Leather under a microscope

[spectre6000]

I believe the briefcase to be undyed full grain vegetable tanned cow hide. The mahogany colored prototype Moleskine cover is the same, just heavily oiled and with lots of intentional UV damage/coloration. The difference between the two extends beyond just coloration, but it's tough to say without having an unoiled and UV colored sample to compare it to. Unfortunately, my hide stash is deeply buried for the next few months due to a home construction project, or I'd have another large pile of pretty much untouched leathers to analyze.

Also interesting, is that statement with the context that there's shell cordovan in the mix. Often considered the highest quality you can get, but I guess it's not the most natural looking owing to the cordovan process. The superficial similarity of the surface appearance of the cordovan and the heavily worn wallet was a big surprise to me.

Something I'm trying to contextualize in my mind in light of that particular comment... The jacket scene seems to mostly pick up in the 30s. I believe the high end leather fashion favored very pale, white leathers prior to that. That statement may have some regionality/siloing to it though. The briefcase leather is probably most representative of that. Those very pale leathers would be undyed, and not subject to UV coloration. The tanning process would also have been very mild. I imagine higher end leathers of that era would have looked more like the briefcase leather than not. Shell cordovan in that period was considered working man's boot leather, and not the prized material it is today. I wonder what it would be like to handle a high quality leather of that era compared to the high quality leathers of today.... Style to style, but also within the same style finish.

 

[sweetfights]

Thank you for taking the time to do this. Very interesting.

 

[Will Zach]

I agree, cool stuff. The microphotographs of various surfaces can tell a lot about leather finishes, weathering, etc. Microphotographs of leather cross-sections would tell a lot about fiber density, leather flexibility etc, but I'd hate ask the OP to start cutting up his jackets and wallets, lol.

 

[spectre6000]

I'm hoping to get a pile of swatches from Fivestar soon. When I do, I'll be looking at them under the microscope for my own curiosity's sake and as a datapoint for specifying a jacket I'd like them to make for me. Cross sections will be very easily visible in that case. Additionally, they'll be more directly applicable to the jacket subject matter of the forum.

Further, if anyone wants to send me a sample of something, I'm happy to image it and post. Doesn't have to be a whole jacket or anything like that. A square inch or so is enough to fill the frame and find it to get it in frame in the first place. Maybe if you have some scraps left over from having something taken in, or have some jacket appropriate hides laying around like I know a few people do.

 

[Canuck Panda]

I've got tons of hides, it'd be interesting to see them under the lens, different animals, different tanneries, different tannage. let me put together a package this weekend. The only thing that may skew the results is some hides I will only be cutting from the perimeter and some hides are left over I can cut from the center of them. Just from naked eye and hand feel the perimeter part feels a bit different than the center of the hide.

 

[spectre6000]

I've got tons of hides, it'd be interesting to see them under the lens, different animals, different tanneries, different tannage. let me put together a package this weekend. The only thing that may skew the results is some hides I will only be cutting from the perimeter and some hides are left over I can cut from the center of them. Just from naked eye and hand feel the perimeter part feels a bit different than the center of the hide.

PM me.

You are correct. The leather from the edges will almost certainly appear different due to stretching during drying. I can also imagine there might be a difference in terms of chemical action, as the edges are thinnest (they finish "cooking" earlier than the thicker back sections), have more fuzz to them since they're less dense, would be the last parts to dry, and probably a few other reasons that aren't immediately coming to mind. No idea how this would manifest under the scope.

Additionally, leather along the spine is tougher and less prone to stretching; it's often used for belts (both machine, and clothing), for example. Bellies are very stretchy, and in my world are often scraps and flaps. You could use them for decorative details that don't get much in the way of mechanical stress. Again, no idea if there would appear any differences visually under the microscope though.

 

[Canuck Panda]

I've got lots, some I know for sure it was air dried (with heat), some are vacuum dried, some toggled dried so stretched, also in heat, some I just don't know but mostly I wonder what is the fiber structure difference between animal species. It'll take me a while to put together the sample package, but this is definitely interesting.

Also most horses I have are fronts, with some stripes right before the shell. Bovines (steer and bison) will be both sides and fronts I will try to indicate which part it came from, from front or the rear bend. Got some sheep and elk and maybe some early goat from 5*. It'll be a while to sort them through but this is gonna be interesting.

 

[spectre6000]

Interesting indeed! I've done a lot of work with cow, some with shearling, but that's about it. I've been digging around trying to figure out the differences between the hides from various species for this jacket, but most of what I have found reads like marketing garbage.

In response to your offering up samples, I just bought a 3-axis eyepiece mount for my phone. The camera I have on the scope is good for watchmaking and electronics, but sucks for high magnification imagery. The hardest part is getting the phone in just the right place, and holding it still enough to get something that makes any sense visually. Kinda pricey, but maybe my 4yo and -5mo will get some use out of it for school projects or something. Maybe just inspire a love of science!

 

[Will Zach]

If you can reliably tell horsehide from cowhide by microscopy, you'll be a TFL hero....

 

[spectre6000]

Oh really? Gauntlet thrown, I guess. No promises, but I'll see what there is to see and share what I find! The only horse I have is shell cordovan, which I've already shared, but that's a pretty special case.

 

[Will Zach]

Oh really? Gauntlet thrown, I guess. No promises, but I'll see what there is to see and share what I find! The only horse I have is shell cordovan, which I've already shared, but that's a pretty special case.

The discussion of differentiating unlabelled horse vs cow has been going on for a long time. It is quite difficult, because different tanning methods muddy the waters. Horse fibers are generally denser though.

 

[spectre6000]

Horse fibers are generally denser though.

That’s my understanding. I’m trying to think back to the living horses and cows I’ve interacted with to try to remember if/how their coats differ. I don’t think I have enough experience to know one way or another though. Additionally, unless I have several samples of each, it may be difficult to tell the difference between, say, a horse and a hairy cow…

 

[Will Zach]

That’s my understanding. I’m trying to think back to the living horses and cows I’ve interacted with to try to remember if/how their coats differ. I don’t think I have enough experience to know one way or another though. Additionally, unless I have several samples of each, it may be difficult to tell the difference between, say, a horse and a hairy cow…

I meant fibers in the hide.

 

[spectre6000]

I knew what you meant, but even IF I'm able to see some sort of definitive difference in the fibers within the hide, that's not really going to help anyone that a) doesn't have a microscope, and b) doesn't want to cut a slice out of a jacket to try to figure out how it looks inside. Hair follicles or pores may still require a microscope, but at least wouldn't require any destructive means to be able to see them. Might even be able to get away with a magnifying glass or something.

 

[Canuck Panda]

I thought about the best way to get you samples. So I will cut a small piece and put it in a letter envelope and write on the envelope what it is. Tagging the individual leather sample would be too time consuming and I'd never get around to go through with it. Will DM you about shipping when I get to that stage.

 

[spectre6000]

Beautiful! That looks like quite a selection!

Whatever is easiest while still getting the idea across. All that matters is the communication.

 

[jr30]

I'm blown away: I was that person who asked a simple question about leather care and got an insight into a material (leather) that I had never seen from this perspective before.

Incredibly great pictures! I'm excited. Great that you created this thread!!!
Roman

 

[spectre6000]

Glad I could make your day! It sounds like there's plenty more to come.

The eyepiece phone mount showed up about an hour ago. It looks promising. I sprung for the fancy one with the multi-axis micrometer-style adjustment and remote trigger. Hopefully it ups the quality going forward. I obviously haven't used it yet, but hopefully it allows me to rapidly burn through CanuckPanda's leather library! With any luck, I'll also get a healthy selection from Fivestar. By the time I make it through both of those stacks, I think we'll probably ALL have had our fill of leather microscopy!

 

[spectre6000]

@Canuck Panda 's package arrived today, and I did my thing! Mostly. There are still a few things I want to do since I have samples that I can easily view from more than just the surface.

Tonight, I'm just uploading the images. I'll probably come back in the morning or soon after to edit the posts with any analysis I have to contribute.

EDIT: It's coffee time the next morning, so I'll try to get some progress done on this project.

The process this time around was a bit more streamlined. I purchased a device to mount my iPhone (or any smartphone, I suppose) to an eyepiece. It has... I was going to say micrometer adjustment, but it's pretty crude screws in actuality. Anyway, one of the challenges with taking photos through an eyepiece with a phone is getting the phone in just the right place. With your actual eyes, it's pretty intuitive. With a phone, you have to get it in JUST the right place, and everything moves the opposite direction you expect it to. Then you have to hold it super stable and still while you press the button, which moves the phone slightly. It's a PITA, but I can get higher magnification and better resolution than I can with the trinocular port camera. The mount allows fine positioning of the camera, and holds it still.

The downside to the mount is that it's a bit of an operation to set up, so once it's on an eyepiece, you want to keep it there. So I set it up for each eyepiece, then ran through the samples positioning them, adjusting focus, and taking photos. As a result, the features in the image aren't the same across all magnifications like they were in the previous run. Doesn't really change much in my opinion, but I figured it was worth noting.

I guess a second downside is that for some reason, with the 30X eyepiece in place, I could not get a full round image. I'm not really sure why that was. You can see the 20X eyepiece image creeping off to the right as well. If I moved the phone to accommodate this, the focal point of the image wouldn't work. Kinda weird. Hopefully I can figure out what's going on in future rounds.

Now, back to the original post.

In keeping with the established presentation mode, here are the microscopy photos for the new batch:

 

[spectre6000]

Horween Wapiti (Elk)

Macro:

90X:

180X:

270X:

I've never seen elk leather before, but I've seen many, many elk living where I do. Pretty sure they have hair, and it's not just my glasses prescription. Despite this, the above images are notable for their lack of pores. I'm pretty sure this is a hallmark of "corrected" leather. I've seen it referred to around here as "stamped" leather as well. The top grain with all its pores, scratches, scars, etc. is shaved off, something waxy/plasticky is applied, and then it's run under a roller or something that flattens everything out and/or applies some sort of grain/texture. I imagine this is because elk are probably usually wild critters (I know they're farmed some places in the world, but it seems hunter's meat processors would be more accessible to Horween; I could be wrong here though). This set of images reminds me a lot of the watch strap on the previous page, only with more of whatever the waxy stuff is applied more evenly. Similar texture (albeit with more of the waxed parts and less of the interstitial fuzzy features), coloration, etc.