Reviews > Clothing > Underwear > Hot Chillys GeoThermal Tops and Bottoms > Roger Caffin > Field Report

Field Report - Hot Chillys Geo Thermals
Roger Caffin

Product Information

Preamble

The start of this test was not all that auspicious. I had requested a crew neck top but received a zip neck top, and I was not able to get any response from Hot Chillys about this before writing the Initial Report. The clothing was far looser than all my other 'thermal' clothing, and therefore did not seem to fit. I thought I had problems.

It turned out that the zip top had been supplied by a marketing/PR firm working for Hot Chillys because they didn't have any crew neck tops at the time. They were aiming at speed of delivery: they hadn't realised that at BackpackGearTest we really test the gear supplied. Once I got into communication with them the problem was quickly resolved and they shipped a crew neck top as soon as one was available. (The IR was subsequently revised to reflect this.)

My concern over the loose fit was really an error in my expectations. I had not read the description on the web site closely enough: Hot Chillys state that the garments have a 'Relaxed fit' and a 'Lived-in feel for active or casual use'. I had been expecting a snug body-fit with a moderately winter-weight like all my other 'thermals' bought in Australia. It would seem that ordering stuff (especially clothing) over the web may not be a simple as some would have us believe! Touchy-feely still has something going for it.

Field Testing

Testing has been done in two parts: at home and on trips. So far I can report as follows.

Bio-Silver®

Frankly, I had expected the claims about the Bio-Silver to be just marketing gumph so I tried wearing the tops around the house for a week at a time before washing them. This seems to be the 'standard' BGT test period for such things (smile). Somewhat to my surprise, and very much to my wife's surprise, the normal pong one would expect to get after a few days did not really seem to materialise. OK, by the last day of the week my wife did say it was time I handed them over, but it still was not 'bad'. This was not a one-off event: I repeated the test several times. So it would seem that the silver treatment really does have some effect. However, I must add that after about 4 - 5 days of continuous wear I was conscious that some sweat had built up on the fabric. I could 'feel' it as a sort of irritation. So while the Bio-Silver treatment might suppress my smell, it does not remove the need for daily washing of my clothing. No miracles!

Questions I cannot answer yet are just how many wearings and washings this effect will survive, and what effect if any the Bio-Silver will have on my skin. All I can say so far, after two months of intermittent use, is that the Bio-silver still seems to be inhibiting the bugs but not worrying my skin. The Long Term Report will doubtless provide more information on that.

Tops: Zip neck vs Crew neck

I tried wearing the zip neck top even though I was doubtful about it. Since the tops are advertised as a 'base layer' I wore nothing under the top, between the zip and my skin. Sadly, I have to report that the fabric of the zip irritated my skin, causing a bit of a red rash, and the zip seemed to get caught up in the hairs on my chest. (The latter would not concern ladies of course.) Out of curiosity I compared the zip arrangement on this top with other garments I have which have zips at the necks. All the others had some sort of protection over the zip which kept it from contacting the skin. I dare say this problem would not occur if the top was worn over something else (see under 'Warmth'), but it was advertised as a base layer. On the other hand, the crew neck top was very comfortable at the neck, and did not irritate my skin at all.

There are actually two differences between the tops, although the web site only shows one of these differences. The neck of the crew neck top is plain like a conventional crew neck T-shirt, while the zip neck top has a 50 mm (2") high band collar. This is shown. There is a similar difference at the wrists: the crew neck top has very narrow simple hems, while the zip neck top has the more conventional tightish band cuff. The web site shows only the plain wrist design, but this is not a big issue. These style differences are consistent with my impression that the crew neck top is suitable for casual use or underwear while the zip neck top is more suitable for outerwear.

Trousers

The tops are of course much more presentable as a casual item of clothing than the trousers: the elastic waist with the Hot Chillys logo woven in and the fly make them look a little too much like underwear to be worn in public by themselves. In addition, the trousers (quite sensibly) don't have any pockets. They also have the simple hem at the cuffs mentioned above. As mentioned above, I did try wearing the trousers around the house in cool weather with the two tops on together: the crew neck underneath and tucked in, and the zip neck on the outside over the trousers waist band. This worked and covered both the waist band and the fly, although there was a very significant difference in warmth between the single and double layers. However, my wife was not convinced that the result was all that more suitable for public viewing.

The bottoms could of course be worn under other trousers in very cold weather: right now (summer time) we don't have much of that here in Australia. In practice I only wear a second layer under trousers in very cold weather, and then I usually need something a bit warmer than these. However, I don't think Hot Chillys meant these garments for winter use.

Warmth

I feel these garments fit somewhere in between a loose cotton T-shirt and the snug thermals of the type I take walking in winter, and that is pretty much how Hot Chillys describe them on their web site. I have found them quite comfortable when worn by themselves around the house in fine or warm weather (say 25 C or 77 F). However, I found that the loose fit meant that there was very little trapping of air for insulation inside the garments when I wore them as an outer layer, so they were not really functioning as 'thermals' in my use of the term.

When it got a bit cooler (around 20 C or 68 F) I tried putting the zip neck top over the crew neck top. This meant the crew neck top underneath was now able to trap air and provide some insulation. This was better: the combined tops were as warm as a good Australian thermal top and the zip was of course blocked from my skin. However, as a weight-conscious walker I have to note that each top weighed as much as one of my other thermals: there's a weight penalty here. I dare say any other not-very-loose top might have substituted for the zip top in this test, but other tops don't have that cute little Hot Chilly zip pull! However, as might be expected, there was now a significant difference in warmth between the double-layer top and the single layer bottom. My legs were just a little cool. I would have needed to put on light trousers to balance the effects, and this would of course have been very similar to conventional lined track suit pants. I did not bother as I was not that cold.

At slightly lower temperatures, getting down towards 17 C (63 F) I found the single layer on my legs was just not warm enough, and I had to either put some light single-layer synthetic track pants over the Hot Chillys bottoms or change into ordinary lined synthetic track pants (of the cheap sports-store variety). The double layer on top was adequate once I warmed up my legs, but not what I would call 'warm'. Clearly I had reached my limit with these garments.

Overall, I found that wearing one of these garments as an outer layer gave me at most a 3 C (5.4 F) boost in temperature, while wearing the crew top as a base layer under something else gave me about a 4 - 5 C (7 - 9 F) boost. The difference would of course be due to the loose fit. Based on these figures I would question the use of the term 'thermals' for these garments. I (and my friends) have always used this term in the shell/layering concept of outdoors clothing to mean a base layer which has a snug or body-hugging fit and is warm at quite low temperatures - well below 17 C (63 F). I would argue that there is some industry consensus around this use of the term, even if there is no formal definition of the word in measurable terms. My wife and I often wear just a layer of our other thermals in the tent in the evening, down to about 10 C (50 F). Ski-touring in sub-zero weather we would have a thermal layer on underneath a light outer layer.

Warmth per Weight

I found that these garments weighed about the same as my other warmer thermals while not being nearly as warm. Clearly, if I had to make a choice which ones I would take on an off-season trip, I would be taking the warmer ones. My problem here was that I had initially expected these garments to match my other thermals, on the basis of the use of the name 'Geo Thermals'. I was wrong.

Fleecy insides - comfort

This is one of the more important aspects of any base layer clothing: how it feels against my skin. In assessing this it has to be remembered that these garments are a loose fit rather than a snug fit. In fact, I am not really all that conscious of the fabric against my skin. It has a soft feel, but most certainly not an intrusive feel. I would ascribe this to a combination of the loose fit and the lightly fleecy inside layer. So the claim of a 'lived-in feel' seems to be 'just about right'. They are quite comfortable.

Allied to this I note that Hot Chillys mention a flat seam design. The seams down the arms and sides seem to have been done with a rather sophisticated 4-needle overlocker sewing machine. They are quite flat on the inside and unobtrusive. There was no scratching or irritation from them. This was quite good.

Fit

This is a very tricky thing to assess and describe. I weigh 60 kg (9 st 6 lb) and the garments are a relatively loose fit on me, but are the right length. Are they that loose because I am fairly light? Probably.

Well, the crew neck fitted easily over my head, as did the zip neck version. The sleeves are slack over my arms and come down to my wrists when my arms hang down. That's not very long, but quite suited to casual wear. I described the cuffs and neck above: they too are comfortable. The waist part of the top comes down over most of my backside and has some slack around my middle. The waistband on the trousers fits slim me just fine, although it might be a bit tight if I was a lot heavier! The legs are like the sleeves: they come down to my ankles and are a relatively loose fit around my legs. The ankle cuffs are like the wrist cuffs - narrow hems and not tight either. They do not get in the way of any footwear.

Moving around - walking etc, means the fabric rubs across my skin, especially at knees and elbows. It does not drag on my skin, and that is good. When I sit down the ankle cuffs ride up a little, about 50 mm (2") above my ankle bones. This is fine in reasonable weather. I am just not very conscious of the garments when wearing I'm them, which fits right in with the Hot Chillys description.

Wear

There has been some mild wear on the surface but very little deformation. The visible wear is a small amount of pilling on the knobbles of the fabric over a couple of areas. I am not sure whether I rubbed up against something to cause this, or whether it just happens in ordinary everyday use. But it is visible, especially when viewed at an angle. Photographing it so this is visible will be tricky so I haven't tried to do this yet. I will be monitoring this closely to see if it gets much worse during the rest of this trail. I should add that some 'high quality' outdoors garments we have bought recently have pilled far worse than these tops, and some skivvies I bought have stretched horribly after a few wearings or washings, ending up wide and short - but they were cheaper ones. All in all, The Hot Chillys fabric seems fairly good, but long term testing will shed more light on its life.

Field Use

I have tried these out in the evenings in the field, but only in fine weather. In our Australian bush I wear moderately heavy full-length taslan nylon clothing during the day: a windshirt and trousers. These are needed for our scrub, but they do sometimes get a bit sweaty by the end of the day. These Hot Chillys garments have made a pleasant change from my day-time clothing in the tent in the evening, but did not add much warmth. Unlike our other thermal clothing, these are not warm enough for me in cooler weather without a second layer over them. Unfortunately they bring no weight advantage.

Water repellency

I have noticed that some fleece-wear is mildly water-repellent. Typically what happens is the drops of water stay on the outer surface as beads, and can be shaken off. This is of course very convenient when wearing a fleece jacket in misty weather, or even in very light rain. I tried wearing the Hot Chillys clothing in very light rain and found it was not water-repellent in any way: any drops contacting the surface of the fabric were immediately absorbed and diffused. I subsequently tried putting on the crew neck top after a shower, before I had dried myself. Again, I found the fabric quickly absorbed the drops of water off my skin.

I think this affinity for water is reasonable. After all, I want the inner surface of the fabric to draw off any sweat on my body and dissipate it. This can only happen if the fibres attract water - if they do not have any water-repellent characteristics. I doubt very much I can have it both ways in such a light fabric - that the inner surface should be hydrophilic and the outer surface hydrophobic. In fact, in a sense it was reassuring to find that the fabric did wick water away so fast. I think this is as it should be.

Washing

I am not an expert with washing machines, but the fabric and the garments seem to take being washed in with the rest of my coloured clothing just fine. They came clean and non-smelly, and did not deform. I did remove the cute little Hot Chillys zip pull before washing! In fact, there really is little to report here other than that they were easy to wash and there were no problems. This is a good report of course.

Assessment so far

These are mainly the points I listed in my Initial Report for assessment.

• Warmth - including some comparisons with the range I already have, taking the looseness into account
  Not as warm as my other 'thermals', but not advertised as such. Warm enough for me for summer time evenings or at home. Warmer with a second layer over them too.
• Warmth per weight 'effectiveness' for an ultra-lightweight backpacker
  About the same weight as others, but not as warm as my other locally-sourced 'thermals'.
• Comfort - do they feel 'nice' to wear and do I warm up fast when I put them on
  Quite nice to wear. I don't take them on trips where I might need serious warmth.
• Fit - mainly how easy are they to get on and off
  They fit me as advertised: a 'relaxed fit'. They are easy to put on and don't get tangled coming off. Equally important, they are retaining their shape and size.
• Water affinity - does the fabric repel or attract drops of water
  The fabric does seem to wick away any loose water off my skin quickly. They are not meant to repel water.
• Smell - Hot Chillys claim to have this perennial problem licked - yeah?
  To my surprise, they do seem to have a reduced pong, even after several days wearing.
• Washing - how well do they wash, and do they come clean and smell-free
  No surprises here: all seems to be well. My sweat accumulates as normal, and needs to be washed off as normal.
• Cuffs - a special category in the comfort class
  The simple cuffs are loose, as appropriate for the design. They haven't deformed at all. The band cuffs are also doing well.
• Wear - how well do they last under clothing and in the tent
  They have lasted fairly well so far, but are showing a little pilling. They are rarely worn in the tent.
• Waist region - what does the trouser waist band feel like, and does the edge of the top stay down under it
  The waist band is fine, the bottoms stay up, and the top does stay tucked in. A fat person might feel the waist was a bit tight.
• Neck - is the crew neck comfortable to wear and does it go over my head easily
  The crew neck is just fine.
• Zip - is the zip at the neck comfortable enough
  No, the bare zip has not been satisfactory. It seriously irritated my skin. I could not recommend the zip top for use as a base layer. Worn over another layer it was OK.

Testing for the Long Term Report will assume these garments are not 'thermals' in the outdoors sense but casual or sports clothing. This will allow them to be assessed in their most appropriate context.

Summary so far

• I would certainly consider buying the crew neck top as a conventional skivvy for home use in fine weather (subject to a price check of course).
• The zip top would also be nice as casual wear in fine weather if worn over something else, but definitely not by itself unless the zip arrangement was improved.
• The trousers are well made, but in practice I would not have a lot of use for them either at home (too 'underwear') or in the bush (not warm enough).
• I would not recommend any of these garments for use in cold or even cool weather. Judging from the Hot Chillys web site, I don't think they are really meant for that.
• I have to add that I do not think that these garments match my concept of term 'thermal underwear', or even come close, but that's my personal bias.

Reviewer Details

Reviewer:	Roger Caffin
Age:	59
Gender:	M
Weight:	60 kg (9 st 6 lb)
Height:	168 cm (5' 6")
Email address:	r dot (surname) at acm dot org
City, State, Country:	Sydney, NSW, Australia

Backpacking Background

I started bushwalking (the Australian term) when I was about 14 yrs old, took up rock climbing and remote exploration walking at University with the girl who became my wife, and later on we took up ski touring and canyoning. These days my wife and I do all our trips together, very often by ourselves. Our preferred walking trips in Australia are long ones: up to about a week in the general Blue Mts (east coast of Australia) and Snowy Mts (alpine region), and up to two months long in Europe and the UK. Ski touring trips would also typically last up to a week. We favour fairly hard trips of some length and prefer to travel fast and light. Many of our trips are explorations in wild country which sees few other walkers. Australia does not have 'huts'; we always sleep in a tent. In between these long trips we do some day walks, often exploring the start of longer trips. On average, we would spend at least two days per week walking or ski touring. Over the last few years we have become converted to the concept of ultra-lightweight walking, and have been cutting our combined pack weight down from 36 kg (80 lb) total to about 25 kg (55 lb) for week-long trips. I have also been designing and making ultra-lightweight gear for our own use under the harsh Australian bush conditions.

I am the maintainer of the Australian aus.bushwalking FAQ web site www.bushwalking.org.au/FAQ/ which is hosted by the Confederation of Bushwalking Clubs NSW in Australia. I am also the web master for the Confederation and the editor of their magazine 'The Bushwalker'. In addition I have written gear reviews for 'Wild', a local Australian walking magazine and for BackpackingLight.com in America.

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