Outer fabric

I have used silver technology fabrics in other hiking gear, some with very good results. Others, not so good. I will be focusing on this aspect during testing.

The Power Dry material boasts 4-way stretch for good range of motion and feels

A YKK flat nylon zipper runs from sternum level (on me) to the top of the 2.5 in (6.3 cm) high mock-turtleneck collar. The zipper is there to provide extra ventilation, another design feature I really like. They do not have a tag at the back of the collar, but have the name, logo size and place of manufacture (China) screen printed on instead.

There is a tag with washing instructions sewn on to one of the side seams inside the shirt. The instructions are as follows. Machine wash warm. Do not bleach. Tumble dry low. Do not iron. Do not dry-clean. Do not use softener. Wash separately.

The shoulder seams are Raglan-style. This is the way sleeves are sewn on concert jerseys. This style keeps the shoulder seam from sitting directly under my backpack's shoulder strap. This is good in my book. On the bottom of the left sleeve the Sitka Gear logo has been screen printed on.

On the left bicep area a 3 x 5.5 in (7.6 x 14 cm) pocket has been welded (glued) on. It has a vertical flat nylon zipper that has been welded also to eliminate any extra seams. The pocket is made from some 4-way stretch material. It has the Sitka name and logo heavily embroidered on the lower area of the pocket.

On the sides of the Core Zip are 6.5 in (8.9 cm) wide gusset panels running from the bottom of the shirt and culminating under the armpit area. It allows for more range of motion without causing the shirt to lift up, or pull at the side

All of the seams are flatlock sewn. I have found this to be a very comfortable and strong type of seam on other base layers and will be watching to see if it is borne out in the Sitka Gear shirt as well.


Field Conditions

The Core Zip has been worn, or along, on the following trips.

Dave and I went up to the peak of San Gorgonio via the Dollar lake trail as Dave has never been that way. It had rained the day before and they were calling for below-freezing temps so we figured we may see snow or ice. It was 35 F (1.7 C) when we started at an altitude of 6880 ft (2097 m). At the summit it was 31 F (-0.6 C) and the wind chill was registering at 17 F (-8 C). We went 23.2 miles (37 km). The picture below is at the start of this trip.

Jenn and I went to the Ortega Candy Store trailhead and did the Bear Canyon/Bear Ridge loop in the San Mateo Wilderness. 6.8 miles (11 km) in temps to about 80 F (27 C) on up and down trails that were either sandy or rocky. We had 1100 ft (335 m) of elevation gain and loss. (The Core Zip went in the pack almost immediately as it was warmer than expected.)

Dave and I went 27 miles (43 km) on the PCT from Green Valley to Vasquez Rocks This hike saw 5000 ft (1524 m) of gain as we went over three passes in temperatures started at 43 F and climbed to 70 F (6 to 21 C). The terrain was dirt, scree or rock.

Dave and I spent two days in the Tehachapi Mountains just south of Sequoia National Forest. The temps were between 35 and 66 F (2 to 19 C). We went 42 miles (68 km). We had to carry all our water so my pack weight was 35 lb (15.9 kg) starting out.

Jenn and I celebrated New Years Eve by spending the night in Round Valley in Mount San Jacinto State Park. We snow shoed 6 miles (10 km) and stayed at an elevation of 9100 ft (2775 m) on 5 ft (1.5 m) of snow pack. The temps ran from 40 to 22 F (4 to -6 C). Thankfully there was no wind to speak of.

The Core Zip has seen a lot use in Minnesota where I have worn it under a rain coat and down sweater in rain, freezing rain, winter mix and snow. With lots and lots of wind! Temperatures were as low as -12 F (-24 C) with wind chills to -40.

I also wore it skiing in our California mountains.

At the trailhead


So far I have been impressed with the Core Zip as a hiking and backpacking base layer. I have worn it as a solo shirt a few times on hikes and it is comfortable if a little loose. At the last minute I changed my size to an XLarge as I heard the Large did not fit another shorter tester. I wish that I had stuck with the Large as the Core Zip hangs off my arms and body creating folds and bunching when I put a fleece or down sweater over it. My suggestion is to trust Sitka Gear's sizing chart.

The fabric has proven to be quite warm when used under a coat. On the trip to San Gorgonio we hit some high winds and the temps dropped. I just put a shell over the Core Zip and completed the climb without resorting to extra layers which I did have in my pack. (It should be noted that I am a very warm-blooded hiker.)

On the other hand that same wind, any wind for that matter, went right through the fabric. It has the least wind blocking ability of any shirt I own, even my lighter weight base layers. It is almost like the open weave channels wind right through. I am not knocking the shirt for this as it is a layering piece made to be covered, but I hike a lot in just my base layers and have to cover up much sooner with this one.

The odor control has been very good. As good at this point in the test as any synthetic I have used. I will watch this more as I get into some bigger trips now that the holiday season is past. On the New Year's Eve trip I wore it for two straight days. During the night I noticed that where my arm touched my body I was sweating due to having a bit too warm of bag. So I put the Core Zip on to keep the sweat from transferring to my bag and its 800 fill down. After coming home and letting it sit for a couple hours it did not have retained odor. (I on the other hand did have some retained odor until Jenn chased me into the shower…)

The durability has been fine so far. No pulls or loose threads have shown up. As I keep it exposed much of the time it has been subjected to scrapes against rocks and trees but has weathered them all just fine.

One thing I would get rid of is the pocket on the arm. I can't stand the feeling of anything in it, and even the zipper pull bothers me at times. My dad saw it and thinks it would be a good place to keep a fishing or hunting license. I tried a folded up permit and did not care for the feeling. Just call me Mr. Sensitive…



Field Conditions

I wore it on an overnight to San Jacinto State Park chasing storms, they got stuck on the other side of the mountain though. I stayed in Round Valley with a side trip to Tamarack. The temperature got down to 20 F (-7 C) and there was a lot of wind.

A week later I succeeded in finding a storm in San Jacinto State Park. This time I stayed in Tamarack at 9120 ft (2775 m) elevation where it dumped snow on me as I set up my tent, stopping 10 minutes after I got everything inside. It started back up again at 11:00 PM. I was on five to six ft (2 m) of snow when I made camp. The temperature was 22 F when I stopped, 19 F when I made dinner and 17 F at 9:30 PM, the last time I looked at it. (-6, -7, & -8 C) There was a lot of wind in the early morning hours. I hiked 7 mi (11 km), all on snowshoes.

Next I wore it on a backpacking trip with Jenn to San Mateo Wilderness in Cleveland National Forest. We did a 9 mile (14.5 km) first day with an all up-hill 3.5 mile (5.6 km) hike back the next day. It hit 75 F (24 C) for a high but felt hotter in the sun, and got down to a chilly 28 F (-2 C) at night. High elevation was 2000 ft (610 m) with a total of 1300 ft (400 m) of elevation gain and loss.

Lastly I wore it on a 15 mi (24 km) winter peak-bagging trip to the Mt Baldy area. We summited Timber Mountain, Telegraph Peak and an unnamed peak in one day. Conditions ranged from dirt trails with some snow on the approach to ice fields, hard frozen ground and rock. I did not carry a thermometer but will guess the temps to be from 30 F to 60 F (-1 to 16 C). That is where this picture was taken.

On frozen snow


The Core Zip-T has continued to work very well as a stand-alone hiking shirt and a base layer.

It is in very good shape even though it has been washed more than is apparent by the trips used on. This is because I have worn it in Minnesota on my one-week-a-month trips where we have had a very cold winter. It is still in perfect shape with no stretching, shrinking or drooping observed. All the seams are in good shape including the ones where my pack hits.

Speaking of which I have not seen any pilling of the fabric due to wear from the pack that I see on so many of my shirts. It is proving to be quite durable.

The odor control has been very good. Often I wore it for two days straight, even sleeping in it. While it can't help but be smelly while my stinking bod is in it, the Core Zip did not retain odor. I have shied away from using synthetics because of shirts I had that still smelled after being washed even. No problems with this shirt though.

I really like the long zipper it has. It is nice to open it all the way to help cool me off after climbing hard. I do have to remember to zip it partially back up when I run into people as I have got some funny looks from my dipping front. The zipper has run smoothly the entire time and has never snagged.

Once in camp, and no longer in motion, I will start getting cold. A quick tug sends the zipper and mock turtle neck up to keep me warm.

While the pocket on the sleeve did not bother me (if left empty) I would just as soon see them forgo it. I have pockets enough as it is on my pants, coat and pack to need one on my shirt too.

I would like to commend Sitka Gear on the ability of this hunting shirt to also be used for backpacking duty. And I will thank them and for allowing me to prove it so.

This report was created with the Report Writer Version 1. Copyright 2009. All rights reserved.

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