Joe: Thanks for taking that question on for me while I was out and about- I appreciate it.

Primaloft is a short staple insulation and Climashield is a continuous filament insulation. By virtue of the fibers that make up the insulations, a rule of thumb is that Primaloft is softer and drapes better while Climashield is better able to span large areas with little stabilization.

In general I prefer primaloft for apparel because drape and softness are important to me, while Climashield’s main strength - the ability to span large areas with little stabilization - doesn’t really come into play.

That said, this new breed of continuous filament insulations are a big improvement over earlier iterations like delta (clo .68) and especially 3D (clo .63).

For a given insulation, the higher the basis weight the warmer it will be. You can determine the total CLO for the item by multiplying the basis weight by the clo number. This will also allow you to compare and contrast between insulations. Combat is a Berry compliant version of XP with a clo value of .78.

Here’s a reprint of an earlier post I put together that will step you through using CLO numbers to compare and contrast insulations

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The whole point of clo numbers is that they are an objective, reproducible, and independent rating of the thermal properties of an insulation. Using clo numbers you can compare and contrast the thermal efficiency of insulations.

Lets consider a case that zeros out the impact of other factors besides clo in an attempt to determine if it takes a lot of fabric and a big percentage difference in the performance of the insulation to affect a significant performance/weight change. Here’s a concrete example of the impact of three insulations, 3D, XP, and Primaloft Sport, chosen because all things other than the clo value will be for all practical purposes equal, and because the project uses a modest amount of fabric (2 sq yds).

My Maxima Jacket pattern in size large uses almost exactly two square yards of insulation: 2.02 square yards.

If you use a 3 oz basis weight of XP and a 3 oz basis weight of 3D, the total clo for each case is as follows:

3D: 3 oz * .63 = 1.89

XP: 3 oz * .77 = 2.31

This is a 22% difference in the total clo of the jacket: (2.31 - 1.89)/1.89 * 100%. All other aspects of the construction would be more or less equal: both are continuous filament and would require the same amount of quilting (only at panel edges), and both jackets would be the same weight since the same basis weight of insulation was used (3 oz) and assuming you make the other parts of the jacket from identical materials. 22% is a pretty significant amount.

Compare this to the same case where a short staple insulation, Primaloft sport, is used instead of continuous filament in the same basis weight as before (3 oz)

Primaloft sport: 3 oz * .74 = 2.22 total clo. There isn’t much difference between the total clo of the primaloft sport and the xp (4%), but there is a pretty significant difference between it and the 3D (17%).

In the case of primaloft sport, the official guidelines for stabilizing it call for unquilted areas to be an area of 2 square feet or less. For our example, the jacket, this requires three quilt lines: one across the back at the armpits, and one on each of the two sleeves. I have Maximas I use regularly made from primaloft sport and XP that were made specifically so that I could subjectively size up the two insulations use in apparel, all other things being equal. Three lines of quilting is quite modest, and I didn’t notice any impact. I don’t notice any difference in warmth of the two jackets which is what I would expect given that the clo numbers are about the same. This further supports the idea that for all practical purposes the methods of construction are the same, making a comparison on a clo to clo basis of the two jackets a reasonable thing to do.

I *did* notice, as I have before, that Primaloft sport is much softer and feels better in a jacket than the stiffer continuous filament insulations.

Lets look at it from a different angle to determine the weight impact of the three insulations for a given clo value, all other things assumed to be equal.

In a size Large of the maxima jacket, the weight of the jacket exclusive of the insulation is about seven ounces.

In working with synthetics the following clo-warmth chart will help:

total clo approx temp rating

2 40’s

4 20’s

6 single digits

If I wanted a jacket to be warm down around freezing, I’d need a total clo of about 3*.

For XP, this means I’d want to come up with 3/.77=3.9 ounces of insulation per square yard.

For 3D, this means I’d want 3/.63 = 4.8 oz of insulation per square yard

For Primaloft sport, I’d want 3 / .74 = 4 oz of insulation per square yard.

(* I realize that the approx temp chart is subjective as it is based on my own experience with synthetics. You can subjectively call total clo of 3 any temp you want, it won’t affect the rest of the argument)

Given that there are about 2 square yards of insulation required for the project, this means that the insulation in the jacket would weigh:

XP: 2sq yds * 3.9oz/sq yd = 7.8 oz

3D: 2sq yds * 4.8 oz/sq yd = 9.6

Sport: 2sq yds* 4 oz/sq yd= 8 oz

Lets add the various insulation weights to the base weight of the jacket in size L to get the projected weight of the jacket with the different fills:

XP: 14.8 oz

3D: 16.6 oz

Sport: 15 oz

So by going with either a high efficiency continuous filament insulation or primaloft sport as compared to 3D you save 1.6 - 1.8 oz respectively .

Or, looking at it another way

A Maxima made from XP is 12% lighter than one made of 3D: (16.6 - 14.8)/14.8 * 100%

A Maxima made from Sport is 11% lighter than one made of 3D: (16.6 - 15)/15 * 100%

A Maxima made from XP is 1.4% lighter than one made from Sport: (15 - 14.8) /14.8 * 100%