Author name: Dan Timmerman

In most cases, adding internal volume to a down sleep system will have detrimental effects on insulation efficiency. It’s usually an inefficiency feedback loop. Increased size promotes sprawl sleeping, which increases heat loss from the body. Then, that lost heat enters the system cavity, but the increased volume increases the lag time before that space […]

We’ve been building and selling our version(s) of false bottom sleeping bags for at least 8 years now (as of 2026). There are many hundreds of them out there by this point. The feedback we receive from people using them has been extremely positive. The original design has been so successful that I don’t recall

Part of the testing I do is keeping tabs on some of the long term usage pieces I have circulating around to see how different aspects are holding up. One area of interest is down loft durability. It is my opinion that in most cases, loft loss observed in down gear is due to oil

If someone is attempting to assess the general insulation of a panel of a down item, they would need to know two main things. On one hand there is measured loft, which is the physical space filled with insulation. The other is the quantity of fill in that space. Both Total fill weight and calculated

If you hold a measured loft constant, but you add more fill to it, density goes up and insulation goes up. That is misunderstood as higher density is warmer. If we reverse it and hold the fill quantity constant but reduce loft, density goes up and insulation goes down. The correct conclusion would be that,