Long Term Report - Zyflex Thermals

20-September-2006
Roger Caffin

Reviewer Details

Reviewer:	Roger Caffin
Age:	60
Gender:	M
Weight:	63 kg (139 lb)
Height:	167 cm (66")
Email address:	r dot [surname] at acm dot org
Home:	Sydney, Australia

Backpacking Background

I started bushwalking at 14 and took up rock climbing at University with the girl who became my wife and my permanent walking partner. Ski touring and canyoning followed. Winter and summer, we prefer long hard trips by ourselves: about a week in Australia, up to two months in Europe/UK. We prefer fast and light in unfrequented trackless country. We would be out walking and skiing for at least three months a year. We have now moved to lightweight gear, much to our backs' relief. I designed and made much of our lightweight gear myself.

I am also the maintainer of the Australian aus.bushwalking FAQ web site www.bushwalking.org.au/FAQ/.

Product Information

Manufacturer:	Zyflex	www.Zyflex.com/
Year of manufacture:	assumed 2006
Country of manufacture:	Romania, using American fabric
Size:	Medium
Material:	59% Polyethylene, 35% Nylon, 6% Lycra
Care:	Cold wash, do not tumble dry
Colour:	Grey (I think)
Model:	Thermal Shirt	Thermal Pants
Listed weight:	7 oz (198 g)	6.6 oz (187 g)
Actual weight:	8.0 oz (228 g)	6.2 oz (175 g)
MSRP:	US$34.99 *	US$29.99 *

* I listed the MSRP as US$19 for each item in my Initial Report and Field Report. Those prices were obtained from the Zyflex web site shortly before the Initial Report was posted. I note the web pages for the Shirt and Pants have since changed, and these new prices posted. They represent some serious inflation.

Product Claims

More complete details about the product are given in my Initial Report. Briefly, these are thermal underwear, but the fabric is a bit different from my previous experiences of thermal underwear. The effect of the inclusion of some elastic Spandex in with the microfibres is very noticeable.

Going by the manufacturer's sizing chart I seemed to be at the borderline between Small and Medium, and I noted this in my application to test. Zyflex rather generously supplied me with both Medium and Small versions, and I have mainly been wearing the Medium version. The Medium Pants seemed tight at the start but the Medium Shirt seemed very loose. I tried the Small Shirt, but it was too small in other ways.

Relevant Personal Background

I have spent 27 years as a research scientist working in the field of Textile Physics. This has given me some experience with fabric construction and fabric physics. In addition, I have been making walking gear and walking clothing for the last 20+ years, and have considerable practical experience in design and sewing. I mention this here as I am making several critical judgments below.

Field Impressions

I am going to repeat some of my comments from my Field Report here because they remain very relevant. The clothing has been worn at home, under various clothing, and once at night time inside my sleeping bag in the field in the Blue Mountains during winter.

The 'feel' of the fabric itself is strange. It contains Spandex, which is elastic, and this seems to give it a feeling which is part rubbery and part light canvas. It rustles like light canvas as well. I suspect the weave is tighter than it should be for a couple of reasons, detailed below.

After wearing the Medium Pants for a day I noticed marks from the seam down my skin, above and below my knees. This suggested that the legs were rather tight, and I became concerned as to whether they were too tight and might restrict the blood flow a bit. This was confirmed when I wore them one night in my sleeping bag on Cronje Mountains (942 m or 3090'). It got down to 4 C (39 F) overnight - not extremely cold. I found I had cold legs, but was able to restore warmth to them by removing the Pants. Since then I have not been willing to use the Pants in the field.

Equally, I found the looseness of the Shirt was a problem in my sleeping bag as it let drafts in. This was not acceptable for field use either.

Home Use

With all the above problems one might wonder whether I have been able to find any use for the Zyflex thermals during the Long Term Report period. In fact, I have worn them quite often - at home, working around our farm, in our winter. Normally I would have some cotton or poly-cotton overalls over them while doing this. Temperatures at home have got down to freezing, but wind has been minor.

The Pants are still tight of course, but when I am working I am moving, and the movement of my muscles seems to allow the blood to circulate around my legs. So my legs have been warmer with the Pants on than without - or so it has seemed to me. The looseness of the Shirt has not been so much of a problem either, for two reasons I think. The first is that the overalls have kept the Shirt pressed against my chest, so drafts have had less chance of creeping in. But the second and just as significant reason is that when I am working I am simply not that sensitive to a few little drafts at my chest. The overalls have stopped any looseness around my waist where I might feel the drafts a bit more. In addition, the toughness of the fabric (and it is tough) has been useful: I never worry about damage.

However, I did notice that the knees slowly got a little baggy as a result of lots of kneeling. The amount is minor, and not unexpected. I also noticed that kneeling in mud did leave a bit of a stain on the fabric which survived washing. But it was not very significant either.

Maintenance

The top and pants have been washed a number of times, and have shown no sign of any change in size from the washing. They show relatively little sign of surface wear. The fabric seems very robust. The cuffs on the arms and legs don't seem to have changed from being worn or being washed either. Drying remains very slow however, as I reported in my Field Report.

I repaired the unraveled seams mentioned in my Field Report. The repair is fine, and no further problems have appeared. I believe this was simply a manufacturing fault rather than 'wear'.

Summary

These Zyflex Thermals are very strange things. I do not think they are suitable for use walking, at least not for me. However, they have proved quite useful for rougher wear around home and the farm.

Individual points I have been monitoring have not changed much:

Fit and warmth and comfort over all?
Unsatisfactory: the legs are dangerously tight and the top is loose and drafty.
Leg tightness: does this restrict blood flow and cool my legs?
On me, yes, definitely. This is dangerous.
Body looseness: does this let drafts in and reduce the warmth?
On me, yes. This negates the whole point of 'thermals'.
Sleeping use - could they be used in cold weather with a lighter bag?
Definitely not from my experience.
Shoulders - how much does the top 'ride up' with my arms up?
It doesn't with the Medium size. The Small size is too small for me and does ride up.
Neck - what size hole is it, and is it drafty?
Yes, it is a little large and a noticeably drafty.
Arm length - how much arm waving can I do and keep the cuffs at my wrists?
This is not a problem.
Cuffs - do they stretch out and become floppy over time?
No, they are robust.

Stretch - how much and how well does the Spandex knit fabric work?
I find the elasticity a bit too strong. There has been a slight bit of permanent stretch around the knees.
Drying - how fast do any damp patches dry out in the field?
They dry very slowly and radiant heat had to be used.
Softness - do they make a good pillow when rolled up?
This has not been tested.
Fabric durability - just how abrasion resistant is the fabric?
It seems quite robust, even under use around the farm.
Fabric wear - under shoulder straps and down the back.
They have not had a lot of use in the field, but no wear has been seen.
Seams - how well are they sewn and finished, do they last?
I find the lumpy seams unsatisfactory: they leave marks on my legs. The stitching had defects in a few places.
Pilling - does the fabric suffer from this?
There has been no sign of this at all.

Read more reviews of Zyflex gear
Read more gear reviews by Roger Caffin

Long Term Report