Bushwalk Australia

I previously posted about the relative strength of polyester and silnylon after exposure to the elements for 500 days. The silnylon was much weaker. At the time I did not have a control silnylon test sample, so the question was raised, by others as well me, about the relative strength of silnylon when new. Consequently, this post compares the strength of polyester and two silnylon tent fabrics when new.
The test samples were sewn as formed double-layered lay-flat tubes that were 30mm wide with sewn load-bearing hems at each end.
A 20L bucket was suspended from one end of the test strip and 10L of water was added to the bucket. Then additional 2L of water was added using a 2L jug. The additions were continued until the bucket was ~full (~18L) or the test sample broke. The testing was recorded in three short videos:
Polyester (silver) load test:

Silnylon (grey) load test:

Silnylon (orange) load test:


The silver-coated polyester and grey ripstop silnylon supported the 18L, while the orange silnylon failed between 14 and 15L of load. I concluded that the polyester was every bit as strong as the ripstop silnylon and I also know that this strength will persist for 500 days of exposure (unlike the silnylon).
For more details please see my full post:
https://timtinker.com/polyester-strength-for-backpacking-tents/
Polyester strength for DIY backpacking tents
https://timtinker.com/polyester-strengt ... ing-tents/

Tim

What are the weights of the compared fabrics?

Last wrote:What are the weights of the compared fabrics?

Hi, Thanks for your question. The silnylons were left-over from my tent-making and were about 40gsm. The silver-coated polyester was the lightest that I could purchase at the time (at an affordable price for my DIY tent experiment) and is about 58gsm. I and sure that a lighter fabric would suffice.
Your question and other similar ones on other forums have caused me to consider testing the fabric to destruction to see if there is a correlation between fabric gsm and maximum load. I expect this may be the case. Who knows? "I just need a big enough bucket for the polyester and the grey silnylon." I think such high breaking loads are not practically important in good tent design, but curiosity has got the better of me! Other fabric functionalities become more important as all the fabrics have enough strength (when new). Tim

Hi Tim, more nice work.
Keep up the good work boyo.
I think fabric gsm is a factor but not neccesarily the only one. Some fabrics are for example stronger than heavier fabrics.
Very interested to see what you do next.

Lamont wrote:Hi Tim, more nice work.
Keep up the good work boyo.
I think fabric gsm is a factor but not neccesarily the only one. Some fabrics are for example stronger than heavier fabrics.
Very interested to see what you do next.

Hi Lamont, I will be interested too! I think that taking all the fabrics to their breaking point will be simple and informative and possibly entertaining. Tim

That test is relevant when comparing those two exact fabrics but not so much when comparing polyester with silnylon because both have very different grades.
For example ,

Franco wrote:That test is relevant when comparing those two exact fabrics but not so much when comparing polyester with silnylon because both have very different grades.
For example ,

Hi Franko, I wanted to compare the load-bearing capacity of two alternative tent fabrics that are very different. My test is crude but valid and gives an objective measurement. The tear or rip video test is interesting, but not relevant and has mo objective measurement. Tim

telemarktim wrote:

Franco wrote:That test is relevant when comparing those two exact fabrics but not so much when comparing polyester with silnylon because both have very different grades.
For example ,

Hi Franko, I wanted to compare the load-bearing capacity of two alternative tent fabrics that are very different. My test is crude but valid and gives an objective measurement. The tear or rip video test is interesting, but not relevant and has mo objective measurement. Tim

The reason for my reply was to point out that there are many very different types of silnylon just as there are many types of polyester and DCF and so on.
You cannot judge a fabric by testing just one particular version.
As the ad used to say "oils ain't oils..."

Franco wrote:

telemarktim wrote:

Franco wrote:That test is relevant when comparing those two exact fabrics but not so much when comparing polyester with silnylon because both have very different grades.
For example ,

Hi Franko, I wanted to compare the load-bearing capacity of two alternative tent fabrics that are very different. My test is crude but valid and gives an objective measurement. The tear or rip video test is interesting, but not relevant and has mo objective measurement. Tim

The reason for my reply was to point out that there are many very different types of silnylon just as there are many types of polyester and DCF and so on.
You cannot judge a fabric by testing just one particular version.
As the ad used to say "oils ain't oils..."

Hi Franko, I am not judging all fabrics. I am just comparing the two ripstop silnylons and the polyester umbrella fabric that I have on hand and have been using to make tents. I only concluded that; ".....that the polyester was every bit as strong as the ripstop silnylon...." . Tim

"Hi Franko, I am not judging all fabrics. I am just comparing the two ripstop silnylons and the polyester umbrella fabric that I have on hand and have been using to make tents. I only concluded that; ".....that the polyester was every bit as strong as the ripstop silnylon...." . Tim"
Yes, you concluded that those two particular fabrics are as strong as each other but not that polyester is as strong as silnylon.
Take a look at , for mexample, what Hilleberg have to say about their silnylon :
https://hilleberg.com/eng/about-our-ten ... -strength/
and this is what Tarptent has to say about their choice of fabrics : https://www.tarptent.com/buyers-guide/
For several years many were asking why TT was not using polyester.
What was not known was that TT had been and was still testing different versions of it and eventualy found a type that works for them.
In fact they also have been testing the same way different types of silnylon and DCF as they are of another fabric that hasn't been used as yet.
This is the type of tear strength machine they use :

obviously they would not need to spend time doing that if all abrics of the samer material were the same.
This is the type of Hydrostatic Head Tester used :

I just read this comment from Ron Bell(owner/designer at MLD) poatede on Backpackinglight :
A note to not over focus on the Denier of the fabric. I know most folks here are fairly well informed on the range of differences in strength and stretch for any set size of Denier in that one 10D SilNylon/Poly/ PU one side , etc. may be great and another one that looks on paper to be about the same not so much. I recall the first time looking at a swatch + spec list of 40+ 10d-20d light fabrics from a single manufacturer listing denier, tear strength, weave density, weights, coating, + even the twist and filament count of each thread, etc. and it was baffling the lack of predictable consistency between the 40+ listed. Some 10ds were more than 2X as strong as other 10d’s that weighed the same. Some 20d’s were weaker than some 10d and 15d’s that weighed less. Some stretched like a rubber band and others not. It makes it hard for a consumer to figure out apples to apples from specs and descriptions but it’s not the mfgrs are trying to make it hard – it’s just hard, even for them. Most all tent mfgrs are doing a pretty good job at getting the best fabrics at a given weight and coating for thier tent goals. Some favor more strength over lighterweight / lighter coating and that may be about the only metric that ends up mattering for most consumers.

Franco wrote:I just read this comment from Ron Bell(owner/designer at MLD) poatede on Backpackinglight :
A note to not over focus on the Denier of the fabric. I know most folks here are fairly well informed on the range of differences in strength and stretch for any set size of Denier in that one 10D SilNylon/Poly/ PU one side , etc. may be great and another one that looks on paper to be about the same not so much. I recall the first time looking at a swatch + spec list of 40+ 10d-20d light fabrics from a single manufacturer listing denier, tear strength, weave density, weights, coating, + even the twist and filament count of each thread, etc. and it was baffling the lack of predictable consistency between the 40+ listed. Some 10ds were more than 2X as strong as other 10d’s that weighed the same. Some 20d’s were weaker than some 10d and 15d’s that weighed less. Some stretched like a rubber band and others not. It makes it hard for a consumer to figure out apples to apples from specs and descriptions but it’s not the mfgrs are trying to make it hard – it’s just hard, even for them. Most all tent mfgrs are doing a pretty good job at getting the best fabrics at a given weight and coating for thier tent goals. Some favor more strength over lighterweight / lighter coating and that may be about the only metric that ends up mattering for most consumers.

Hi Franko, That all sounds quite sensible as fabrics are very complex to us 'mug MYOGers'. The disproportionate lack of saving in weight as 'D' goes down is perplexing to me. So often I need to have the fabric in my hands to truly understand its real properties. For tent fabrics, my personal priorities are; sewability and a little glueability, waterproofness for shedding rain and snow, low condensation, low wet stretch, load-bearing strength, longevity (with lots of use) and of course lightweight. Regarding fabric weight, I have found that a slow-drying tent made of 40gsm fabric may have more 'pack-weigh' than a similar tent made of 55gsm fabric that dries quickly on cold mornings. So fast drying would also be on the list. Tim