Is leather stronger when laminated with an additional layer of leather?

[thekid77]

Hi friends, 

I was wondering......which is stronger-----a single ply of leather, or two layers of leather laminated together (assume that in either case they both add up to the same weight/thickness)...

Thank you in advance for sharing!!

[Chief31794]

Two layers is much stronger, and somewhat "stiffer".  The "strength" of the leather is in the grain and when you glue them, you have two grain sides resisting each other, they don't bend as well but they are much stronger.

Chief

[thekid77]

1 hour ago, Chief31794 said:

Two layers is much stronger, and somewhat "stiffer".  The "strength" of the leather is in the grain and when you glue them, you have two grain sides resisting each other, they don't bend as well but they are much stronger.

Chief

Thank you for sharing Chief, much appreciated

[thekid77]

12 hours ago, nstarleather said:

"Stronger" and longevity might be too different things, if they actually end up at the same thickness the strength would roughly the same.  With 2 layers you have to worry about that bond (glue) in the center breaking down over time, which would not happen with one thickness. Also if 2 layers are stitched, you add some strength but also the possibility of wear in the stitching.  The only really good reasons to double layer things is to add thickness which does obviously add strength, or if one of your materials is weaker or more stretchy, say lining a Chromexcel belt with something that doesn't stretch like Chromexcel does.  Or you can layer for the "look" of adding a lining, perhaps in a different color than the other side.

 

Thank you for sharing.....so, even if they wind up to be the same thickness,  according to what chief said (see above comment), they are "much stronger" because there are two grain sides resisting get each other....do you agree or disagree with the this?

 

Thank you 

[JLSleather]

Chief has a point, actually.  From a technical view, the grain layer is the strongest part of the leather, so 2 grain layers would be "stronger".  More important, two layers together "pulling against each other" is "stronger" much in the way a braided rope is stronger than a single fiber -- the fibers aren't actually "stronger" (the tensile strength of the fiber would be the same) but the ASSEMBLY is.

 

[thekid77]

39 minutes ago, nstarleather said:

 

I don't disagree but especially if you're talking about shaving off the suede side and adding another top grain to it, of course it's stronger.  I just think that in an actually scenario of using something you have some forces that will break that bond with time. If it's just glue and not stitched, then you can bet one layer is better, any day. 

I 

Thank you for the input.....another question if I may...

From ym experience, when properly "set", contact cement such as dapper weldwood from the red can is virtually indestructible....to get the leather to separate you'd have to destroy the article, whatever it may be, from my experience.......just my opinion, but I feel like dapp doesn't really need stitching to reinforce it....

Thoughts?

[Dwight]

Bluntly, nstarleather is wrong.  

Two pieces of leather bonded with Weldwood contact cement will not come apart and is seriously much stronger than any single layer of leather.

The other side of the single layer is that the flesh side will abrade and wear off much faster and easier than the hair side, . . . so bonding flesh to flesh, only leaves the strong side to weather whatever comes at it, . . . making the overall product a much better product.

I've been using Weldwood contact cement since the late 60's or early 70's and the only time I've ever seen two pieces come apart that were bonded with it is when one of the pieces gives away, . . . whether it is fibers of wood, leahther, formica, or whatever you use.

May God bless,

Dwight

[Big Sioux Saddlery]

There could be two correct answers to this question.  Both can be stronger than the other, depending on end use.  I'm going to refer to horse tack, because that's most of what I make.  For heavy, everyday use, I can guarantee that one, good heavy layer will normally outlast two layers sewn together to equal the same thickness.  I've seen it countless times, two light layers sewn together under heavy use will break down faster than one good heavy layer.  One reason is every stitch pokes a hole close to the edge of the leather, making it possible for dirt and moisture to work it's way into the interior fibers of the leather.  The leather will dry out faster, and it CAN delaminate.  Against the strength of a horse, a little old thread (no matter how heavy) isn't going to add much strength.  I'm sure someone is going to reply telling me I'm wrong, but after 25 years of repair work, that's what I've seen.  I have headstalls out there still in daily use after 25 years. They were made with a single heavy layer of russet Hermann Oak harness leather.  The buckles are darn near worn out, but the leather is still holding.  I do not believe that if I had made them doubled and stitched out of two lighter layers they would have lasted this long.  The first cracks usually to appear in a strap start at the holes.  Think about how many holes are in a strap that is sewn all the way around. That's a lot of holes!  That's why doubled and stitched stuff is generally for "goin' to town" and the single heavy layer stuff is the everyday working tack.  Somewhere in an old book about harness making, the author talked about how injurious a splitter is to leather.  I believe it was in the same book that it was claimed that removing a third of the thickness removes half of the strength of a strap. 

Stirrup leathers on western saddles are a good example. It is common practice in production saddles to sew a one inch wide strip of leather down the center of the stirrup leather where the adjustment holes are located. Within 5 years or less, most of these are coming apart or have already broken.  Too light of a base stirrup leather is used, and then "reinforced" with this strip (usually a strip of latigo) and then when they separate from wear, which I guarantee is going to happen, neither layer is heavy enough for the intended purpose.  Certainly there are instances in other areas of leather working that this would not be the case however, and two layers would outlast one.  But it's not ALWAYS the case.

[JLSleather]

1 hour ago, Big Sioux Saddlery said:

every stitch pokes a hole close to the edge of the leather, making it possible for dirt and moisture to work it's way into the interior fibers of the leather

At last, someone who understands (and admits) the harm done by pokin' holes where they don't needa be nun   That second row o' stitchin' on that fancy go-ta-meetin' holster is basically a tear line.. like scoring concrete ..

1 hour ago, Big Sioux Saddlery said:

doubled and stitched stuff is generally for "goin' to town" and the single heavy layer stuff is the everyday working

Hey, I make quite a bit o'the 'shiny' stuff, but I'm in with ya on the put no holes where they don't needa be.

 

[Les No6]

Single strap is strongest the strength is in the coarse fibres as referenced in the Hasluck books, not the grain that’s just a brain fart or marketing BS as is over 90% of the internet including this website these days.