Difference between revisions of "Finish"
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==Problems with deficient finish== | ==Problems with deficient finish== | ||
| − | + | The finish of a pigmented leather can vary. However, it usually consists of a [[primer]], a color coat and the top coat. Usually, these layers are additionally stabilized with a [[crosslinker]]. In case of faulty procedures, this can lead to various problems. | |
| − | * | + | * If the application area is provided with a type of release agent (fats, oils, silicones, etc.), [[Colour separation of leather|colour separation]] may occur over time. |
| − | * | + | * The finish consists of several layers. If the waiting time between the steps is too long, it can affect the adhesion. The separation is then not complete, but between individual layers. The cause may be release agents, which are used to prevent adhesive bonds between layered hides. The sooner the next finish layer is applied, the better the binding is. |
| − | * | + | * If the applied finish is too soft, it is [[leather damages|wear-sensitive]]. Scratches and abrasions can occur. In particular, moisture and fats can enhance such effects. Since a leather should ideally be soft and warm, the tanner must find the best solution. |
| − | * | + | * If the applied top coat is too thin, the clour rubbs off. |
| − | * | + | * If the layers are applied too thick, the leather becomes very [[Haptic evaluation of leather surfaces|plastic-like and feels unnatural and cold]]. |
| − | * | + | * If the [[crosslinker]] is missing, the finishing is susceptible to [[leather damages|wear]]. |
| − | * | + | * If the finish is too hard, this can lead to cracking. When the leather is bent, there are microbreaks which make the leather appear greyish. Usually in the depths of the [[Leather grain - Grain side|grain]]. |
| − | * | + | * Too soft or unstable binders can lead to stickiness of the surface. [[Patent leather]] tends to stickiness when getting older. But also sun can intensify this effect with sensitive leathers. |
| − | * | + | * If a leather is very [[Gloss of leather|dull]], it can appear greyish. |
| − | * | + | * If the pigments are UV-sensitive, the leather [[Colour fastness - Light fastness of leather|fades]]. |
| − | * | + | * Sensitive binders and other chemicals used in finishing can turn yellowish. |
| − | * | + | * Contamination in the colour or on the leather during paint application or during drying may be visible when dry. |
| − | * | + | * A too thick colour layer on leathers which tend to [[looseness]], reinforces this effect. |
| − | * [[ | + | * [[leather colour|Aniline dyes]] in the finish can [[Flamingo effect|migrate]] or [[Dye transfer from leather|transfer dye]]. |
| − | * | + | * Amines of upholstery foams or NOx (nitrogen, for example, by exhaust gases from forklift trucks in leather storage) can produce yellowish changes on light finishes. |
Revision as of 22:27, 31 January 2017
Contents
Finish
The finishing of a leather determines the appearance of the final surface of the leather and the surface properties. This includes coloring, waterproofing, wax dressings, but also the mechanical processing steps such as the ironing or embossing of the leather.
Finishing with pigment containing leather colours
To make leather more durable, more stain-resistant and permanently water-repellent, a layer of a binder-pigment-mixture is applied to surface of smooth leather that has already been completely precoloured with aniline dyes. This color coat is also called finish or pigmentation. Motorcycle suits, but also many leisure jackets, shoes, car, furniture and bags made of smooth leather have this protective color layer. These leathers are then referred to as pigmented leather or finished leather.
Smooth leather without such colour layer is called aniline leather. Leather with a very thin finish is called aniline leather, refined or semianiline leather. Smooth leather with a layer thickness of more than 0.15 millimeters in color or foil must be declared as coated leather in Europe.
The advantage of aniline leather is a warm feel and naturalness. Disadvantage is the sensitivity. Pigmented leather feels colder and firmer, but is significantly easier to clean and care and less sensitive. Pigmented leathers also have lower breathability poperties than porous leather.
There are also leather which have an oil coating or wax coating. For these leathers, uncoloured or dyed waxes and / or oils are applied to the leather surface. Such leather is called pull-up leather.
Primer - Finish / Top Coat
A primer is first applied as an adhesion promoter. The top coat, a kind of clear protective coating, is then applied to the subsequent color layer. Top Coats protects the binder color from abrasion and discolouration and determines the degree of gloss and the haptic. Crosslinkers provide improved fastnesses as additives. In case of particularly matt leather, a duller is added to the top coat and / or to the colour. Vehicle leather is often very matt and leather-covered dashboards must be particularly matt because of the risk of reflections in the front screen.
Video about different kinds of smooth leather.
Structure of the leather colouring and finish. Without finish = aniline leather.
A water drop on a pigmented smooth leather runs off. The pores of the leather are closed.
In the leather production, the pigmentation is applied by means of rotating spray guns.
The application of a pigment leather colour by leather repair companies is carried out manually with a spray gun.
Car leather was not dyed throug until the 70s, 80s. With some leathers, this lead to a beautiful patina.
Typical top pigmentation on un-dyed vegetable-tanned leather shimmers brownishly when getting patina.
Depending on the thickness of the applied pigment colouration, the smooth leather is referred to differently. No colour layer: Aniline leather. Little colour, but hair pores still recognizable: Aniline leather, refined or semianilin leather. Much colour and hair pores only little or not recognizable: Pigmented smooth leather.
Pure aniline leather: Pores are completely visible and there is no finish on the leather.
Semi-aniline leather: Pores are clearly visible, but a thin layer of paint is on the leather surface.
Pores are hardly distinguishable. A stronger colour layer is on the leather surface. Only a leather consultant or expert can investigate whether this leather may still be referred to as semi-aniline leather.
Pigmented smooth leather: Pores
are no longer distinguishable. The leather has a thick layer of paint.
Problems with deficient finish
The finish of a pigmented leather can vary. However, it usually consists of a primer, a color coat and the top coat. Usually, these layers are additionally stabilized with a crosslinker. In case of faulty procedures, this can lead to various problems.
- If the application area is provided with a type of release agent (fats, oils, silicones, etc.), colour separation may occur over time.
- The finish consists of several layers. If the waiting time between the steps is too long, it can affect the adhesion. The separation is then not complete, but between individual layers. The cause may be release agents, which are used to prevent adhesive bonds between layered hides. The sooner the next finish layer is applied, the better the binding is.
- If the applied finish is too soft, it is wear-sensitive. Scratches and abrasions can occur. In particular, moisture and fats can enhance such effects. Since a leather should ideally be soft and warm, the tanner must find the best solution.
- If the applied top coat is too thin, the clour rubbs off.
- If the layers are applied too thick, the leather becomes very plastic-like and feels unnatural and cold.
- If the crosslinker is missing, the finishing is susceptible to wear.
- If the finish is too hard, this can lead to cracking. When the leather is bent, there are microbreaks which make the leather appear greyish. Usually in the depths of the grain.
* Too soft or unstable binders can lead to stickiness of the surface. Patent leather tends to stickiness when getting older. But also sun can intensify this effect with sensitive leathers.
- If a leather is very dull, it can appear greyish.
- If the pigments are UV-sensitive, the leather fades.
- Sensitive binders and other chemicals used in finishing can turn yellowish.
- Contamination in the colour or on the leather during paint application or during drying may be visible when dry.
- A too thick colour layer on leathers which tend to looseness, reinforces this effect.
- Aniline dyes in the finish can migrate or transfer dye.
- Amines of upholstery foams or NOx (nitrogen, for example, by exhaust gases from forklift trucks in leather storage) can produce yellowish changes on light finishes.
Additional information
- Crackled leather - Crackle finished leather
- Metallic leather
- Ironing leather
- Glazing leather
- Gloss of leather
- Metamerism
- Micro hollow balls
Videos about the leather production
The leather production in a modern tannery.
Leather videos about the peculiarities of metallic effects on leather.
| Process steps in the leather production |
|---|
| storage - soaking - liming - fleshing - splitting - pickling - tanning - neutralising - withering - sorting - shaving - yeing (through colouring) and fatliquoring - drying - finish - softening - final check |
| Tanning methods |
|---|
| Chrome tanning - Vegetable-tanned leather - Synthetic tanning - Tanning with fats and oils |
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