Magic of Paint

  • Introduction

     

    All objects are vulnerable at their surfaces. It is therefore vital  to modify the surface to change the properties of the substrate. 

    Paint is the most versatile coating and can be applied to any substrate, no matter how awkward the shape may be.

    Different surface coatings can be applied – wallpaper, plastic sheeting, chrome and silver plating. 

    Paints or ‘surface coatings’ provide protection, decoration or a specialized function 

    Practical exercises will give a better understanding of the properties of the different ingredients in a paint system.

    Costing of the project impacts directly on system selection. 

     

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  • Function of surface coatings

     

    Protection 
    Decoration 
    Communication 
    Environmental Properties 
    Fixation 
    Modification of Surface Properties

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  • Protection

     

    Paints and lacquers are coatings that mostly have dual uses of protecting the substrate and being decorative, although some artists paints are only for decoration, and the paint on large industrial pipes is presumably only for the function of preventing corrosion.
    Protection of a surface against external environment which may chemically or physically damaging.
    As an example – soft woods used in a joinery for buildings, needs to be protected against moisture and dirt by protecting it with a layer of varnish or paint.
    Functional coatings may be applied to change the surface properties of the substrate, such as adhesion, wettability, corrosion resistance, or wear resistance.

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  • Decoration

     

    Decorating a surface to look attractive.
    There are three aspects:- 
    Colour:- There can be an infinity of variety of shades.
    Opacity:- A major consideration for most coating processes is that the coating is to be applied at a controlled thickness, and a number of different processes are in use to achieve this control, ranging from a simple brush for painting a wall,whereby the paint covers the underneath or hides it, so one cannot see the surface that has been covered.
    Gloss:- That is the shininess of a surface.

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  • Types of Paint

     

    The difference between water based and solvent based paints:
    Water based Paint
    Water based paints are those commonly known  as PVA, emulsions, acrylics or latex paints
    Solvent based Paint
    Solvent based paints are enamels based on alkyd resins

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  • Pigments

     

    Gives the paint colour & opacity

    Titanium Dioxide
    Extender Pigments
    Colour Pigments
    Rust-inhibiting Pigments
    Organic and Inorganic Pigments

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  • Liquids

     

    As a liquid we define the solvent which is the dilettante  in the paint system
    Water based system= Water
    Solvent based system=Solvent
    These thin the pigments/resin mixture so that it can be easily applied with a brush, roller or sprayer and aids penetration

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  • Additives – Affect  and enhance paint properties

     

    Dispersants
    Surfactants
    Biocides
    De-foamers
    Thickness and rheology modifiers -different characteristics such as flow, drying and sag resistance 

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