Why not silk for Apex quilt liner instead of nylon/polyester?

Monte, you’re in luck someone has! Bill Fornshell has many awesome MYOG threads on here and using silk with Climashield is one of them.

https://backpackinglight.com/forums/topic/4262/

https://backpackinglight.com/forums/topic/7132/

https://ultraliteskunkworks.blogspot.com/?m=1

I think the warmth of all liners is the same, insignificant.

The weight is what’s important. You can get nylon that weighs 0.7 oz/yd2.  Maybe silk feels better so the slight extra weight doesn’t matter

And if you have down, whether it’s down proof.

Jerry is correct, liner warmth is a small factor compared to the apex above it.

THE most important factor for sleeping system layers over Apex is the CFM rating of the airflow through the material.

Apex pretty much has close to zero airflow control on its own. 10 ounce per yard apex on top of you without any face fabric to control airflow would leave you feeling like you didn’t have any sleeping system at all and freeze. I literally tested this exact thing, and froze… LOL

So, pretty much most of the downproof UL fabrics would be most ideal, and then just choose on weight and feel. The downproof fabrics are often low CFM materials in the 10D and 20D varieties.

If you want max warmth, go with lowest CFM airflow rating. If you want the maximum ability to dry out yourself and the sleeping system while in bed, then go to higher CFM, at the cost of reducing the overall temp.

I made a silk-lined (nylon outer) quilt many years ago. Back then, 20D nylon was so expensive I did that just to save some money (and some weight too). And it worked great, it feels nice and works well, although it definitely is more fragile.

The light silk is very breathable – as discussed above, because of this, it won’t be warmer than most synthetic materials which are less air permeable.

Now I would consider the silk only if I wanted this breathability – and even then, one can now get synthetics with similar properties and feel too.

Yea Jan, fleece is one synthetic that would probably outperform equal weight silk, at least a little. From the research I’ve done silk is supposed to provide about the same warmth per weight of merino wool. Not as warm as pure wool but much warmer than cotton, and warmer than most synthetics.

The Sea to Summit Reactor series bag liners look and feel like silk and they certainly seem breathable. I don’t understand the materials science behind them, however I find equal weight silk to be warmer, either as a 60 degree summer bag or a bag liner. The temps S2S claims on their Reactor liners is laughable. S2S does make some good stuff though.

So I guess the question I pose is which is warmer, breathable nylon/polyester or pure silk (of equal weight)? I mean in terms of using it as an Apex quilt liner.