Primer
From www.leather-dictionary.com - The Leather Dictionary
In the tannery, primers are used as an adhesion promoter between the open-pored aniline leather and the colour layers to be applied. The primer prevents the pigment colour from being "absorbed" by the leather and ensures the adhesion of the pigment colour layer to the leather by its adhesive effect. If too much colour would be absorbed by the leather, the leather would get stiffer and plastic-like caused by the stiffer binders in the leather colour. Due to pre-priming, the colour runs more evenly on the leather because too open-pore areas are "filled" beforehand.
Structure of the leather colouring and finish.
Additional information
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