Classification of Finishes

In many cases two or more terms may available for the same finish when classification accounting to finishing techniques, finishing materials and finishing effects.

1. Classification according to the finishing technique:

a. Glaze finish: Performed by means off a glazing machine and non-thermoplastic binders. These are used for high quality leathers because it accentuates (more prominent) the natural grain marking particularly well. However, plate finishing is additionally used to seal the finish.

b. plate finish: This is called so because different type of plating machines are used to produce high gloss and smooth films.

c. Glaze/plate: This is  a combination finish consisting of glazing after the base coat and plate finishing as top coat. It's used for leathers with a sensitive grain so as to avoid overloading with polymer binders and also to enhance handle 

properties.

d. Corrected grain finish: This is used for leathers which receive gain impregnation by buffing after grain correction and in most cases  covering polymer finish.

e. Embossed finish; This is used for leathers which receive an artificial or fancy grain by embossing.

f. Spray finish: The name means to finishes which are applied largely by spraying.

g. Curtain coating finish: These finishes are applied by means off the overflow or slot-type curtain coater. Mostly used for leathers which need a highly covering  top coat such a s corrected grain leathers splits.

h. Roll coating finish: In this type of finishing the coat is applied to  obtain effect finishes by means of screen rolls or engraved pattern rolls. 

Read more: General introduction of Finishing and structure of  finishing

2. Classification according to finishing effect:

a. Aniline finish: Transparent coats without pigments except, if needed, very light leveling with aniline coloring materials (spray staining, the depth of penetration regulated by addition of organic solvent or penetrators ). Natural appearance of the grain ought to stay visible.

b. Semi-aniline: Small amounts of covering pigments in the base coat but not in the transparent top coat ere some des can be used. It is a finish between an aniline and an opaque finish.

c. Opaque finish: Includes all type of finish which contain covering pigments and binders, It is the most commonly used finishing  method.

d. Easy-care finish: Particularly resistance to oil, grease and soiling, wet  and dry rubbing, to solvents  and detergents. It made with cross-linking and hardening binders and polyurethane lacquers, additionally  in combination with nitrocellulose products.

e. Two or multitoned finish: Its applied in two or more finishing floats off different colour. The effects is achieved by  means of oblique  spraying padding or printing.

f. Brush-off  finish: This is  an irregular, streaky two tone effect method. A dark and hard nitrocellulose colour is sprayed onto a leather which has been finished in a pale shade and then finally rubbed off by a felt polishing disk.

g. Antique finish: An elaborate manual method  for achieving irregular  two tone effects. The leathers achieve a high embossed grain and after  the application of  a wax resist  are treated with a second mostly darker graining colour. The recessed parts will then  have a  darker shade  compared to e raised  parts.

h. Fancy finish: These include droplet shaped splatter effects produced by reduction of the compressed air setting during spraying;

Crush grain effects produced by creasing the leathers unevenly and then spraying them  with a high gloss polyurethane lacquer in a box  frame. kerosene effect by rubbing bismuth chloride oxide powder over black patent leather. Mother of pearl  effect produced  by means  of special iridescent  pigments n the dye coat. Gold beetle  effect produced by spraying a lacquer solution coloured with basic  methyl violet which responsible for bronzing of the surface.

i. Invisible finish: A finish  which despite  thee protective layer gives the impression of an unfinished surface. Produced on leathers which have been pretreated by means for a penetrating grain impregnation or light polishing ground coat. The leathers are then lightly sprayed with a polyamide  top coat  which contains nitrocellulose top coat  which contains nitrocellulose  matt  lacquer for  regulation of the gloss effect,

j. Conquete finish: A  leather surface to which a light or  dark base coat has been applied is sprayed with a hard coat of contrasting colour  and embossed afar drying. 

k. Solvent free or solvent poor finish In response to ecological conditions and the regulation on clean air (TA Luft, technical instructions on  Air Quality Control, Germany.) increasing efforts have been undertaken during the last years to obtain equivalent  fastness properties to those of solvent based finishing system by means of water dilutable finishing systems.

The main problems were inadequate  fastness to wet rubbing poorer flow properties, more  difficult drying conditions and the production of different handle properties. In order to obtain good results by means of aqueous finishes including aqueous top coat the leather must have been given a particularly uniform absorbing capacity by corresponding retannig, fattliquoring or partial water repellent treatments.

The following factors should be considered when choosing the finishing and coating systems:

1. Use of pigment preparation which dado not contain excessive  amounts of hydrophilic dispersing agents.
2. Use of softer acrylic  and polyurethane dispersions in the base coat and pigment coat and use of harder top coat formulations.
3. Application off thicker coats than in the  case off solvent base finishes in order improve the fastness properties by a good flow out.

l. Film transfer finish: This finishing method is not performed by the application of finishing floats but by means of transfer films. The transfer films are manufactured in specialized factories by lamination of different coloured aluminum bonzes aa high temperatures. They are made in unicolor or with various patterns. The best known products are gold and sliver leather, These leathers were formerly produced with real gold-leaf and sliver foils. Colorless or dyes PVC foils are also sealed onto the surface in order to achieve hi gloss effects. A variant of the film transfer  finish is coating with two component  polyurethane mixtures on a coating machine either by a direct o reversing process.

3. Classification according to the main finishing materials used:

a. Casein finish: Treatment with  non-thermoplastic casein products and pigments or organic dye is mainly used for glaze/plate finishes.

b. Polymer or binder finish: This is the most commonly used type  of finishing leather production and its mainly applied as a plate finish. The production used are thermoplastic binders on the basis of polyacrylates butadiene or vinylidene  chloride copolymers. The film forming  properties of these products are adjusted to produce a wide range of effects from softy/stretchy to hard /inelastic. Depending on thee degree of polymerization.

c. Nitrocellulose  or collodion finish: The film forming  materials nitrated cellulose cotton dissolved in organic solvents also called collodion cotton. Its applied to binder base  coats in a pigmented or transparent thin layer.  

d. Cellulose ester finish free from introgroups: The film forming elements are used its cellulose acetobutyrate dissolved in organic solvents. Compared to collodion the main facility of  these films made in their resistance to yellowing on exposure to light and  heat.

e. Polyurethane finish: Use of highly polymerized addition compounds on the basis  of polyether or polyester  polyols. These are binders dissolved in organic solvents as reactive/non-reactive merchandise and spread in  water in cross linking  or non-crosslinking form.

f. Patent finish: The traditional, very  labor intensive method was a treatment with boiled linseed oil called warm lacquer process. Aa mostly transparent thick  polyurethane lacquer coat is applied to a pigmented polymer binder  bade coat. A high lustre ( aa gentle  sheen or soft glow) finish  is produced.