Is This Correct? Chrome Vs Vegetable Tanning

[Sarden]

Hi,

I'm new to this forum and part of a startup business that seeks to source and promote premier quality leather goods and craftsmanship to a wider audience. I will post a link to our site in the "new members" group.

We want to educate people and help them better understand leather so they'll make informed purchasing decisions ― and we want to improve our own knowledge of leather. Those are the main reasons I am now a member here on Leatherworker.

We have just finished an article about vegetable vs chrome tanning. I would be most grateful if some of you experts would spare 5 minutes, read through it and comment on it. If you have suggestions for changes or adding more information to the article, please let me know.

Thanks!!

Anders

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Tanning leather: Chrome or vegetable?

The leather that your bag is made of has been tanned. And no, that doesn’t mean that it has been left in the sun to get a bit of colour.

Basically, tanning is the process that converts animal skin to leather. How this process is carried out has a very significant impact on the quality of the bag you hope to use for years to come.

Will it soften and acquire a patina over time? Or will it look the same until one day it starts to crack?

Once an animal skin has been turned into a hide by being degreased and having all its hair removed, the tanning process can begin. An untreated skin would both harden and putrefy as it is an organic material. So, the aim of the tanning process is to prevent this from happening – to turn the hide into leather.

This is something human beings have been doing for a very long time. Some evidence suggests that leather tanning was performed as far back as approximately 6,000 BCE in the Indus Valley – one of the cradles of modern civilization.

The basic principle has been the same for all these millennia: To modify the protein called collagen, which the skin is made up of. You can actually get a sense of this protein with the naked eye. Collagen molecules like to first line up and then to twist together into “fibre bundles“, that you can easily see if you look closely enough at quality leather.

Look closely and on vegetable tanned leathers you will be able to see the collagen fibres that leather is made up of.

What tanning does is leave the skin much less susceptible to hydrolysis – the separating of chemical bonds caused by water – which would otherwise cause its degradation. Tanning modifies the molecular structure of the skin.

Vegetable tanning
For the vast majority of the past thousands of years this modification has been performed by soaking the skin in a solution made up of vegetable tannins. These tannins would most often come from trees such as oak, chestnut or mimosa, but hundreds of tree types and other plants have been used. In fact, the word ‘tannin’ derives from an old German word for ‘fir’. So ‘tanning’ has nothing to do with colouring as in getting your kit off and letting the sun brown your skin.

A tannin is a molecule that bonds easily with proteins and will draw liquids out. If you are a wine drinker, you may have had heated debates over a wine’s ‘tannins’ – the ingredient that makes the wine feel dry in the mouth, sometimes to the extent of making both your tongue and gums feel unpleasantly arid and barren. Just as the tannins in wine come from the skin of the grape, the tannins in trees are found in the bark.

When tanning hides to make leather, the hides are soaked in a tanning solution. The tannin molecules will enter the hide and displace the water that is bound in the collagen. The water is drawn out, but as the tannins take the place of the removed water, the leather does not grow inflexible as fully dehydrated leather otherwise would.

It may sound easy, but it isn’t. The process is complex and the skins require multiple treatments over a period of up to two months in order for the water molecules to be fully extracted and letting the tannin molecules take their places in just the right way. A lot of work from skilled craftsmen is involved too.

Mineral (chromium) tanning
The complexity, expense and time involved with tanning with vegetable tannins led to the development of using mineral tanning agents instead. The basic principle is the same, removing water molecules from the collagen and replacing them, but the process is much quicker using chrome which by far is the most popular mineral tanning agent today. The whole process can be automated and finished in a day.

The process, however, is far less natural than when using vegetable tannins. It involves first placing the hides in acidic salts to better make the chrome fit in between the collagen molecules – and then returning the hides to a normal pH level.

This requires the use of acids and other chemicals as well as the chromium sulphates themselves. All these have a negative environmental impact and the industry is under increasing pressure to “clean up”. As opposed to the vegetable tanned variety, chrome tanned leather can’t be recycled either as it is not truly a natural product.

Nevertheless, today no less than about 90% of the world’s leathers are chrome tanned – primarily due to the cost. If you buy wholesale leather, vegetable tanned leathers cost about three times as much as chrome leathers.

In general, vegetable tanned leather is considered far superior to chrome leather.

Look, feel and smell

The cost and environmental impact of chrome and vegetable tanned leathers are not the only differences between the two. There are more visible distinctions too.

Vegetable tanned leather

• Because of the way it is tanned, the colours of vegetable tanned leather will be richer and “deeper” and the leather will appear, as it is, natural.
• Being an entirely organic material, vegetable tanned leather will change over time. It will grow softer and darker, and will acquire a patina depending on its uses.
• As it is more durable, vegetable tanned leather will last longer than chromium leather – potentially several lifetimes. Bags that are decades old can be highly sought after items.
• Vegetable tanned leather scratches fairly easily, but unlike chrome leather, scratches can easily be buffed out.
• Vegetable tanned leather smells natural – the pleasant, sweet smell you probably associate with leather is the smell of vegetable tanned leather.

Chrome tanned leather

• Chrome tanned leather looks a little as if it has been painted – the fibres of the leather not being allowed to show through the way they do on vegetable tanned leather. It is basically a less natural product.
• Chrome tanned leather will not develop a patina but will continue to look pretty much like it did when it was purchased.
• Chrome tanned leather will initially be softer and suppler than vegetable tanned leather but will not age well. Over time it will grow prone to breakage.
• Chrome tanned leather is more resistant to water, stains and extreme heat.
• Chrome tanned leather will have a slight chemical smell to it. Sometimes disguised by the producer artificially scenting the leather.

HOT TIP
Blue chrome

The chrome tanning process will turn the hides light blue. As they are subsequently dyed, the blue will no longer be visible on the surface of the finished leather. But the leather will later be cut into the pieces needed to sew, say, a bag, and the edges of these individual cuts will show a blue tint. Most producers will use a special paint to paint the edges, but if you see any trace of blue edges, the leather in your hands has definitely been chrome tanned.

Edited April 29, 2015 by Sarden

[Sarden]

Thanks a lot for your reply. Appreciate it. The point about chrome tanned leather being suitable for, especially, clothing is a good one. We will add it to the text.

With regards to patina, colour and wear, I have found numerous sources stating that chrome leather reacts the way described in the article: very little patina develops, it doesn't wear well, colours are not deep. Basically every source I have come across describes it this way.

Do you have more information about this? Maybe some online sources? I would be interested in investigating further if it is in fact not true.

[Sarden]

Thanks for another great answer. We will make a few adjustments to the text.

I think, however, that your "Horween Chromexcel" example somehow confirms that vegetable tanning is needed to achieve a good patina. As you say, the Horween is combination tanned, also using bark tannins. So I would deduce from that, that chrome tanning alone cannot produce significant patina.

With regards to the colour richness, here is an example of a page describing this phenomenon: http://www.satchel-page.com/blogs/news/14289793-shh-leather-prices-from-a-tannery

(They also sell jackets made of vegetable tanned leather - or at least 'vegetable re-tanned')

I understand that page is skewed towards vegetable-tanning, and so are we, obviously. But judging from our own leather samples here at our office, I would certianly agree that the vegetable tanned leathers appear more "lively". The slight differences in colour tone add a "depth" to the colour apperance. It seems "richer".

But the softness certainly seems a selling point for chrome tanned leathers.

Thanks again. Really appreciate it.

[Thor]

Besides the fact that tanning and dyeing are two different things and we differentiate at the least between coloring or dyeing the surface or dyeing through the whole and the processes for each are different I find the intro too long as well as the first sentence would put me off already. It may sound funny at first, but what it truly is, is telling the reader to be dumb. It's common knowledge that leather has been tanned. The few people that don't know that are probably not even interested in that fact already.

Mike, isn't Horween using veg-chrome tanned leather (I don't know). That would mean it's chrome tanned an re-tanned using vegetable tanning.

[Thor]

• As it is more durable, vegetable tanned leather will last longer than chromium leather – potentially several lifetimes. Bags that are decades old can be highly sought after items.
• Vegetable tanned leather scratches fairly easily, but unlike chrome leather, scratches can easily be buffed out.
• Vegetable tanned leather smells natural – the pleasant, sweet smell you probably associate with leather is the smell of vegetable tanned leather.

Chrome tanned leather

• Chrome tanned leather looks a little as if it has been painted – the fibres of the leather not being allowed to show through the way they do on vegetable tanned leather. It is basically a less natural product.

All of these 3 points are false statements.

If a person heard of red rot before it's obvious that this would not be true.

If one really scratches leather it doesn't matter whether it's veg or chrome tanned. That scratch is to stay. Minor scratches may be buffed out, but that's no concern.

I'm just thinking of box calf leather, which is a chrome tanned leather and if you add some finish cote there's no difference in smell at all. This statement would only be true in regards of untreated leather. In that case we would be talking about unfinished leather.

For the chrome, this is again not true if reviewing box calf leather. It really depends on the tannery. There are on the other hand veg tanned leathers which will not really show any fibers. Please review anilin, semi-anilin leathers and so on.

I agree with Mike that more sources should be participating in this. A simple Google search will help already and you'll find articles like this one http://maxwellscottlm.hubpages.com/hub/chrome-versus-vegetable-tanned-leather

https://www.google.de/search?sourceid=chrome-psyapi2&ion=1&espv=2&ie=UTF-8&client=ubuntu&q=chrome%20vs%20vegetable%20tanned%20leather&oq=chrome%20vs.%20veg&aqs=chrome.1.69i57j0.8865j0j7

[doe]

I can't comment on the accuracy of what you've written, but I can say that the whole thing seems biased and skewed towards veg tan and that, in turn, would make me skeptical as a novice buyer. I'm happy to be informed about a product's properties, but I don't want to be told what attributes I should prefer. For example, some people may like a more uniform color treatment or a consistent finish that will not patina over time. People may not like the idea of a product that scratches easily or that they have to clean and treat for weather resistance. Putting those biases in your descriptions is a little alienating. A more balanced and neutral list would point out the properties of both and emphasize that different leathers are appropriate for different applications. You can still say you work with veg tan for X, Y, and Z reasons but try to avoid putting down chrome tan in the process.

[Sarden]

<p>Thanks a lot to everybody for your comments.</p>

<p> </p>

<p>We have, of course, done many Google searches in order to research the subject properly. In fact, information from about 30 texts have gone into writing the little piece above.</p>

<p> </p>

<p>The article mentioned above by Thor - <a data-ipb="nomediaparse" href="">http://maxwellscottl...-tanned-leather</a> - was one of those texts. Some of the statements that Thor call false above are also mentioned in that very article.</p>

<p> </p>

<p>That article also states "<span style="color:rgb(51,51,51);font-family:Arial, Helvetica, sans-serif;font-size:13.8000001907349px;">vegetable tanning is far superior!" as well as "</span><span style="color:rgb(51,51,51);font-family:Arial, Helvetica, sans-serif;font-size:13.8000001907349px;">The only real advantage we have found with chrome tanning is that it is more stain, water and heat resistant."</span></p>

<p> </p>

<p>It seems that some of the more critical voices above are in fact involved with working with chrome tanned leather. So just as we admittedly are skewed towards veg tanned leather, could it be that you possibly are a little skewed towards chrome tan for a various reasons?</p>

<p> </p>

<p>Thanks Thor for the comment about the first sentence. I get your point and don't disagree if the target group consists of people like you guys here on the forum. Our mission, however, is to reach a wider audience and inform about purchasing quality. So the target group are people who are interested in leatherware in general but today don't know, nor care much about, exactly what quality they are paying for.</p>

<p> </p>

<p>With that in mind, I hope the opening of the article works to generate a bit of initial curiosity, and, if we are lucky, a little smile. (-:</p>

<p> </p>

<p>I agree with Doe from Chicago that the text can seem biased. It IS biased, I admit. Waremakers (our project) emphasises natural processes and craftsmanship, so we certainly prefer veg tan. But we will have a second look at toning it down a little, as we do understand the advantages of chrome tanning. </p>

<p> </p>

<p>Thanks again,</p>

Edited May 1, 2015 by Sarden

[byggyns]

If you are emphasizing natural processes & craftsmanship, I would suggest including a small section on brain tanning. Brain tanning was, from the research I've read, the original method of tanning hides & furs, and pre-dates veg tan. Chrome tan was really developed to imitate the properties of brain tan in a more economical, repeatable, & mass produced method.

I think that it would benefit you to emphasize that much of the chrome tanned leather on the market is not "full grain" it is "top grain". What this means to consumers is that the top surface has been sanded to remove imperfections and then coated in a finish that changes the texture of the leather. That is what gives the "painted look" you refer to. Full grain leather has the top surface intact, but may be shaved or sanded on the back side. Full grain leather can come in either chrome tan or veg tan. To my knowledge, there isn't a way to make "top grain" veg tan. I think this is where a big divide in the leather quality comes from, more so than the tanning method. Having the majority of the structure of the hide and the entire surface layer together gives a strength & durability that altered skins simply cannot achieve.

[TwinOaks]

This whole thing appears to be an attempt to gain some validity in an obviously biased point of view. The real downside to marketing like this is that while the OP *might* reach a broader market audience, their bias and lack of real research will completely turn off anyone who bothers to do their own research. For example: Me. I don't make everything I use, so that means I buy a decent amount of it. Given the misinformation in this article, I'd go out of my way to avoid the seller who uses that intro.
Then the defensive statement questioning Nstar - "....could it be that you possibly are a little skewed towards chrome tan for a various reasons?" gives me reason to think that the OP doesn't want to or can't defend their statements.

There are multiple types of leather in the world, and they've been developed for a reason. There is no ONE BEST LEATHER. Period. There are 'best leathers' for a particular use, and loudly proclaiming otherwise is akin to arguing that there's a way to polish the clean end of a turd.

[Sarden]

Wow, the tone here is getting unexpectedly aggresive.

As stated previously we did in fact spend considerable time researching this article, and while the final piece is admittedly a little biased towards vegetable tanning as we prefer natural products ourselves, the article is based on what we deduced from 30 articles was the general consensus.

As we have openly stated our own bias, our reasons for leaning towards vegetable tanning, as well as consider this a common preference among leather aficionados, I don't think it is entirely inappropriate to question if others could be a little biased too. Especially when they are working with chrome leathers themselves.

I'd hardly call the article "misinformation" and I don't think "Ambassador" puts forward any arguments to support such a claim. Most of what we write are facts repeated by numerous sources and I have referred to a few of these in a couple of my replies above. "Ambassador" on the other hand is accusing me of being unable to defend anything, being defensive and only spending considerable time here in order to "gain some validity" — whatever that means.

I came here to get some help and comments from people who know more than I. I thankfully got some that were more useful than the rather odd accusations in the most recent post.

If Ambassador wants to share some of the insights he has obtained through his own research, I would be very glad to hear more and am ready to update our article with these insights in mind.