Difference between revisions of "Vegetable-tanned leather"

Latest revision as of 07:27, 4 July 2023

What is vegetable tanned leather?

Vegetable tanning refers to leather that is tanned with oak bark, spruce bark, quebracho, tara pods, olive leaves, rhubarb roots, mimosa or coffee bean shells in the pit or in the tanning drum. The tanning agent is then a vegetable tanning agent. Also the term "natural leather" is used.

Tanning with plant substances has existed for over 5,000 years and was, for many centuries, the main tanning method. Ornaments placed on stone coffins reveal that vegetable tanning was around in the 4th millennium BC in Egypt. Since the discovery of Ötzi in the ice of the Alps it is evident that several leather types were prepared for various uses even 5,000 years ago. There is no exact account of where exactly vegetable tanning originated, as it was developed independently in different cultures. Various ancient civilizations such as the Egyptians, Greeks, Romans and Indians are believed to have developed vegetable tanning techniques.

Recently, the more modern and industrialised tanning methods have become common and it can be assumed that nowadays only 10 - 12% of all leather is vegetable-tanned. The cost and quality advantages of chrome-tanned leather have reduced the proportion of vegetable-tanned leather to a niche. Before chrome tanning, tanning with vegetable tanning agents was the dominant tanning method. In the niche where vegetable tanned leather is superior to other tanning methods, or where leather lovers prefer this natural tanning agent, vegetable tanned leather is strong and will continue to have its place.

A campaign by the Italian leather industry for vegetable tanned leather (www.pellealvegetale.it).

Vegetable-tanned leather is usually recognized by the brown colouration. Since plant tanning dominated long before chrome tanning, in particular old leather is mostly vegetable-tanned. Today only thick and firm leather is vegetable-tanned. For high-quality shoes, e.g. for the leather soles. Due to their excellent shape retention, vegetable-tanned leather can be moulded, carved and embossed very well. Leather can consist of up to 45% tanning agents. In particular, vegetable tanning agents are better absorbed by leather and therefore fill it better, are therefore heavier and can be better processed into firm leather.

Vegetable tanning is based on tannins (polyphenols and gallic acid) which are found naturally in plant species. Plants store these as a defence mechanism to ward off attacks from potential predators whose digestion is adversely affected upon consumption. Tannins are found in varying concentrations in different plants. In addition to the plants mentioned above, tannins are also contained in wine, chestnuts, hops, sumac and black and green tea. In food, tannins are perceived as dry, rough and furry. The taste of red wine is fundamentally influenced by the type of tannins and their concentration. Many plants used for leather tanning require up to 30 years growth, to allow sufficient amounts of tannins to be produced. Other plants contain more tannins when they are younger. There are around 300 different plant species worldwide, which can be used for tanning.

Oak is suitable for all leather. Oak and spruce bark from younger trees are used, because they contain more tannin.
Chestnut gives a hard and reddish leather.
Mimosa bark and Acacia make leather rather pliable and supple.
Valonea is a Mediterranean, wild species of oak, which grows mainly in Turkey and in Greece. Dried Valonea acorn cups (also called Trillo) have a high tannin content, between 32% and 45%. Valonea is used to make soft and tough leather. Valonea-tanned leather has higher colour-fastness ratings in comparison to other vegetable-tanned leather.
Bark from the flat topped yate or swamp yate (eucalyptus occidentalis) has an extremely high tannin content of 46 - 49%. The tree grows in West Australia and is up to 25 meters high. Since the plant is now rare, the tannin is hardly used.

Vegetable tannins - Quebracho wood

In Middle Ages Europe, forests were cultivated with tannin-rich oak varieties. The tannin-containing bark of the trees was peeled off and brought to mills. These mills were mostly located close to tanneries.

Tannins

Not every plant contains the same percentage of tannin. Tannin is mainly a substance that is released during stressful reactions of the plant (e.g. parasite attack).

Within the same plant, the tannin content varies:

Oak bark contains about 10% tannins (in older trees about 5%) and oak apples up to 70%. The resulting leather is light brown.

Spruce bark has 15% tannins. However, in spruce wood it is a maximum of 1%. Also, this leather is light brown.

Chestnuts can reach 10 percent tannins in wood of old trees. The leather is medium brown and chewy.

Willow bark has 10% tannin and delivers yellowish leather.

The bark of old birch contains 10% tannins. The resulting leather is also yellowish and soft, but resistant.

Valonea has a very high tannin level with 32%. The leather is tough and solid.

Galls or cecidia contains 55–65 % tannic acid. There are over-growths on plants through the eggs of insects. Around the larvae, tannin-containing growths develop. The countries of origin are Hungary, Yugoslavia and Austria.

The dry substance of the vegetable tanning agent extracts delivered to the tannery consists of around 75% tannins, which are absorbed and bound by the hide to be tanned, and 25% non-tanning agents. Over 90% of the tanning agents contained in the tanning agent extract are absorbed by the leather during the tanning process.

Leather tanned with oak with stamp: "pure oak wood - 12 months tanning period".

The tanning process

The vegetable tanning process takes about 20-30 months. Per Skin about 30 kg of bark or 20 kg of fruit or 90 kg oak wood is needed. In 2009, world demand for vegetable tanning raw material was about 130,000 tonnes. The modern tanning with vegetable tanning agents only takes 59 hours compared to a comparable chrome tanning with 54 hours.

The tanning agent is placed together with the hides in water-filled pits, resulting in a bath containing tannic acid after a few days. The skin is regularly exposed to additional baths with higher tannin concentrations.

A special type of pit tanning is the traditional pit tanning. The traditional pit tanning is carried out in particular for sole leather (particularly thick and firm leather), which takes 9 to 18 months. Modern vegetable tanning processes reduce this time to just a few weeks. In combination with tanning in Tanning drum, the process can even be reduced to 4-10 days, whereby the leather does not have exactly the same properties as with pure pit tanning, which produces particularly firm leather with a high tanning agent content. Apart from sole leather, these leathers are also often used for carving, embossing, straps and other specialties because the leather has the best properties for this use.

During tanning, the leather hangs in pits that are filled with the tanning liquor.

Videos about vegetable tanning

Vegetable tanning with oak tannins.

Vegetable tanning in Tuscany, Italy.

Labelling of Leather

Besides the term "vegetable-tanned leather", terms like "natural leather" or "bio leather" are in use, since the tannins are derived from natural raw materials.

Some people react to chromium VI, which is rarely found in leather. Therefore, some people look for chrome-free leather or pure vegetable tanned leather to avoid possible allergies. As tanning methods can be mixed in the leather production, it is important to ask for chrome-free leather (FOC = Free of Chrome) to be sure. The term "vegetable-tanned leather" doesn`t assure this alone. In Europe leather may only be labelled as vegetable tanned without additional information if the total content of the tanning metals (Cr, Al, Ti, Zr, Fe) does not pass 0.3% of the dry weight. If the proportion is higher, the goods must be declared corresponding.

Old vegetable-tanned leather.

The light fastness of vegetable-tanned leather

The dyes in aniline leather or the pigments on finished leather become lighter by light (fading). In the case of uncoloured vegetable-tanned leathers, it behaves differently. The leather darkens by light, moisture and fat.

Vegetable-tanned leather, which was never moistened or oiled or greased, will become darker first, but will become brighter later as a result of drying. Probably this effect is related to fats and oils in the leather. At first, grease moves up to the top of the leather and darkens, but the dryness makes it brighter with time because the fats slowly dry out. But as soon as water or grease gets onto the leather, it darkens strongly.

Vegetable tanned leather day 0, day 16 and day 50 in sunlight.

Tanning methods
Chrome tanning - Vegetable tanning - Synthetic tanning - Tanning with fats and oils

Additional information

Vegetable tannins

WE UNDERSTAND LEATHER - WWW.COLOURLOCK.COM

@@ Line 9: / Line 9: @@
-==Altgegerbtes Leder==
+==What is vegetable tanned leather?==
-'''Altgegerbtes Leder''' oder '''lohgegerbtes Leder''' oder '''lohgares Leder''' oder '''pflanzlich gegerbtes Leder''' oder '''vegetabil gegerbtes Leder''' ist die Bezeichnung für vorwiegend mit '''Eichen-''' und '''Fichtenrinde''', aber auch z. B. '''[[Quebracho|Quebrachoholz]]''', '''[[Tara|Tara-Schoten]]''', '''[[Olivenleder|Olivenblättern]]''', [[Rhabarberleder|Rhabarberwurzeln]] oder '''[[Mimosa|Mimosarinde]]''' in der Grube [[Gerbung|gegerbtes]] Leder. Der [[Gerbstoff]] ist dann immer ein Pflanzengerbstoff.
+Vegetable tanning refers to leather that is [[tanning leather|tanned]] with oak bark, spruce bark, [[quebracho]], [[tara|tara pods]], [[Olive leather|olive leaves]], [[Rhubarb leather|rhubarb roots]], [[mimosa]] or coffee bean shells in the pit or in the [[Tanning leather#Tanning drum|tanning drum]]. The [[Tannins|tanning agent]] is then a vegetable tanning agent. Also the term "[[natural leather]]" is used.
-Die Gerbung mit pflanzlichen Stoffen gibt es seit mehr als 5.000 Jahren und war über viele Jahrhunderte die [[Gerbung|Hauptgerbart]]. Von Verzierungen auf einem Sarkophag weiß man, dass die pflanzliche Gerbung im 4. Jahrtausend vor Christus in Ägypten bekannt war. Durch den Fund von Ötzi im Eis der Alpen weiß man, dass vor ca. 5.000 Jahren verschiedene [[Lederarten]] für verschiedene Verwendungszwecke hergestellt wurden. Man geht davon aus, dass heutzutage nur noch 10 - 12% aller Leder pflanzlich [[Gerbung|gegerbt]] werden.
+Tanning with plant substances has existed for over 5,000 years and was, for many centuries, the main [[tanning leather|tanning method]]. Ornaments placed on stone coffins reveal that vegetable tanning was around in the 4th millennium BC in Egypt. Since the discovery of Ötzi in the ice of the Alps it is evident that several leather types were prepared for various uses even 5,000 years ago. There is no exact account of where exactly vegetable tanning originated, as it was developed independently in different cultures. Various ancient civilizations such as the Egyptians, Greeks, Romans and Indians are believed to have developed vegetable tanning techniques.
-Wirkstoff in der pflanzlichen Gerbung sind die ''Tannine'' als Polyphenole der Gallussäure. Diese werden von den Pflanzen eingelagert, um Fressfeinde fernzuhalten, deren Verdauung durch Tanninaufnahme negativ beeinflußt wird. Tannine finden sich in unterschiedlicher Konzentration in sehr unterschiedlichen Gewächsen; neben den bereits genannten Pflanzen auch in Wein, Kastanien, Hopfen, [[Sumach]], Schwarzem und Grünem Tee. In Lebensmitteln werden Gerbstoffe als trocken, rau und pelzig wahrgenommen; so wird etwa der Geschmack eines Rotweins grundlegend davon mitbestimmt, welche Tannine in welcher Konzentration in ihm enthalten sind. Viele gerbstoffhaltige Pflanzen benötigen bis zu 30 Jahre Wachstum, bis die eine ausreichende Menge Gerbstoff produziert wird.
+Recently, the more modern and [[leather industry|industrialised tanning]] methods have become common and it can be assumed that nowadays only 10 - 12% of all leather is vegetable-tanned. The cost and [[leather quality|quality]] advantages of [[Chrome tanned|chrome-tanned]] leather have reduced the proportion of vegetable-tanned leather to a niche. Before chrome tanning, [[tanning]] with vegetable tanning agents was the dominant tanning method. In the niche where vegetable tanned leather is superior to other [[tanning|tanning methods]], or where leather lovers prefer this natural [[tannins|tanning agent]], vegetable tanned leather is strong and will continue to have its place.
-* '''Eiche''' ist für alle Leder verwendbar. Man verwendet bei Eichen und Fichten die Rinde jüngerer Bäume, weil die mehr Gerbstoff enthalten.
-* '''Kastanie''' macht ein hartes und rötliches Leder.
+<p align=center>
-* '''Mimosarinde''' und '''Akazien''' machen Leder eher biegsam und geschmeidig.
+[[bild:Vegetable-tanned-leather-campaign-italy.jpg|500px]]
-* '''Valonea''' ist eine mediterrane, wildwachsende Eichenart, die vorwiegend in der Türkei und in Griechenland gedeiht. Deren Fruchtbecher mit [[Gerbstoff|gerbstoffreichen]] Schuppen (auch Trillo genannt), hat einen Gerbstoffanteil von 32%. Man kann mit Valonea [[Haptik]] weiches, sowie festes und zähes Leder machen. Mit Valonea gegerbtes Leder ist [[Lichtechtheit|lichtechter]] als andere Pflanzengerbstoffe.
+</p>
+<p align=center>
+''A campaign by the Italian [[leather industry]] for vegetable tanned leather ([https://www.pellealvegetale.it/en/ www.pellealvegetale.it]).''<br></p>
+<p>&nbsp;</p>
+Vegetable-tanned leather is usually recognized by the brown colouration. Since plant tanning dominated long before chrome tanning, in particular old leather is mostly vegetable-tanned. Today only thick and [[Haptic evaluation of leather surfaces#Strength of the leather|firm leather]] is vegetable-tanned. For high-quality [[leather shoes|shoes]], e.g. for the leather soles. Due to their excellent shape retention, vegetable-tanned leather can be [[Formed leather|moulded]], [[Carving leather|carved]] and [[Embossed leather|embossed]] very well. Leather can consist of up to 45% [[Tannins|tanning agents]]. In particular, vegetable tanning agents are better absorbed by leather and therefore [[Haptic evaluation of leather surfaces#Abundance of leather|fill]] it better, are therefore [[Measures and weights|heavier]] and can be better processed into [[Haptic evaluation of leather surfaces#Strength of the leather|firm leather]].
+Vegetable tanning is based on [[tannins]] (polyphenols and gallic acid) which are found naturally in plant species. Plants store these as a defence mechanism to ward off attacks from potential predators whose digestion is adversely affected upon consumption. Tannins are found in varying concentrations in different plants. In addition to the plants mentioned above, tannins are also contained in wine, chestnuts, hops, [[sumac]] and black and green tea. In food, tannins are perceived as dry, rough and furry. The taste of red wine is fundamentally influenced by the type of tannins and their concentration. Many plants used for [[tanning leather|leather tanning]] require up to 30 years growth, to allow sufficient amounts of [[tannins]] to be produced. Other plants contain more tannins when they are younger. There are around 300 different plant species worldwide, which can be used for tanning.
+* '''Oak''' is suitable for all leather. Oak and spruce bark from younger trees are used, because they contain more tannin.
+* '''Chestnut''' gives a hard and reddish leather.
+* '''Mimosa bark''' and '''Acacia ''' make leather rather pliable and supple.
+* '''Valonea''' is a Mediterranean, wild species of oak, which grows mainly in Turkey and in Greece. Dried Valonea acorn cups (also called Trillo) have a high tannin content, between 32% and 45%. Valonea is used to make soft and tough leather. Valonea-tanned leather has higher [[Colour fastness - Light fastness of leather|colour-fastness]] ratings in comparison to other vegetable-tanned leather.
+*  Bark from the '''flat topped yate''' or '''swamp yate''' (eucalyptus occidentalis) has an extremely high tannin content of 46 - 49%. The tree grows in West Australia and is up to 25 meters high. Since the plant is now rare, the tannin is hardly used.
@@ Line 26: / Line 40: @@
 </p>
 <p align=center>
-''Pflanzengerbstoff - [[Quebracho|Quebrachoholz]]''<br></p>
+''Vegetable tannins - [[Quebracho|Quebracho wood]]''<br></p>
 <p>&nbsp;</p>
-Im europäischen Mittelalter wurde insbesondere die Stieleiche für Gerberzwecke in sogenannten '''Lohwäldern''' kultiviert. Die gerbstoffhaltige Rinde der Bäume wurde mit dem sogenannten '''[[Lohlöffel]]''' abgeschält (das mittelhochdeutsche Wort "lo" bezeichnet abreißen, schälen, löchern) und in '''Lohmühlen''' verbracht, wo sie zur schließlichen '''Lohe''' zermahlen wurde. Diese Mühlen befanden sich meist in direkter Nähe von Gerbereien und geben bis heute Straßen und Plätzen in deutschen Städten ihren Namen. In der Kölner Innenstadt etwa erinnern ''Rothgerberbach'', ''Blaubach'' und ''Mühlenbach'' an Lohmühlen, die ihre Rinde über den Rheinauhafen bezogen haben. Ein Teil des Marktviertels nannte sich bereits im 12. Jahrhundert ''Lohmarkt''. Ein anderes Beispiel ist die Lohmühleninsel am Landwehrkanal in Berlin-Kreuzberg, wo seit 1750 Lohe erzeugt worden war. Und auch Familiennamen wie Lohmann, Lohmüller, Löhrer, Loher, Luerer gehen auf dieses Handwerk zurück. Bis heute gibt es rund 300 verschiedene pflanzliche Gerbmöglichkeiten weltweit.
+In Middle Ages Europe, forests were cultivated with tannin-rich oak varieties. The tannin-containing bark of the trees was peeled off and brought to mills. These mills were mostly located close to tanneries.
 ==[[Tannins]]==
-Nicht jede Pflanze ist gleichermaßen gerbstoffhaltig - Tannin ist, wie erwähnt, eigentlich vor allem ein Stoff, der bei Stressreaktionen der Pflanze, etwa bei Parasitenbefall, ausgeschüttet wird. Und auch innerhalb einer bestimmten Pflanze variiert der Gerbstoffgehalt je nach Bestandteil:
+Not every plant contains the same percentage of tannin. Tannin is mainly a substance that is released during stressful reactions of the plant (e.g. parasite attack).
-* Bei der '''Eiche''' befindet sich in der Rinde etwa 10 Prozent Gerbstoff (in älteren Bäumen nur noch 5 Prozent), in Gallen bis zu 70 Prozent. Das entstehende Leder ist hellbraun.
-* '''Fichtenrinde''' weist 15 Prozent Gerbstoff auf, im Fichtenholz sind es allerdings maximal 1 Prozent. Auch hier wird das Leder hellbraun.
+Within the same plant, the tannin content varies:
-* '''Kastanien''' können bei alten Bäumen 10 Prozent Gerbstoff im Holz erreichen; das Leder ist mittelbraun und zäh.
+* '''Oak''' bark contains about 10% tannins (in older trees about 5%) and oak apples up to 70%. The resulting leather is light brown.
-* '''Weidenrinde''' hat 10 Prozent Gerbstoff und liefert gelbliches Leder.
+* '''Spruce bark''' has 15% tannins. However, in spruce wood it is a maximum of 1%. Also, this leather is light brown.
-* Die Rinde alter '''Birken''' enthält 10 Prozent Gerbstoff; das Leder ist ebenfalls gelblich, weich, aber unempfindlich.
+* '''Chestnuts''' can reach 10 percent tannins in wood of old trees. The leather is medium brown and chewy.
-* '''Valonea''' hat mit 32% einen sehr hohen Gerbstoffanteil. Das Leder wird zäh und feste.
+* '''Willow bark''' has 10% tannin and delivers yellowish leather.
-* Der '''Gallapfel''' enthält 55–65 % Gallusgerbsäure und die '''Knopper''' 25–28 % Gerbstoffe. Beides sind Wucherungen an Eichen durch die Eiablage der Gallwespe. Um die Larve entstehen gerbstoffhaltige Wucherungen. Die Ursprungsländer sind Ungarn, Jugoslawien und Österreich.
+* The bark of old '''birch''' contains 10% tannins. The resulting leather is also yellowish and soft, but resistant.
+* '''Valonea''' has a very high tannin level with 32%. The leather is tough and solid.
+* '''Galls or cecidia''' contains 55–65 % tannic acid. There are over-growths on plants through the eggs of insects. Around the larvae, tannin-containing growths develop. The countries of origin are Hungary, Yugoslavia and Austria.
+The dry substance of the vegetable tanning agent extracts delivered to the tannery consists of around 75% [[tannins]], which are absorbed and bound by the [[Hide - Skin|hide]] to be tanned, and 25% non-tanning agents. Over 90% of the tanning agents contained in the tanning agent extract are absorbed by the leather during the [[leather production|tanning process]].
@@ Line 54: / Line 74: @@
 </p>
 <p align=center>
-''Leather tanned with oak with stamp: "pure oakwood - 12 months tanning period".''<br></p>
+''Leather tanned with oak with stamp: "pure oak wood - 12 months tanning period".''<br></p>
 <p>&nbsp;</p>
-==Der [[Gerbung|Gerbprozess]]==
+==The [[tanning leather|tanning process]]==
-Der Lohgerbprozess benötigt etwa 20-30 Monate. Pro [[Haut]] werden dabei ca. 30 kg Rinde oder 20 kg Früchte oder 90 kg Eichenholz verbraucht. 2009 war der weltweite Bedarf an Vegetabilgerbstoffen bei fast 130.000 Tonnen.
+The vegetable tanning process takes about 20-30 months. Per Skin about 30 kg of bark or 20 kg of fruit or 90 kg oak wood is needed. In 2009, world demand for vegetable tanning raw material was about 130,000 tonnes. The modern tanning with vegetable [[tanning agents]] only takes 59 hours compared to a comparable [[Chrome tanned|chrome tanning]] with 54 hours.
-Die Lohe wird gemeinsam mit den Häuten in eine wassergefüllte Grube gelegt, wodurch nach einigen Tagen ein gerbsäurehaltiges Bad entsteht. Die Haut wird regelmäßig weiteren Bädern mit höheren Gerbstoffkonzentrationen ausgesetzt (der sogenannten '''Farbengang''', da sich die Farbintensität der Gerbbrühe mit stärkerer Konzentration erhöht). Dies ist allerdings nur eine Vorbehandlung; nachdem die Häute diese durchlaufen haben, werden sie zur Weitergerbung in den sogenannten ''Versenk'' deponiert - ein dauerhaftes mit Gerbbrühe gefülltes Depot. Der Versenk wird im Abstand von einigen Wochen gewechselt, um das sogenannte ''Auslaugen'' zu vermeiden - nämlich den Fall, dass die Haut sämtliche Gerbstoffe im Wasser bereits aufgenommen hat und dieses anschließend faulig wird.
+The tanning agent is placed together with the hides in water-filled pits, resulting in a bath containing tannic acid after a few days. The skin is regularly exposed to additional baths with higher tannin concentrations.
-Eine spezielle Art der Grubengerbung ist die sogenannte "Altgrubengerbung". Die Altgrubengerbung wird insbesondere bei [[Lederschuhe#Sohlleder oder Sohlenleder|Sohlenledern]] durchgeführt, welche 9 bis 18 Monate dauert.
+A special type of pit tanning is the traditional pit tanning. The traditional pit tanning is carried out in particular for [[Leather shoes#Main leather terms for shoes|sole leather]] (particularly [[Thickness of leather|thick]] and [[Haptic evaluation of leather surfaces#Strength of the leather|firm]] leather), which takes 9 to 18 months. Modern vegetable tanning processes reduce this time to just a few weeks. In combination with tanning in [[Tanning drum]], the process can even be reduced to 4-10 days, whereby the leather does not have exactly the same properties as with pure pit tanning, which produces particularly [[Haptic evaluation of leather surfaces#Strength of the leather|firm]] leather with a high [[Tannins|tanning agent]] content. Apart from [[Leather shoes#Main leather terms for shoes|sole leather]], these leathers are also often used for [[Carving leather|carving]], [[Embossed leather|embossing]], [[Leather belt|straps]] and other specialties because the leather has the [[leather quality|best properties]] for this use.
 <p align=center>
-[[bild:Grubengerbung-02.jpg|250px]]
+[[bild:Grubengerbung-02.jpg|500px]]
-[[bild:Grubengerbung-03.jpg|250px]]
+</p>
+<p align=center>
+[[bild:Grubengerbung-03.jpg|500px]]
 </p>
 <p align=center>
@@ Line 73: / Line 95: @@
 <p>&nbsp;</p>
-Bereits verwendete und ausgelaugte Lohe eignet sich in gepreßter Form ('''Lohkäse''') anschließend noch als Brennmaterial oder auch als Dünger.
+== [[Leather videos|Videos]] about vegetable tanning ==
+<p align=center>
+<flashow>//www.youtube.com/v/leS8jgYGzAQ&fs=1&color1=0x660000&color2=0x550000&border=1|width=500|height=281,25</flashow> </p>
+<p align=center>
+''Vegetable tanning with oak [[tannins]].''
+</p>
-== [[Ledervideos|Film]] über die Gerbung mit [[Gerbstoff]] der Eiche ==
 <p align=center>
-<flashow>http://www.youtube.com/v/XyCaonpEd70&fs=1&color1=0x660000&color2=0x550000&border=1|width=500|height=281,25</flashow> <br></p>
+<flashow>//www.youtube.com/v/dpu9Wq6goWc&fs=1&color1=0x660000&color2=0x550000&border=1|width=500|height=281,25</flashow> </p>
 <p align=center>
-''Die Pflanzliche Gerbung mit [[Gerbstoff|Gerbstoffen]] der Eiche.''
+''Vegetable tanning in Tuscany, Italy.''
 </p>
-==[[Lederkennzeichnung]]==
+==[[Genuine leather|Labelling of Leather]]==
-Weitere Bezeichnungen für Altgerbung bzw. Lohgerbung sind '''Grubengerbung''', '''vegetabile Gerbung''' und '''Pflanzengerbung'''. Häufig werden auch die Begriffe '''"Naturleder"''' oder '''"[[Bio-Leder]]"''' verwendet, da die Gerbstoffe aus natürlichen Rohstoffen stammen.
+Besides the term "vegetable-tanned leather", terms like "natural leather" or "[[bio leather]]" are in use, since the [[tannins]] are derived from natural raw materials.
-Manche Menschen reagieren auf das selten in Leder vorkommende [[Chrom-VI]] und suchen zur Vermeidung von möglichen Allergien [[Chromgerbung#FOC = Free of Chrome|chromfreies]] Leder, bzw. rein pflanzlich gegerbtes Leder. Weil die pflanzliche Gerbung mit der [[Chromgerbung]] gemischt werden kann, reicht nicht die Nachfrage nach "pflanzlich gegerbtem Leder", sondern man muss nach [[Chromgerbung#FOC = Free of Chrome|chromfreiem Leder (FOC = Free of Chrome)]] fragen, um ganz sicher zu gehen.
+Some people react to [[Chrome VI - Chromium VI|chromium VI]], which is rarely found in leather. Therefore, some people look for [[Chrome tanned#Chrome-free leather - FOC = Free of Chrome|chrome-free]] leather or pure vegetable tanned leather to avoid possible allergies. As tanning methods can be mixed in the leather production, it is important to ask for [[Chrome tanned#Chrome-free leather - FOC = Free of Chrome|chrome-free leather (FOC = Free of Chrome)]] to be sure. The term "vegetable-tanned leather" doesn`t assure this alone. In Europe leather may only be labelled as vegetable tanned without additional information if the total content of the tanning metals (Cr, Al, Ti, Zr, Fe) does not pass 0.3% of the dry weight. If the proportion is higher, the goods must be declared corresponding.
-Pflanzlich gegerbte Leder erkennt man meist an der braunen Durchfärbung. Da die Pflanzengerbung lange vor der [[Chromgerbung]] dominierte, sind insbesondere [[Antikleder|alte Leder]] häufig pflanzlich gegerbt. Heute werden insbesondere dicke und feste Leder noch pflanzlich gegerbt. Bei hochwertigen [[Lederschuhe|Schuhen]] z.B. für die [[Lederschuhe#Sohlleder oder Sohlenleder|Ledersohlen]].
 <p align=center>
-[[bild:Stuhl-Antik-013.jpg|250px]]
+[[bild:Stuhl-Antik-013.jpg|500px]]
-[[bild:Arztkoffer-03.jpg|250px]]
 </p>
 <p align=center>
-[[bild:Lederkoffer-04.jpg|250px]]
+[[bild:Arztkoffer-03.jpg|500px]]
-[[bild:Lederball-alt-001.jpg|250px]]
 </p>
 <p align=center>
-[[bild:Westernsattel-02.jpg|250px]]
+[[bild:Lederkoffer-04.jpg|500px]]
-[[bild:Sattel-Motorrad-01.jpg|250px]]
 </p>
 <p align=center>
-''Pictures of vegetable tanned leathers.''<br></p>
+[[bild:Lederball-alt-001.jpg|500px]]
+</p>
+<p align=center>
+[[bild:Westernsattel-02.jpg|500px]]
+</p>
+<p align=center>
+[[bild:Sattel-Motorrad-01.jpg|500px]]
+</p>
+<p align=center>
+''Old vegetable-tanned leather.''<br></p>
 <p>&nbsp;</p>
-==Die [[Lichtechtheit]] von pflanzlich gegerbten Ledern==
+==The [[Colour fastness - Light fastness of leather|light fastness]] of vegetable-tanned leather==
-Die [[Lederfarbe|Farbstoffe]] im [[Anilinleder]] oder die [[Lederfarbe|Pigmente]] auf dem [[Zurichtung|zugerichteten]] Leder werden [[Lichtechtheit|durch Licht heller]]. Bei ungefärbten, pflanzlich gegerbten Ledern verhält es sich andersherum. Das Leder dunkelt durch Licht, Feuchtigkeit und Fettung nach.
+The [[leather colour|dyes]] in [[aniline leather]] or the [[finish|pigments on finished]] leather become [[Colour fastness - Light fastness of leather|lighter by light]] (fading). In the case of uncoloured vegetable-tanned leathers, it behaves differently. The leather darkens by light, moisture and fat.
-Pflanzlich gegerbtes Leder, welches nie feucht wird und nie geölt oder gefettet wird, wird zwar zuerst dunkler, aber durch das Austrocknen mit der Zeit wieder [[Lichtechtheit|heller]]. Vermutlich hängt dieser Effekt mit der [[Fetten|Fettung]] im Leder zusammen. Zuerst steigen Fette aus dem Leder auf und dunkeln es, aber durch die Trockenheit wird es mit der Zeit wieder heller, weil die Fette langsam wegtrocknen. Sobald aber Wasser oder Fett auf das Leder kommt, dunkelt es stark nach.
+Vegetable-tanned leather, which was never moistened or oiled or greased, will become darker first, but will become brighter later as a result of drying. Probably this effect is related to [[Oils & fats in the leather industry|fats and oils]] in the leather. At first, grease moves up to the top of the leather and darkens, but the dryness makes it brighter with time because the fats slowly dry out. But as soon as water or grease gets onto the leather, it darkens strongly.
@@ Line 123: / Line 153: @@
 ''Vegetable tanned leather day 0, day 16 and day 50 in sunlight.''<br></p>
 <p>&nbsp;</p>
-<werbebanner />
 <center>
@@ Line 137: / Line 164: @@
 == Additional information ==
+* [[Leather production]]
 * [[Chrome tanned#Chrome-free leather - FOC = Free of Chrome|Chrome-free leather - FOC = Free of Chrome]]
 * [[Bio leather]]
+* [[Natural leather]]
 * [[Leather production]]
+* [[Leather chemistry]]
 * [[Tannins]]
 * [[Chrome tanned|Chrome tanning]]

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