Synthetic puffy/belay jacket system

At a long 10 degree belay, I might find myself cold in the combo you mentioned. Couldn't hurt to test it while ice cragging though. I used a similar system for CO ice climbing last winter except with a rab xenon and a rab infinity jacket layered over. It kept me plenty warm. I'm too curious about water resistant down not to give it a try, so I'm waiting on a brooks range mojave in the mail. If the downtek works close to as well as a synthetic, then I'll have a one piece 16 oz belay system, and the infinity will be on gear swap.

That said, its nice having a light synthetic puffy, b/c then I can go with a lighter, more air permeable action suit, and throw on the light puffy for moving when its really cold. Moving in a light synth is also a good way to dry off base layers quickly because your pushing the moisture through faster than just standing at a belay. Something like an arcteryx atom LT, would be a good compliment under your rab generator alpine b/c its decently warm under another shell (from what I hear) but it breathes well and dries quickly. I'd also highly recommend the rab xenon if you can find a good sale. It feels noticably warmer than other light synthetics I've tried including the thermawrap parka. But there I go suggesting more stuff for you to buy. Might as well test out the thermawrap generator combo first though.

Just some ideas. Sorry, I'm not clo smart.

My first thought was about what you are wearing for mid layers with something like an R1 or Power Stretch hoodie under the belay jacket. The next thought was layering a vest, like the REI Revelcloud or Patagonia Micro Puff.

The fleecy mid-layers won't compress and will have a thousand uses in the Scottish climate. A vest will deliver good core warmth and good warmth/weight. The vest can be alternated with a full jacket and used for primary insulation on summer trips as well.

Dale is correct. Fleece is a mainstay of Scottish winter climbing.
You may also want to look into Buffalo clothing, as that was basically developed around the sweat/chill conditions of winter climbing in Scotland.

You could always stick a lightweight down hoody under the Generator Alpine.

I am thinking of trying this out with a Dead Bird Atom Sv and Gooses feel down hoody I have.

Dane Burns, a well-known ice climber, likes: “the Arcteryx Atom Lt Hoody, a lightly insulated shell with stretch-fleece vented sides and under the arms. Again a surprise, water resistant as well but not waterproof. Very warm for its weight and thickness but useful in the right temps (cold) for hard climbing because the stretch side panels and insulated body breath so well.”

What I wear under the belay jacket system will vary depending on climbing conditions for the day, and will be tailored for breathability during high output activity. Normally I will have some combo of two of three of the following: a 150 merino t-shirt, R1 type hoody, marmot dri-climb, and Shoeller Dryskin jacket. I have my climbing layers pretty dialed.

I do like the idea of using my Generator Alpine if I'm moving slowly when it's very cold, and I got mine fit well enough to climb in. That also means it won't fit a thick insulation layer underneath, unless its a very thin layer like the Thermawrap UL, which I'm believing won't be enough for a real belay jacket system. I'm a little bit leery of vests since I'd like a little more insulation on the arms, though I know arms are less important than torso.

After tons of research and number crunching, the non alpine Rab Generator looks like it might be the warmest for its weight that I can find. Ideally I'd like to find a 13oz ish primaloft one jacket with at least 100g fill in the torso. Bonus points if it has a hood and can unzip from the bottom. Anything I'm not finding that matches that? Again, the reason I'm not into down is that I can't stuff it into a pack full of ice screws and crampons. I'm also not worried about staying dry during output or any of that, I have it covered. I just need to stay warm while stationary. A quick on-off piece for long belays.

i think you nailed it with the generator pull-on or jacket.

First ascent igniter jacket? Not sure if it zips from bottom.

The generators are good kit, I have the vest but thinking of getting a pullover.

In addition to the Generator I've also been looking at the La Sportiva Pegasus and the Brooks Range Cirro and Cirro Extreme.
The Pegasus is perfect other than no bottom zip. The Cirro does have a bottom zip but doesn't quite have enough insulation, and the Cirro Extreme, though a little heavier than I want, does have a better amount of insulation (120g PL1) and would make a better overall system – if it had a bottom zip.

100g Primaloft One and 13oz is tough to find. The Arc'Teryx Atom SV is around 16oz, Patagonia Micropuff is similar. Both those are pretty light compared to some others, and I'd want more protection than either of those jackets in the winter.

My SV is 19oz in XL.

Dane Burns should generally be trusted on his insulation assessments since he has and still spends so much time in sub-freezing conditions.

Based on his latest review of synthetics the Montbell garments should be considered. Regarding exceloft he says:

MontBell is using their own Exceloft synthetic insulation. “Exceloft a combination of 8-denier compacted polyester tubing with extra-thin, 0.7-denier polyester thread makes the insulation remarkably compressible. In addition, Exceloft absorbs very little water, making it highly resistant to saturation and extremely quick to dry.”

Montbell Thermawrap Pro Hoody: This is a jacket that made me realise I really am a gear snob. For it’s 80g weight it seems warmer to me than the Atom SV @ 100g by comparison. I really like the pattern and detailing of the Pro Hoody. The hood (which will take my helmets) and slick knit cuffs stand out. No adjusting required on the cuffs. As does the pattern’s cut. The Pro is an athletic cut and very fitted. This has become one of my very favorite 100g jackets…even though it is only 80g weight insulation. Go figure! Big surprise to me all round and a very pleasant surprise at that.

Doesn’t get anyone under 16oz for 100g/m2 insulation but should be a bit less bulky.

do we know the clo values for exceloft … someone once posted them up and they werent favorable at all …

hmmmmm

Size L for $79. Can't get any better value that this :)

The according to RN in the paradigm thread, the iclo for an 80g/m2 Thermawrap Parka is 0.77 and the iclo for my Rab Generator Alpine is 2.27. I've never worn the Thermawrap, so I can't comment on that, but its hard to believe that it would be only a third as warm as the RAB. In another thread that I can't find now, I saw him mention that he was thinking that exceloft was very close if not equal to PL1 as far as clo/oz. I'm confused about it all, but either way, I'm sticking with PL1.