Tawing with alum - Alum tanned
Tawing is a method of tanning with aluminium salts (alum). It is a naturally-occurring double salt, but which is also artificially produced. Tawing comes under mineral tanning and is one of the oldest tanning processes. After tanning with alum, the dried leather is stiff and firm. To make it softer, the leather is then tumbled and greased.
Alum tanning makes the leather white and very water-sensitive. The tannins are washable, making this leather much more sensitive than with chrome tanning which, with a few exceptions such as for Sheepskin, has replaced alum tanning.
Alum tanning: Sheepskin and leather straps.
Alum tanning: Leather belt with braided parchment.
Alum tanning: Cricket ball from England.
Glacé leather
Glacé tanning is a form of traditional white tanning and is based on natural ingredients. These include alum (aluminium sulphate), salt, egg yolk, wheat flour, fats and water. The tanning itself is a very short process, which takes only a few hours.
Glacé leather has traditionally been used as glove leather (usually goatskin).
Nowadays glacé leather is described, when the tanning method is not clear. Leather with "glacé effect" is also offered. In such cases, the tanning method is then deviated. It's generally not clear what is meant by "glacé effect".
Glacé gloves are very sensitive to water due to the non-permanent, washable tanning. The ring finger of this glove was irreparably damaged by moisture.
Alum designer leather jacket from Italy with water stains on the back from 2017. The stains cannot be removed.
Additional information
- Tanning leather
- Tannins
- Mineral tanning
- Chrome tanned
- Vegetable-tanned leather
- Synthetic tanned
- Tanning with fats and oils
- Chamois leather
- Brain tanning
| Tanning methods |
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| Chrome tanning - Vegetable-tanned leather - Synthetic tanning - Tanning with fats and oils |
Certainly! My expertise in leather tanning spans various traditional and modern techniques, including mineral tanning, chrome tanning, vegetable-tanned leather, synthetic tanning, and the use of specific agents like alum, fats, and oils. Let's delve into the concepts mentioned in the article:
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Tawing with Alum: Tawing is a historic method of tanning using aluminum salts (alum). This process falls under mineral tanning, making use of alum, a double salt occurring naturally but also produced artificially. The outcome of tawing with alum renders the leather stiff and firm. However, to enhance its softness, the leather undergoes tumbling and greasing post-tanning.
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Alum Tanning Characteristics: Alum tanning results in leather that is notably white and highly sensitive to water. Compared to chrome tanning, the leather produced through alum tanning is more washable due to the presence of tannins. Despite its historical significance, chrome tanning has largely replaced alum tanning, except for specific uses like Sheepskin.
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Glacé Leather: Glacé tanning is a traditional white tanning process utilizing natural ingredients such as alum (aluminum sulfate), salt, egg yolk, wheat flour, fats, and water. This method is relatively brief, taking only a few hours. Glacé leather, traditionally made from goatskin, has historically been used for gloves. However, contemporary glacé leather offerings often lack clarity regarding the specific tanning method, leading to confusion about the "glacé effect."
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Water Sensitivity: Both alum tanned and glacé leather types are highly sensitive to water. Glacé gloves, due to their non-permanent and washable tanning, are particularly susceptible to water damage, which can result in irreparable harm to the leather, as seen in the article's reference to a damaged ring finger on a glacé glove.
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Alum Tanning in Products: Alum-tanned products, such as leather straps, belts with braided parchment, and even cricket balls from England, showcase the historical application of this tanning method.
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Challenges with Alum-Tanned Leather: An Italian designer leather jacket, alum-tanned, displayed water stains in 2017 that proved impossible to remove, highlighting the susceptibility of alum-tanned leather to water damage.
Tanning methods play a pivotal role in determining leather characteristics, durability, and resistance to environmental factors. The mentioned methods—chrome tanning, vegetable-tanned leather, synthetic tanning, and tanning with fats and oils—showcase diverse approaches to achieve desired leather attributes. Understanding these methods aids in comprehending the distinct qualities and applications of various leather types in different industries and products.
