Sea to Summit Cinder Quilt Review

The Sea to Summit Cinder Down Quilt is a summer-weight ultralight quilt rated to 50 degrees Fahrenheit that weighs just over a pound. It’s made with water-resistant 750+ fill RDS certified down, has sewn-through baffles, and can open up completely flat into a unique oval shape that is widest in the middle to prevent drafts. The Cinder is specifically designed to attach securely to a sleeping pad with straps underneath it and a footbox that slips over the end of a pad, but it can also be used freely on top of a pad. Additionally, it can be used as an over-quilt to extend the range of your sleeping bag into colder temps and has mating snaps to connect to Sea to Summit’s own sleeping bags and stay in place on top of them.

Specs at a Glance

• Temperature Rating: 50F / 10C
• Weight (manufacturer): 17 ounces / 480 grams
• Weight (measured): 16.9 ounces (quilt alone), plus 1 ounce for four pad straps and 1.6 ounces for the compression stuff sack. (19.5 ounces for quilt, straps and stuff sack).
• Fill Weight: 8.5 ounces / 240 grams
• Fill: 750+ ULTRA-DRY water repellent down, RDS (Responsible Down Standard) certified
• Materials: Shell: 20D NanoShell Nylon, Liner: 20D nylon
• Dimensions:
  • Width (manufacturer): 47.2” / 59” / 34.3” 120 / 150 / 87 cm circumference (chest/hip/foot)
  • Width (measured): 48” / 56.5” / 35” 122 / 143.5 / 89 cm wide, measured flat
  • Length (Regular): 64” with footbox closed, 72” flat (measured)
• Sizing: Regular length fits a user up to 6 feet tall, according to Sea to Summit. A long version (6’4”) is also available.
• Compressed size (in stuff sack): 5.9″ x 13.8″
• Included: Zippered mesh storage cube, compression stuff sack

Sewn-Through Design

The Cinder has sewn-through baffles, as does Sea to Summit’s 40F Ember quilt. Sewn-through baffles are frequently used for warmer weather quilts because the cold spots felt at the stitch lines are less of an issue than they would be at lower temps. Sea to Summit’s 30F and 20F Ember quilts switch to box baffles to eliminate these cold spots.

RDS Certified ULTRA-DRY down

RDS means Responsible Down Standard, and their certification process means that the down was harvested humanely, not from live-plucked or force-fed ducks and geese. ULTRA-DRY down is one of several treatments available in the industry for adding a DWR (durable water repellent) coating to down plumes to reduce their susceptibility to moisture collapse when exposed to high humidity or condensation.

Cinchable Footbox

You can open up the Cinder quilt completely flat to drape over you, which is a nice option when it’s really hot, to easily stick your feet out the bottom to cool down. When using the quilt closer to its rating, you can cinch up the foot drawcord and it pulls the end of the quilt downwards to close it off. I would really call it a foot “cap” more than a foot box. You can snap together the lowest snap on the sides, but the bottom of the footbox, where many other companies’ quilts would close with velcro or a zipper partway up your legs, remains open.

The Cinder footbox is designed this way to fit over the end of different shaped sleeping pads; just tighten or loosen the cord to fit. I tried it on both the tapered end of an inflatable pad as well as the wider, rectangular head end, and it worked on both. However, one aspect of this design is that it loses a lot of the quilt’s length. Part of the length is taken up by the end folding over, and the fact that this hugs the end of your pad means that more of the length is taken up in creating the footbox height.

If the footbox feels tight, you can loosen up the cord to get more height, but this again uses more of the length of the quilt. I’m 5’4”, and for me, the Regular length quilt works fine, but if I was more than 5’6” I would want to get the long version, despite Sea to Summit recommending the quilt for users up to 6 feet tall. The regular quilt is 6 feet long when completely flat and that just doesn’t leave enough length for the footbox to accommodate a pad and still be long enough for taller folks.

If you don’t want to connect the quilt to your pad, and just use the footbox for your feet, the opening on the bottom is usually flush with the pad, but you may feel a draft on your feet if you move around a lot in the night. I haven’t found it to be an issue at the temps this bag is rated for, though. You will enjoy more usable length using the quilt this way

Oval Shape

The Cinder quilt, when laid flat, looks like a flat-topped oval sitting on a small rectangle (the footbox). The quilt is widest in the middle, which is helpful for side sleepers and those who move around a lot, to keep the sides tucked in and prevent drafts. It is spec’d at 59 inches wide at its widest point, but I measured it to be 56.5. Interestingly the other two width dimensions were slightly under-reported by the manufacturer.

Neck Design and Mitten Pockets

There is a static (non-elastic) cord with a cordlock on one corner of the head end of the quilt on the outside of a mitten pocket, to draw the quilt in around your shoulders. The cordlock is captured so you can tighten it with one hand, a nice feature for adjusting your quilt quickly at night.

There is no draft collar and no dedicated neck snaps, but I discovered that I could connect the two “Quilt-Lock” snaps (located on either side of the center of the top edge of the quilt) around my neck, and then tuck the extra quilt under my shoulders. There are 18.5 inches of space between the two snaps, so if your neck is bigger than that, this won’t work, but if your neck is smaller, you can still cinch the cord smaller while the snaps are connected.

Personally, however, I never use neck snaps or a neck cinch on a summerweight quilt. I much prefer just wrapping up in it. The Cinder is especially nice to do this with, due to mitten pockets on either corner of the head end. You could also use these to wrap the quilt around you like a shawl in camp. If you sleep with your hands up near your head instead of down by your sides, these make it easy to wrap the quilt around yourself and snuggle down. As a side and stomach sleeper, they go a long way in helping keep me covered as I move about.

Connecting two Sea to Summit quilts together into a two-person quilt

Sea to Summit says you can connect two of their quilts together with the snaps on the edges to make a couple’s quilt. However, while I don’t have a second Sea to Summit quilt to test this with, I don’t think this will work well in practice based on what I observed when I snapped the two sides of the quilt together. The snaps are spaced widely apart down the length of the quilt and are located right at the edge, so there will be big gaps between the snaps with no baffle to close them, so whenever one partner moves in the night, you will get a bellows effect of warm air escaping through these gaps. You’re better off getting a dedicated couple’s quilt or just having each person use their own quilt.

Quilt-Lock System

Stacking quilts and sleeping bags is a good way to maximize the temperature range you can sleep in while minimizing gear expenses. As insulation is additive, putting your summer quilt over your 3-season sleeping bag pushes its usability into colder temperatures, just like throwing another blanket or comforter onto your bed at home. One downside of doing this is the clumsiness of trying to manage the insulation stack. Nylon, used in most quilts and bags, is very slippery.

In 2021, Sea to Summit started adding mating snaps to all of their sleeping bags and quilts so you could stack them and they would stay put. On the Cinder, the snaps are on either side of center at the head end, 18.5 inches apart. I don’t own another Sea to Summit bag so I haven’t been able to test this feature. The quilt further “locks” on top of the sleeping bag with the adjustable footbox and pad straps.

Waterproof-Breathable or Water-Resistant?

Sea to Summit describes the Cinder’s shell as “waterproof-breathable NanoShell fabric.” Waterproof-breathable is a terminology usually used for rain jackets with a membrane, or Gore-Tex shelled mountaineering sleeping bags. I have never before seen a backpacking quilt described as waterproof-breathable, so this piqued my interest to research further.

Elsewhere on the Sea to Summit website, I found a description of NanoShell as follows: “NanoShell™ is a 20 Denier Nylon fabric with a water-shedding DWR finish on the exterior and a microporous PU coating on the interior. This highly breathable, highly water-resistant, windproof shell fabric is used on the Sea to Summit Alpine sleeping bags and Cinder quilts where it protects the down from external moisture even during very wet conditions.“

Water-resistant, not waterproof. So don’t intentionally subject this quilt to moisture, or camp out with just a tiny tarp or rain jacket propped up over your head and the quilt exposed to the rain. Many quilts and sleeping bags have a DWR (durable water repellent) coating on the exterior fabric. With this and the use of water-repellent down, the decision to use a microporous PU (polyurethane) coating on the interior of the fabric seems unnecessary. PU fabric coatings also have a tendency to break down over the long term, especially when exposed to moisture. Regardless of the condensation it sees, a summer quilt will be subject to perspiration, so be sure to fully dry this quilt by hanging it up after each use.

Pad Straps

There are four pad attachment straps made of grosgrain ribbon with flat, low-profile buckles in the middle and snaps on either end that mate with snaps along the edges of the quilt. You feed the strap ends through little ribbon loops and then connect the snaps. These loops are to help prevent you from popping the snaps off in the night, and they do that task well. There are 5 pairs of snaps, but usually, I snap the bottom set of snaps together to extend the footbox.

The pad straps of the Cinder are designed to go under your sleeping pad and cinch the sides of the quilt tightly to the sides of the pad to eliminate drafts. Think of it like tucking the foot end and the sides of your comforter at home under the mattress. This setup is very effective at eliminating drafts, but, for a rotisserie sleeper like myself who tends to untuck all sheets and blankets at home to wrap up in them–and do the same on the trail–it feels very restrictive. If you tend to stay in one position for the whole night, it shouldn’t be an issue, and if you like that “tucked-in” feeling, you’ll love it.

Keep in mind that, since the buckles go underneath the sleeping pad, there is no way to adjust them in the night, so you may want to play with the system at home first to determine the sweet spot of strap length that will keep the quilt snug to the sides of your pad without trapping you inside and making midnight bathroom runs an escape act.

You can also use the straps to snug the quilt around your body, taking advantage of the variable girth (ability to wrap yourself tight or loose) that is such a strong feature of quilts. This also provides easier access to undo the buckles quickly. But honestly, at the temp rating of this bag, I’m more likely to not use straps at all, or to just use one around my waist to keep the sides snugged.

Temperature Rating

Comfort in a sleep system is a complex equation with many different factors at play. It is highly subjective and variable. I tend to be a cold sleeper and I found the 50*F rating to be reasonable. I would tend to use this quilt in warmer temperatures, or when 50 degrees was the lowest expected temperature on a trip, rather than the consistent average temperature. I used it a few times in the high forties, and I needed to wear my puffy hooded jacket to supplement the insulation.

Comparable Warm Weather Quilts

Recommendation

The Sea to Summit Cinder Down Quilt can be a good addition to your sleeping bag quiver If you frequently have the experience of sweating through hot summer nights in your too-warm 3-season quilt or sleeping bag. You’ll save a ton of pack space and may even be able to downgrade your pack size in the summer.

The design of attaching the footbox to the end of the pad and the straps below it makes for a secure sleep system that is very good at reducing the draftiness of quilts. It works well for back sleepers who don’t move around in the night, or people who like their covers tucked tightly. This setup also means there is more dead air space you have to heat up, but it is a summer quilt so that’s not as much of an issue as it might be if it were rated for lower temps.

Those who rotisserie sleep or prefer to wrap up in a quilt will appreciate the hand pockets and will want to use the quilt on top of a pad, with just their feet in the footbox and the quilt wrapped around them.

People who are taller than 5’6” should consider going with the Long version of the quilt to have enough room in the footbox.

As expressed above, I think the quilt coupler is a feature that deserves rethinking, and I have questions about the need for a PU coating on the inside. But neither of these features take away from the overall performance of the quilt.

About the author

Disclosure: Sea to Summit provided a quilt for this review.