To earn the right to be described as leather, a durable, rot-proof product, skins undergo a number of stages of transformation through leather finishing techniques drawing on the skills and know-how of tanners.
After the preservation, sorting and wet work phases, the skin is put through the tanning process which renders it rot-proof.
What is leather finishing?
To reach the finished leather stage, a series of treatments is applied to these tanned leathers, then the skins are dyed and fatted, in order to guarantee softness and suppleness. Currying is a process that dries the skins and makes them softer so that they are more resistant to use. At the end of this stage, it is also possible to modify the natural grain of the leather. Drumming for example, works by shrinking the grain and creates more or less pronounced aesthetic effects.
The finish is the last stage in producing a useable leather. This phase includes all the chemical, manual and mechanical ennobling techniques that seek to give leathers their finished appearance, conferring upon it aesthetic, sensorial and protective characteristics. Grained, varnished, embossed, perforated, stretch…the palette of finishes is vast and constantly expanding thanks to recipes and innovations concocted by tanners.
It is by focusing on innovations that are both aesthetic and eco-responsible, developed by the leather exhibitors at Première Vision, that we are going to examine the crucial “finishing” stage.
Mechanical leather finishing
Smooth, grained, shiny or lacquered: these leather textures and many more are the result of mechanical operations. Very specific machines and tools are used by expert operators: spray guns, pneumatics, roll coaters, presses, but also knives and stones, combining to produce the desired end result.
It should be noted that these days, workshops use machines that consume less energy and operate using green electricity. These techniques also have the advantage of not requiring harmful chemical inputs. This is particularly true of embossing and perforation, two techniques that we will now describe in more detail.
Embossing is a technique that uses heat to produce a raised design on the skin thanks to the application of a hot press onto the leather. Among textured leathers, we can mention the mechanical grains such as Saffiano or the patterns recreating the patterns of exotic skins, such as crocodile or lizardskin. Embossing has the advantage of offering a vast creative choice, including exclusive designs invented by the tanner or the designer.
Other mechanical techniques are etching and scarification of skins. The sculpture is produced through the use of blades that split the leather to create relief and draw 3D patterns in the material. For example, it is possible to imitate the very specific design of raised python scales.
Splitting can be used to produce a variety of patterns carved in 3D in the material, creating effects rather like the gills of mushrooms. Produced using a marking machine, etching on skins creates stamping and milling effects from original designs. The scope is absolutely infinite. Fitting into an upcycling approach, these techniques also have a significant eco-responsible potential. That is because these finishes can embellish skins that originally presented defects and were destined to be discarded.
A perforated leather is characterised by a pattern created using cutters in round, square or triangular shapes. The distances between the cut-outs can be more or less regular and is decided according to a pre-established design. It can be used to create logos, or a decorative, floral or geometric pattern. The designs are entirely customisable and unlimited in scope. It is even possible to create a lacy pattern in leather. Particularly widespread in the automobile sector, perforated leather is also found in the clothing and leather goods sectors for decorative reasons.
Finishes are defined by the application of finishing products to the surface of skins. They can be protective, fashion-inspired or can combine the two. There are plenty of options and the range is continually diversifying. In contrast to mechanical techniques, these finishes use chemical substances to achieve their objectives. So, a sprayed pigmented finish will produce a uniform and covering colour. Innovations are increasingly focused on eco-responsibility and there is growing interest in eco-finishes with reduced chemical impact.
The “eco-finish with a reduced chemical impact” performance code developed by Première Vision, refers to treatments, dyes, prints and finishes that ensure a reduction in the use of chemical products and guarantee their harmlessness for people and the environment. Ultimately, this means finishes using aqueous solutions that limit VOC emissions, coatings with a bio-polymer base and formulas free of heavy metals and glutaraldehyde.
Efforts are also concentrated around minimising consumption of these adhesives in order to ensure more reasoned waste management. In order to showcase the natural features of the skin, translucence has been popular in recent collections. Waxy finishes, produced using beeswax, or hand finishes such as stamping, add a discrete and shimmer and patina to skins.
To offer even greater sustainability, some leathers become biodegradable when recycled under appropriate conditions.
Applying a foil or a transfer to the surface of the skin allows it to preserve all its properties. The leather is covered with a film through the use of a machine with a cylinder. The thickness of this film is extremely precise, and in the range of micrometres. This printing technique means the skin can be decorated using a digital image. Depending on the technique used, these films give the skins patterns, texture, and very varied appearances – printed, metallic, iridescent, pearly, cracked – which can also be layered on each other onto the leather to offer a very creative combination of decorations.
The lamination technique means heat bonding the leather to another material to give it specific mechanical, performance or aesthetic properties. Materials are assembled using adhesives, often with water-based formulae, concocted by tanners according to the type of materials. They are placed in the machine and pressed by a cylinder at a given temperature.
A reversible leather is one that has been bonded to another leather. This offers stylistic possibilities by playing with contrasting colours, matt and shine to offer customised products. This leather is ideal for use in leather goods or clothing. Another option is to bond a leather with a textile. Leather associated with organza or silk gives a couture effect. This technique is the basis of stretch leather. A very finely split lamb leather is bonded to an elastic textile. This technique preserves the technical and aesthetic performances of the leather and gives it the effect of being a highly sensual second skin.
For a sportier or hybrid use, the combination of a high-performance technical tissue, like neoprene, and a hand-finished leather can give ultra-personalised results, in line with current creative demands.