Evaluation of thermal performance of Montbell Plasma 1000 parkas

Thank you for this evaluation. You are turning to be a highly valuable member of this community!

A lot of knowledgeable folks add value to the site, so I am happy to contribute. If people send me more garments to test, I also get the opportunity to improve my instrumentation and skills.

It’s interesting to see the cerium is warmer. The Montbell certainly seems puffier.

Stephen,

Which basic technique are you using to determine the R-Value: wattage to keep permeation pot at the set temperature or the average bottom temperature – surface temperature (at a fixed room temperature), or none of the above? If it is the temperature difference, how did you calculate the unique exponent to adjust for the fact that temperature difference is not linear with the R-Value?

As I recall, the Cerium has greater loft, although the fill rating (850) , for what it is worth, is less. What I wonder is why does 1000 fill down exist today?  Some years back it did not exist.  The highest fill was 850-900.  Now, there is 1000.  Did the geese change their feathers some how?

What I wonder is why does 1000 fill down exist today?

Since down production is a process of collection, gradation, and accumulation of down clusters of a certain quality, my guess…and it IS nothing but a guess…it that 1000FP is the result of a more painstaking selection/filtering process?

BTW, I love my MB Plasma 1000 :)

Hi Richard:

Can you provide some material properties and relevant temperature ranges in support of the assertion in your post? Particularly, those that relate to the fabrics and insulating materials used for outdoor wear.  I will then respond.

Hi JCH:

A few years ago, Patagonia introduced a chemical treatment that resulted in, to my limited knowledge 1000 fill down for the first time.  That was in 2013.  Read about it here: https://www.outdoors.org/articles/amc-outdoors/the-puffiest-down-jacket-ever-patagonia-unveils-1000-fill-power-encapsil-belay-parka

If you washed it, it was no longer 1000 fill down, so they offered to wash it for you.  I don’t see it offered any more.

At this time, only a few companies offer 1000 fill down.  Montbell, Rab, Stellar Equipment and PHD.  There may be others.  The prices are not so different from jackets with lower fill numbers, so I don’t quite understand where this comes from if further sorting or processing required.  Allied Feather and Down in California lists goose down to 900 fill power. Perhaps someone on this forum has some knowledge on how this material is produced and if there are standards used to ensure the manufacturer’s claims.

I am glad you enjoy  your jacket.  My review was not critical of the jacket’s performance.  It did point out manufacturing differences that were not supported by web site claims.  I presume you are wearing  the men’s jacket, which is manufactured in conformance with those claims.

Stephen,

My assertion has more credence when you understand that it is called “Newton’s Law of Cooling”.

Common outdoor clothing range in insulation values from a base layer like the RAB aeon T at ~.085 Iclo, to heavy clothing insulation like the Canada Goose Expedition parka at ~9.06 Iclo.  Without calibration of your test environment against known (an example is NIST) reference insulation’s over this range, you can’t determine the exponential value to adjust your temperature readings.

Let’s review.  I conducted a steady state evaluation to determine whether two garments had similar levels of insulation.  I concluded they do but were constructed differently, which produced slightly different performance.  What does this have to do with how the insulation might perform at wildly divergent temperatures? At any temperature, the general answer I provided will not change.

I also do not see how a wonderfully insightful set of equations will change the conclusions that I reached.

If you place the garments that I looked at inside the garments you described, the general answer I provided would be the same.

However, if you think your points are relevant,  would you then mind describing how the clo values that you publish acknowledge this temperature dependency?  Would you describe the expected range of temperature related R Value variance for down insulation in a garment over all utilization temperatures? Can you describe  how you incorporate this range  into the comparisons of clo values that you have  published over the years?

You and I both know that we measure performance under static conditions and assume the results will be reasonably relevant under a range of  environmental and other conditions.  However, the uses of garments vary greatly in terms of environmental conditions, fit, operation, exertion levels, user metabolism and more.  Our data can be used as a guide to performance but cannot provide precise data for all known conditions that will be encountered.

If you wish to discuss and compare  the merits of our testing procedures and calibration processes, I would welcome the opportunity.  Collegial  cooperation between us might well result in better results for both of us. This would mean more data for the members of this community to use for their gear decisions.   I have tried to initiate such a discussion with you twice via PM and have never received a response. Perhaps this would be a good time to start that conversation.

Stephen,

Using the approach you described does the following:

-It tells if two garments are equal or different in warmth and which is warmer

It does not do the following:

-It does not tell you the actual insulation value of either garment.

To visualize the magnitude of any insulation value calculations, without temperature delta compensation for Newton’s Law of Cooling, reference the following simple image.

The x axis is the temperature difference and the Y axis is the calculated insulation value  The black line is the calculated insulation value assuming that the relationship is linear and the red line is the actual insulation value based on Newton’s Law of Cooling.

i don’t receive forum messages.

Richard:

I have requested you to provide documentation of your claims.  All you have provided is some wavy lines and claims that lack any documentation.  I will take a stab at this.

Here is Newtons Law of Cooling from Wikopedia:

Newton’s law of cooling states that the rate of heat loss of a body is directly proportional to the difference in the temperatures between the body and its surroundings provided the temperature difference is small and the nature of radiating surface remains same.

Here is the equation:

dT/dt=-k(T-T0)

This equation may be restated as a differential equation and solved.  In no statement of the equations is R-value present.

This equation allows you to calculate the rate at which an object cools to its environment.  For example, if you take a cup of coffee and set it on a table.  Measure the temperature of the coffee.  Let 5 minutes pass. Measure again.  With these two temperature measurements and the known time differential, you can solve the differential equation and determine the time required to reach any temperature down to ambient.

If you plot the temperature versus time equation, you get a graph  that decreases at a decreasing rate.  This is because the rate of BTU loss for each subsequent unit of time is less as Delta T increases.

What drives this phenomenon is convective and radiant heat loss.

In the simplest use of this equation, if you know the starting temperature of the object and the ambient temperature to which it cools, you can measure the temperature drop over any time period and use the equation to calculate the required to drop to any temperature above ambient.

Here is a simple example.  We have an object with a temperature of 100oC.  It is in ambient of 50oC. We know that it cools to 80oC in twelve minutes time.  Let’s plot a curve of the time required to reach zero, showing time and temperature on the way.

We solve this using the following formula:

T(t)= Ts+(To-Ts)e^kt

T(t) =Temperature at time t

Ts= Ambient Temperature

To=Object Temperature

k=constant

We can solve for the constant and then calculate all the values.  The constant, when the equation is solved is -.04257.

Using this constant we can produce the following curve of the object cooling.  On this graph I also show the watts of heat transfer at each time interval using an assumed area.  The watts calculation incorporates radiant transfer at an assumed emissivity and convective cooling for an assumed convective cooling transfer coefficient for heat loss in still air.

The blue line shows how quickly the object cools.  Because we measured cooling for a predetermined interval, all thermal properties of the object are implicit in the rate of cooling.  We do not need to define R value, mass, surface emissivity,  or the convective heat transfer coefficient.  This also means that none of those parameters change during the cooling process.  If they do, the calculated rate of change will differ from the actual.

As we can see from this discussion, Newtons cooling law does not explicitly incorporate R value and cannot actually function if R values were to change. Cooling slows over time because the temperature difference diminishes and less energy per unit time is transferred to the environment. The relationship is elegant and simple.

For typical heat transfer calculations, it is by definition that R values do not change with temperature.  This is inherent in the basic heat transfer equation: Q=u(T1-T2) where

Q=Heat Transfer, u= conductivity, T1-T2 is the temperature difference across the test sample. U is the reciprocal of R value.

However, for a class of materials, where heat transfer may be a combination of radiant, convection and conduction transfer, there may be a temperature dependency on R value.  This class of materials includes insulating materials. The only study of this behavior of which I am aware deals with building materials. An example material is fiber glass batt insulation.  Here is a link: https://www.buildingscience.com/documents/special/thermal-metric-documents/thermal-metric-summary-report

As an example from this report, over a temperature range of 72oF to-18oF, the measured R value of R-13 fiber glass batt insulation varied from R-12.8 to R-14.9.  In other words, a pretty small variation over a wide temperature range.  I suppose this behavior may apply apply to down and other garment insulating materials.  I have not come across any documentation that this occurs. If it does, it is minor.

Based on this discussion, I do not see the merits of Richards claims concerning  Newton’s Cooling Law and the methods I use to measure R value.  Further, for the steady state measurements that I took to measure R value, the temperature dependency relationship described in the referenced document would have no bearing on the conclusions.  The conclusions will stand.

I don’t know if anyone is concerned enough to follow this thread.  However, it might be best to continue this discussion off line. It is certainly getting in the weeds. Richard, if you would like to, please PM me.  Also, if you PM me, I will send you a paper by a colleague (and Phd physicist) that documents a methodology similar to mine for extracting R values using thermal imaging as well as other instrumentation. I would welcome the dialogue. If you have no further expert sources to cite, or a clearer description of what you object to, I am not sure it makes any sense to continue this thread.

Just wanted to chime in and thank Stephen for the evaluation of my garments!  It’s very interesting to me to see the comparison between the two garments with the thermal camera, and the subsequent detailed analysis.

I encourage other people to contact him if you have garments to test.  He mentioned to me that he would be happy to test anything people send him. :)  If enough people did this, perhaps we’d have a meaningful way to compare a number of popular garments since the product specs generally don’t provide any information for any kind of reasonable comparison.  (Fill weight only tells you so much, as clearly illustrated by this analysis).