I am sitting at my desk with a ton of information at hand. But nothing on the Arcteryx ThermaTek or Coreloft that I can verify. I asked Arcteryx directly twice but didn't get an answer. I want to make an informed decision on a jacket purchase and this isn't making it easy. When the jacket is $699 retail one might pause before "jumping in".
"Fisson SL (76g) and a Duelly (152g) of ThermaTek "
The question I want answered is: How does the
Arcteryx Fission SL, shell is 2 layer Gortex, 76g g/m fill, weight 27.6oz and $699 retail
compare with some thing like a
RAB Alpine Generator Hoody, shell is Pertex® Endurance, 100g/m fill, weight 20.7oz and $235 retail
Or very close to the same if not equal warmth....below, the Arcteryx Atom SV Hoody, 100g/m Coreloft, weight 18.6oz and $259.00
I find the difference in retail pricing troubling and the extra weight even more so. Having both jackets here at hand makes a physical comparison easy enough. I might believe the Gortex Fission will be the equal to the Generator for warmth. But the Generator and the SV both show more insulation thickness. The Rab version has more insulation and it's insulation is 5% better than Coreloft according to the Arcteryx source. Where does the high tech Polarguard Delta (aka ThermaTec) fit into that equation? Because 76g/m sure doesn't look very warm compared to 100g/m sitting here at my desk! ThermaTec had better be some amazing stuff. And if it is such amazing stuff as the price would indicate how come there is no comparitive numbers to show us?
What am I missing? Because it looks to me like any one of the 100g/m jackets will be warmer (although not water proof like a Goretex garment) and a LOT cheaper. Enough so you could easily still buy a Gortext or Neoshell and still be ahead with only a 8oz penalty on the Fissoion SL (Super Light?).
I'd really like to keep the Fission SL. It is a nice jacket. Just wondering how that price point is some how justified. Anyone have an answer they care to share?
This is a letter from Arcteryx to a customer I have seen:
"Currently, Arc'teryx does not have a recorded clo value for Coreloft. Apparently, there are two standards for testing clo value when it comes to Coreloft and even these tests vary with weight. In some instances Coreloft was tested and found to have a higher clo value compared to Primaloft. Other instances, Coreloft was tested with a lower value compared to Primaloft. Overall, I was told
that the accepted standard is Coreloft falling 5% below Primaloft One when tested head to head.
With regards to Synthetic fiber fill there's two factors that relate to warmth.
One is clo and the other is loft.
Insulations with high clo values, like down, are very fast acting. A garment with a high clo value, once on, traps your body heat very quickly. In comparison, insulations with high loft, generally have a lower clo for a given weight. The higher loft takes longer to heat the insulation and feel the insulation warm, but there is the potential to trap a lot of heat. Down being the ultimate combination of both clo and loft.
Frequently, to make up for Primaloft having a higher clo, Coreloft has a little more loft.
I was also informed that when determining the warmth of down, knowledge of the weight is really important because the density of the down can vary. However, synthetic insulation is different because the density does not vary. When comparing 2 comparable synthetic down jackets, the higher the g/m^2 the warmer it will be."
More to the point I think depending on what is true and what is merely speculation on the author's part:
"This one is warmer and also will be way better at resisting any moisture pickup due to the totally waterproof Thermatek fill. Another consideration is the construction; the insulation is laminated to the inner shell so there are no cold spots from baffle stitching, and this also makes it's loft last longer.
Thermatek is the Bird's trademark name for taking Polarguard Delta insulation, and then dipping it in DWR, and then LAMINATING it to the face fabric. It's spendy because it's just as labor intensive as it sounds, and no one else does anything like it.
The ThermaTek uses a bit different construction so this will be equivalent warmth to the Atom SV.
Therma-Tek and Primaloft-2.7 (78gm) Thermatek and 133gm Primaloft offer the same loft"
This is a good read:
RYAN JORDAN is the Founder/CEO of Backpacking Light
Polarguard is the most popular insulation for synthetic sleeping bags. It is an extremely long strand fiber, and it is possible that the insulation in a sleeping bag might consist of one continuous strand. This fact helps the insulation last longer, as the long strands are less likely to clump. Because it is comparably stiff, you don’t see Polarguard in applications other than sleeping bags very often. There are four generations of Polarguard out there, and you still see all of them floating around. In order of ascending performance and cost, they are: Polarguard, Polarguard 3D, Polarguard HV, and Polarguard Delta. Delta is the pinnacle of the Polarguard line, and consists of hollow fibers for the lightest weight and highest efficiency. You will see this fill in most higher-end synthetic sleeping bags.
Primaloft has occupied the opposite end of the construction spectrum from Polarguard, with soft short-strand fibers made from microfiber polyester. Primaloft is highly compressible, very soft, and feels a lot more down-like than any other synthetic insulation. It also has remarkable water-resistance properties. The principle drawbacks to Primaloft are durability and price. Because of its short fibers, Primaloft is more prone to bunching and sees limited use in sleeping bags. While it is still cheaper than down, it is at the top of the price range for synthetics. There are a few varieties of Primaloft, but the most commonly seen are Primaloft Sport, the value option, and the higher-end Primaloft One, which features finer fibers and more water resistance. The newest material from Primaloft is called Infinity, and it is Primaloft’s entry into the continuous filament field. Look for it to compete against Polarguard Delta in sleeping bags.