1. 7. Paint Industrial Products (Testing)

2. basic function of a paint protecting a surface from the action of light, water, and air achieved by the application of a thin resistant impervious, flexible film to the surface usually contains components to hide and decorate the surface liquid components are known as the vehicle solid as the pigment these components are essential for the paint additives to improve various performance aspects may be solid or liquid

4. Component functions Vehicle provide a means for the paint to get onto the brush/roller/spray head provide adhesion of the paint film to the substrate hold the pigment together protect the painted surface Pigment provide hiding power, stain resistance and colour control the gloss of the film decrease moisture penetration improve weather resistance help control corrosion and mildew of the surface Additives improve useability improve drying characteristics reduce breakdown by light, chemical or biological attack

5. Solvent fluidity of paint allows easy application and penetration even into the most intricate crevices the binder is dissolved into a solvent oil-based paints, where the solvent is a hydrocarbon mixture or by colloidal suspension of both pigment and binder in a diluent where the “solvent” is water

6. Binder/resin polymer materials which bind together the pigment particles and hold them onto the surface also be referred to as "film formers“ Water-based paints/acrylics an emulsion which contains tiny spheres of acrylic polymer held in suspension water evaporates spheres are forced together fuse together to form a continuous film of polymer Oil-based paints contain complex monomers polymerise on exposure to the air and on evaporation of the solvent

7. Pigment Primary usually the intensely white powder, TiO 2 provides the main hiding power of the pigment Filler/extender do not provide colour improve various performance characteristics Colourant gives any non-white colour to the paint sometimes inorganic (more common in older paints) more often these days, a mixture of organic dyes.

8. Additives not essential enhance the performance provide a new characteristic include: thickener wetting agent plasticiser antimould agent antifungal agent catalyst flame retardant

9. Physical testing more important than chemical testing density viscosity fineness of grind coverage colour durability

10. Density mass in a known volume hydrometer a production test to relate the mass added to the can to the volume that it is supposed to be the filling mechanism works on mass (usual case) the can says four litres the density needs to be known also a simple check that all the major ingredients are present

11. Non-volatile content simple test for checking that the formulation has the right amount of ingredients evaporate the solvent from a known amount of paint

12. Viscosity measure of flowability of paint can’t be too thick or thin a single viscosity measurement is not sufficient for analysis viscosity profile involving a series of measurements is required specialist devices to measure viscosity-related performance: levelling or flow out resistance to sagging brushability most common standard device is Brookfield viscometer employs a stirring blade which is rotated in the paint force required to turn the spindle is related to the viscosity

13. Coverage (hiding power) defined as the property of a paint that enables it to obliterate beyond recognition any background over which it may be spread the volume of paint required to cover a certain area with a machine-cont Pigment particle size “large” particles may protrude through the surface and detract from the gloss an optimum size below which hiding power decreases. measured by microscopy and light scattering photometers Sieving is generally not suitable because the particle sizes are too low

14. Colour reflectance visible absorption spectrum - paint is not transparent tristimulus value - related to the proportions of the three primary colours needs to match a particular colour Durability designed to measure the effect of sunlight, moisture and temperature on surface coatings applied to a variety of substrates.

15. Chemical testing can’t put through a GC or HPLC directly need to separate components solvent – GC binder – IR pigment – ICP, XRF, IR, UV/VIS Exercise 7.1 Separate oil-based paint into three fractions solvent – distillation dilute paint in organic solvent centrifuge to separate solid pigment dry remaining solution to produce polymerised binder