Fiber Arts Friday – Alpaca Fiber Tensile Strength

My fiber week was spent back to what I like doing the most.  Making ropes for mecate reins, leashes or lead ropes and of course my fiber of choice is alpaca.  But why?

When I got into raising alpacas everyone told me how much better alpaca fiber was for one reason or another and I wanted to do the research and find out if folks were just blowing smoke up my @$$ or not. It turns out there was hardly any research done and I only could find 1 article done by the Yocom-McColl Testing lab, Texas A&M and University of Wyoming entitled “Fiber Characteristics of US Huacaya Alpacas.”

I specifically wanted to learn about fiber strength.  I was not interested in crimp, color, diameter, or any other characteristic unless it directly affected the strength of the fiber.

First and foremost; how is strength calculated and what is is the minimum needed for today’s high speed mill industry?  Strength is calculated in Newtons/kilotex (N/ktex) and is the force measured in Newtons required to break a staple of given thickness measured in kilotex. Mother Earth exerts 9.8 Newtons(1kg x 9.8m/s2) and kilotex is the thickness in terms of mass per unit length (kg/km).

Today’s milling industry requires fiber with a minimum of 30N/ktex tensile strength for processing.


Wool fiber has a direct correlation between fiber diameter and staple strength.  So much so that Australia research actually has come up with a formula for breeders to follow to improve upon tensile strength.  They can use the CVD (Coefficient Variation Standard Deviation) from fiber reports to improve upon N/ktex.  Breeding for a CVD of 19% or lower creates a stronger wool fiber.  In other words, say your ewe’s mean micron count is 20, breeding to stay within 19% of 20 is ideal for fiber strength. Wool breeders aiming for this CVD, results in producing wool with 30-38 N/ktex.

Huacaya Alpaca Fiber

As it turns out alpaca fiber is extremely strong and has no correlation to color, fiber diameter, or length.  It is naturally strong fiber!  So much so that further studies on its strength aren’t even bothered with because 90% of fiber tested scored higher than the 30N/ktex required for the milling industry.  The mean tensile strength of alpaca is 50N/ktex.  The one study I found back in 1997 for Suri show’s their fiber strength to be 44.4N/ktex. I’m now hearing reports that Suri is stronger than Huacaya due to recent breeding practices but I have not been able to find recent research supporting this claim.

One thing when reading through this study that I did notice, is that alpaca fiber strength seems to increase dramatically with animals raised in the Great Lakes and Northeast regions.  I’m not sure if it’s the cold weather, snow, or forage that the alpaca fiber seems to like, but animals in these regions score and average of 56.25N/ktex.  Alpacas from the central, south and western regions scored an average of 47.26N/ktex.  Fiber Diameter does not appear to affect the strength at all over the regions.

  Great Lakes/North East Central, South and West % difference
Average Strength N/ktex 56.25 47.26 15.98%
Average Diameter µm 29.6 27.9 5.7 %

The study does show that alpaca is also nicer than most wools in that the longer the fiber length does not mean courser fiber.  In fact it tends to be reversed.  The longer the alpaca fiber the finer the micron count and again fiber strength does not appear to be an issue.  Long, fine, short or course alpaca scores above the required 30N/ktex every time. 

I hope I didn’t bore you too much and I guess to sum everything up; alpaca is STRONG!

So what have I been doing with my superior strength alpaca?  Making ropes of course.
here are some photos of the crazy process I go through to make the 6’ braided dog leashes pictured here.

alpaca cord rope making 
Shameless Plug… These 2 leashes are available for purchase!
FREE SHIPPING to any Fiber Arts Friday reader who would like to buy one.
Use coupon code:  FAF
Note these are big dog leashes… 5/8″ dimeter.  If you’d like a narrower leash I can make one custom for you.

6' Dog Leash

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10 comments to Fiber Arts Friday – Alpaca Fiber Tensile Strength

  • Thanks for all that info! It’s always good to gain a better understanding of the fiber that you’re working with. Your dog leashes are beautiful, I’ll have to show them to my dog loving friends. Happy Fiber Arts Friday!

  • Hooray for data! As a scientist and alpaca owner I appreciate how you approached the topic to make it less formidable. Thank you for taking the time to write this post.

  • Wow, what an educational article! That was great!

  • Wow. You just brought me back to engineering school. Although Ktex is a new unit for me.

    I hate it when people tell me something is “the best,” but then can’t answer why.

    Thank you so much for sharing the research. Personally, I love it.

  • Wow, I love your post it was so informative, it’s all so interesting! Thanks!

  • Very interesting post, I knew there was a reason I use alpaca fiber! I would imagine your leads are also very soft! Thank you for all the good information.

  • Great article! I love the fact that alpaca fiber is so strong. The dog leads are great too! Have a great day! ~ Mona

  • Wow! What a fascinating topic. I really enjoy your blogs. I always learn so much. Thanks for sharing and doing the legwork. 🙂 Tamara Your leads are gorgeous.

  • What a great post! I’m very curious about your findings with the Great Lakes. Hey, that’s my herd that shows the exceptional strength! You did put a lot of work into this weeks post and it is rock star! I am actually sending some of my Suri to a friend in California who is a Yo Yo Geek. He wants to spin some up to experiment with it’s strength when using a Yo Yo for competition. I’ll make sure that he reads your blog too.

    Happy Fiber Arts Friday!

    BTW, I bought the gray lead. I’ve been eyeing them forever an one of my miniature schnauzers is going to be all sassy in his Alpaca lead. Thanks for the great deal!

  • Thank you for all that information. I find it fascinating to hear about fibre, as I know nothing about it. I don’t spin, but I think finding out about your crafting materials is invaluable.

    I love the leashes by the way. If I had a dog and lived in the US I would buy one!