A process for coating a surface of a clock mechanism or a device integrated into a watch product with a molecular functionalisation layer, characterised in that it comprises at least the following steps: a) optionally preparing said surface by washing in a solvent and/or in an aqueous detergent, then drying, b) placing said surface in contact with a composition containing an effective quantity of phosphonic compounds until self-assembly of said phosphonic compounds to a fine layer on said surface, c) placing said surface in contact with a composition containing an effective quantity of amine compounds until self-assembly of said amine compounds to a fine layer on said surface, d) removing the supernatant, e) rinsing the functionalised surface, f) drying the functionalised surface, wherein said phosphonic compounds and said amine compounds are different compounds and wherein: either said amine compound is a perfluorinated amine of the following formula ( I'-N): in which n is an integer in the range of between 1 and 100, m is an integer in the range of between 0 and 100 and x is an integer in the range of between 0 and 10, and said phosphonic compound is a perfluorinated phosphonic compound of the following formula ( I'-P): in which n is an integer in the range of between 1 and 100, m is an integer in the range of between 0 and 100 and x is an integer in the range of between 0 and 10; or said amine compound is a linear alkyl amine of the following formula ( I"-N): in which n is an integer in the range of between 1 and 100, preferably between 5 and 30, and even more preferred between 8 and 20; and said phosphonic compound is a perfluorinated phosphonic compound of the following formulae ( I"-P) and ( I"'-P): in which n is an integer in the range of between 1 and 100, preferably between 5 and 30 and even more preferred between 8 and 20. a) optionally preparing said surface by washing in a solvent and/or in an aqueous detergent, then drying, b) placing said surface in contact with a composition containing an effective quantity of phosphonic compounds until self-assembly of said phosphonic compounds to a fine layer on said surface, c) placing said surface in contact with a composition containing an effective quantity of amine compounds until self-assembly of said amine compounds to a fine layer on said surface, d) removing the supernatant, e) rinsing the functionalised surface, f) drying the functionalised surface, either said amine compound is a perfluorinated amine of the following formula ( I'-N): in which n is an integer in the range of between 1 and 100, m is an integer in the range of between 0 and 100 and x is an integer in the range of between 0 and 10, and said phosphonic compound is a perfluorinated phosphonic compound of the following formula ( I'-P): in which n is an integer in the range of between 1 and 100, m is an integer in the range of between 0 and 100 and x is an integer in the range of between 0 and 10; in which n is an integer in the range of between 1 and 100, m is an integer in the range of between 0 and 100 and x is an integer in the range of between 0 and 10, and said phosphonic compound is a perfluorinated phosphonic compound of the following formula ( I'-P): in which n is an integer in the range of between 1 and 100, m is an integer in the range of between 0 and 100 and x is an integer in the range of between 0 and 10; or said amine compound is a linear alkyl amine of the following formula ( I"-N): in which n is an integer in the range of between 1 and 100, preferably between 5 and 30, and even more preferred between 8 and 20; and said phosphonic compound is a perfluorinated phosphonic compound of the following formulae ( I"-P) and ( I"'-P): in which n is an integer in the range of between 1 and 100, preferably between 5 and 30 and even more preferred between 8 and 20. in which n is an integer in the range of between 1 and 100, preferably between 5 and 30, and even more preferred between 8 and 20; and said phosphonic compound is a perfluorinated phosphonic compound of the following formulae ( I"-P) and ( I"'-P): in which n is an integer in the range of between 1 and 100, preferably between 5 and 30 and even more preferred between 8 and 20.