orative, functional, or both. The coating itself may be an all-over coating, completely coveri ng the substrate, or it may only cover parts of the substrate. An example of all of these types of coating is a product label on man 6y drinks bottles- n 846 one side 46t has an all-oven 846 r functional coating (the adhesive) a nd the other side has one or more decorative coatings in an appropriate pattern (the printing) to form t he words and images. Paints and lacquers aren 846 coatings that mostly have dual uses of protecting the substrate and being decor Functional coatings may be applied to change the surface properties of the substrate, such as adhesion, wetability, corrosion resistance, or wear resistance. In other cases, e.g. semiconductor device fabricat ion (where the substrate is a wafer), t 6he coating adds a completely new property such as a magnetic respon se or electrical conductivity and forms an essential part of 46the finished product. categorized according to the mechanisms for drying or curing. Although drying may refer to evaporation of the s olvent or thinner, it usually refers to oxidative cross-linking of the binders an 46td is indistinguishable from cur ing. Some paints form by solvent evaporation on 846 tly, but most rely on cross-linking proce Paints that dry by solvent evap 46toration and contain the solid binder dissolved in a solvent are known as lacquers. A solid film forms when the solvent evaporates, and because the film can re-dissolve in solvent, lacquers are unsu itable for applicati 46tons where chemical resistance is importan 6t. Classic nitrocellulose lacquers fall into this ca tegory, as do non-grain raising stains composed of dyes dissolved in solvent and more modern acrylic-based coatin A major consideration for most coating processes is that the coating is to be ap 6plied at a controlled thick ness, and a number of different processes are n 846 in use to achieve this control, ranging from a simple brush f or painting a wall, to some very expensive
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