I was wondering if using 2 layers of 2.5 OZ Climashield XP would be better than one layer of 5 OZ Climashield XP for my camping quilt?

The fact that this insulation has thicker/denser insulation on the exterior and looser insulation in the middle has made me wonder if:-

1. Could extra air be trapped between the 2 Climashield XP layers making the sleeping bag warmer?
2. Could less of the looser sandwich loft in the middle of the 2.5 OZ Climashield mean a reduced deformation and clumping during use and therefore longer performance life when constantly compressed into stuffsack while hiking?

But I also wonder if using 2 layers would mean a denser insulation thus making the quilt/sleeping bag less compressible and heavier?

Any ideas?

Thanks.

Hi Markkit-

The ‘thicker layer’ you’re referring to has a structural function.  It is more or less constant between basis weights.  So for a thicker basis weight of insulation, the amount of the structural layer is a smaller percentage of the whole.
This structural layer has a smaller amount of loft per unit weight.  So two layers of 2.5 XP have four of these structural layers, and as a result a little bit less loft than a single 5.0 oz layer.  Given that within a single type of insulation all things are (basically) equal, the fact that the thicker basis weight version have more loft means that they will be warmer per unit weight. 
If you were making something complicated such as a jacket or bag with a differential cut, or trying to offset quilting, or using some other method where having two distinct layers would be of benefit, then I think it would make sense to use two layers of 2.5.  But if not, it makes more sense to use the 5.0, and as a bonus it will cost less too.

With regards to the durability issues you bring up, use patterns are the main factor in determining useable lifespan.  But in any case, clumping shouldn’t be an issue, especially with continuous filament insulations.  When an insulation has to be aggressively quilted, you can get clumping which really is an indication that the batting has torn.  This most commonly happens with primaloft one because the quilting requirements are so stringent (6 square inches for box quilting, or 3” lines).  It also can happen with primaloft sport but usually only in cases of abuse or if makers have cut corners in the relatively easy quilting requirements (2 square feet).  The primalofts, though, are short staple insulations which makes them vulnerable to tearing if not properly stabilized, a problem that is all but eliminated with a continuous filament insulation like climashield.  This is not to say that one is better than the other in an absolute sense. With apparel the amount and difficulty of quilting for primaloft is very reasonable, and the drape, compressibility, and softness of primaloft are of great advantage, while for large panel items like quilts the material handling ease and small amount of quilting means climashield really comes out ahead.

That makes sense. Thanks.