Blog >> Vegetable Tanning vs Chrome Tanning
Our topic of
discussion for this week is vegetable tanning versus Chrome tanning. The
tanning method is an essential step for leather manufacturing; it stabilizes
the collagen structure in the skin and triggers the leather property to
resurface from the skin. The vegetable and chrome tanning are still two widely
used processes for leather manufacturing. However, the number remains little
for vegetable tanning as people derive greater benefits from chrome tanning.
Vegetable tanning
has been a great part of human history. The ancient tanning process can be
traced back as far as approximately 6,000 BCE near ancient civilization of
Indus Valley. Vegetable tanning, unlike
chrome tanning, uses natural resources for its tannin (tanning agent). Plant
parts from
trees like Chestnut wood (Castanea sativa), Quebracho wood
(Schinopsis lorentzii), Tara pods
(Caesalpinia spinosa), Catechu (Acacia Catechu), Chinese gallnut (Rhustyphina semialata), Turkish gallnut
(Quercus infectoria), Gambier (Uncaria gambir), Mimosa or
Wattle bark (Acacia meamsii), Myrobalan (Terminalia chebula), Oak wood (Quercus sp), Sumac (Rhustyphina coriaria) and Valonia Oak (Quercus macrolepis) are used to produce vegetable tannin.
By using natural ingredients, vegetable tanning is
considered to be less hostile to the environment and gives more natural look to
the finished goods; furthermore, the look will gradually improve with time,
giving out a unique patina (a soft sheen that develops on the surface of
leather) for its users. Although vegetable tanning creates an everlasting
leather, the leather is biodegradable and will disintegrate by itself if proper
maintenance is stopped. From the economic perspective, vegetable leather can be
sold at higher price than chrome leather; this makes vegetable leather is more
valuable than its counterpart.
Despite its positive advantages, vegetable tanning has
a lot of drawbacks. It is considered to be inefficient and difficult as the
time requires to complete the whole process can reach up to 2 months; moreover,
skilled craftsmanship is also inevitable as special knowledge is required in
vegetable tanning. Vegetable tanned leather is also susceptible to heat;
exposing it to intense heat will cause the leather to shrink and develop cracks
on its surface. The appearance of vegetable leather is also greatly affected by
the presence of iron as stain marks will appear when they are in contact. In
addition, the cost for doing vegetable tanning is very high because of the
large amount of water it requires in its process.
Figure 2.
Summary Vegetable vs Chrome Tanned Leather
Chrome tanning unlike his counterpart, is more
favoured to be used as a tannin; 90% of the world's tannery right now use
chromium for their tanning. This element serves as a strong oxidizing agent and can
greatly hasten the tanning process. Commonly used in the form of Chromium
Sulphate (Cr2(SO4)3) this green powder will
penetrate the collagen easily and alter the protein structure inside the skin.
Before the discovery of chrome tanning, vegetable
tanning was heavily depended on by tanners to do the tanning process. However,
the slow production process was unable to cope with the high demand, majority
of tanneries decided to drop the old method and replaced it with the new chrome
tanning. Chrome tanning has revolutionized the tanning process by greatly
reducing the processing time. With the help of Chromium tanning, tanners now
can finish the entire production in just within one day. Another great benefit
from chrome tanning is its simplicity, meaning that now everyone can become a tanner with the
help of Chromium sulphate. Based on economic perspective, chrome tanning is
more economical than vegetable tanning since the costs needed to do chrome
tanning is less than vegetable tanning. The leather produced from chrome
tanning is also softer and thinner and can be dyed into various colours.
The downside for chrome tanned leather can be felt by
our environment. Toxic chemicals such as Chromium Sulfate, might increase the
COD level in lakes or rivers in the form of Chromium (VI); Furthermore,
Chromium (VI) may cause respiratory disease such as lung cancer when it is
inhaled; when it is ingested it may cause diseases such as gastrointestinal
disorder and hemorrhagic diathesis. Moreover chrome tanning uses various
chemicals that might cause a detrimental effect if its' released to the
environment. Moreover, The appearance of chrome tanned leather is less natural
compared to vegetable tanned leather and it is not biodegradable.
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