Wood Coatings

Theory and Practice


  • Franco Bulian, Vice Director, CATAS, Italy
  • Jon Graystone, Principal Research Scientist, Paint Resarch Association (PRA), UK

Wood Coatings addresses the factors responsible for the performance of wood coatings in both domestic and industrial situations. The term 'wood coatings' covers a broad range of products including stains, varnishes, paints and supporting ancillary products that may be used indoors or outdoors. Techniques for coating wood go back many centuries but in recent decades there has been a move towards more environmentally-friendly materials, for example, the use of water-borne rather than solvent-borne chemicals. A major objective of Wood Coatings is to explain the underlying factors that influence selection, application and general operational issues. Basic information on the chemistry and technology of coatings is included for the benefit of students and laboratory technicians. Additionally, the book includes individual chapters of interest to architects, specifiers, and industrial users.
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Students and laboratory technicians to obtain a basic understanding of the chemistry behind wood coatings. Industrial professionals wishing to update their knowledge.


Book information

  • Published: June 2009
  • Imprint: ELSEVIER
  • ISBN: 978-0-444-52840-7

Table of Contents

Chapter 1Markets for wood and wood coatings1. Prologue2. Markets for wood and wood coatings2.1. Consumption of timber2.2. End use sectors – coated wood2.3. Joinery and windows2.4. Furniture2.5. Industrial wood coatings2.6. Parquet and wood flooring2.7. Major players in industrial wood coatings2.8. The decorative 'woodcare' market2.9. Technology breakdown2.10. Environmental legislation2.10.1. Timetable for implementation of the solvents directiveChapter 2Wood and wood-based substrates1. Introduction2. Wood and timber3. Chemical composition3.1. Macromolecular substances3.1.1. Cellulose3.1.2. Hemicellulose3.1.3. Lignin3.2. Low molecular weight substances (Extractives)3.2.1. Aromatic phenol derivates 3.2.2. Aliphatic derivates (Fats and Waxes)3.2.3. Terpenes and terpenoids3.3. Acidity in wood3.4. Minerals in wood4. Morphology4.1. Cellular structures4.1.1. Softwoods (needlewood or coniferous wood)4.1.2. Hardwoods (Broadleaf)4.2. Heartwood and sapwood4.3. Wood anisotropy4.4. The cutting of wood4.5. Wood and water (moisture content)4.6. Seasoning of wood4.7. Dimensional movement of wood4.8. The density of wood5. Biodegradation of wood5.1. Wood as a nutrient5.1.1. Decay and fungal attack5.1.2. Insect attack6. Modified wood6.1. Thermal treatments6.2. Chemical treatments 6.3. Surface treatments7. Wood appearance7.1. Colour8. Utilisation of wood (Timber) in construction and furniture8.1. Solid wood8.2. Wood-based panel products 8.2.1. Solid wood panels8.2.2. Plywood8.2.3. Particleboards8.2.4. Fibreboards8.2.5. Multilaminar wood 9. Covering materials9.1. Decorative veneers9.2. Impregnated papers9.2.1. Melamine impregnated papers9.2.2. Finish impregnated papers9.3. Plastic sheets9.4. Laminates9.4.1. High pressure decorative laminate (HPL)9.4.2. Continuously pressed laminates (CPL) 10. APPENDIX - Some important wood speciesChapter 3Raw materials for wood coatings (1) - Film formers (Binders, Resins and Polymers)1. Introduction2. Chemistry of coatings 2.1. Drying oils and modified drying oils2.1.1. Oil composition2.1.2. Cross linking mechanism2.1.3. Modified oils2.2. Natural resins and modified natural resins2.2.1. Shellac2.2.2. Colophony or Rosin oil2.2.3. Waxes2.3. Cellulosic film formers2.3.1. Cellulose esters: CAB and CAP2.3.2. Cellulose nitrate2.3.3. Cellulose ethers2.4. Alkyds (oil modified polyester resins)2.4.1. Drying alkyds2.4.2. Polyamide modified alkyds2.4.3. Urethane-modified alkyds2.4.4. Styrenated and vinyl alkyds2.4.5. Silicone alkyds2.4.6. Non-drying alkyds2.4.7. High solids alkyds2.5. Isocyanates and polyurethanes2.5.1. Properties of polyurethanes2.5.2. Two-component (or two-pack) polyurethanes(2K)2.6. Amino resins (Urea and Melamine)2.7. Polyester resins2.7.1. Unsaturated polyesters2.8. Acrylic resins2.8.1. Thermoplastic acrylic resins2.8.2. Thermosetting acrylic resins. Polycondensation reaction.2.8.3. Thermosetting acrylic resins. Polyaddition reaction photochemically activated (Radiation Curing)2.9. Vinyl resins2.10. Epoxy resins2.11. Epoxy esters3. Water-borne binders and film-formers3.1. Water soluble alkyds and polyesters3.2. Emulsified alkyds3.3. Water-borne epoxy resins3.4. Water-borne 2-pack isocyanate systems (Urethanes)3.5. Aqueous polyurethane dispersions (PUD’s)3.6. Emulsion polymerisation3.7. Composition of water-borne dispersions3.7.1. Cross linking water-borne dispersions3.7.2. Morphology of polymer particlesChapter 4Raw Materials for wood coatings (2) – Solvents, Additives and Colorants1. Introduction2. Solvents and Diluents2.1. Solvent properties2.1.1. Solvency2.1.2. Viscosity reduction2.1.3. Evaporation rate2.1.4. Surface tension2.1.5. Flammability2.1.6. Electrical conductance and resistance2.1.7. Environmental impact2.1.8. Odour2.1.9. Water as a solvent (carrier or diluent)3. Additives3.1. Additives affecting the properties of liquid coating materials3.1.1. Anti–skinning agents3.1.2. Surface active agents3.1.3. Pigment wetting and dispersing agents3.1.4. Anti-foaming agents3.1.5. Anti-settling agents3.1.6. Rheological modifiers3.1.7. Coalescing agents3.1.8. Biocides3.1.9. Film preservation agents3.1.10. pH regulators and buffers3.2. Additives controlling the drying (conversion) of coating materials3.2.1. Driers (oxidative cross linking)3.2.2. Catalysts3.2.3. Photoinitiators3.3. Additives affecting the properties of the coating film3.3.1. Additives to improve or modify appearance3.3.2. Sanding additives3.3.3. Matting agents3.3.4. Levelling agents3.3.5. UV absorbers3.3.6. Radical scavengers3.3.7. Flame retardants3.3.8. Plasticisers4. Colorants (Pigments and Dyes)4.1. Origin of colorant properties4.2. Required colorant properties4.2.1. Colour4.2.2. Tinctorial strength4.2.3. Physical form4.2.4. Durability4.2.5. Toxicology4.3. Pigment types4.3.1. Inorganic white pigments4.3.2. Coloured inorganic pigments 4.3.3. Coloured organic pigments4.3.4. Extender pigmentsChapter 5Classification and formulation of wood coatings1. Introduction2. Classification2.1. Generic type2.1.1. Paint2.1.2. Clear and semi-transparent coatings (Varnishes and Lacquers)2.1.3. Stains and lasures2.1.4. Oils, polishes and patinas2.2. Functional classifications3. Mixture Properties3.1. Introduction3.2. Pigment to binder ratios3.3. Graphical representation of a coating formulation.3.4. Formulation protocols3.5. Relevance of formulation data to usersChapter 6Properties of wood coatings – Testing and characterisation1. Introduction2. Standards2.1. Standards organisations3. Characterisation of liquid coatings3.1. Compositional aspects3.2. Solid content3.3. Pigment content3.4. Density3.5. Determination of the Volatile Organic Compounds (or content)3.5.1. Photo curing coatings3.5.2. Chemically curing polyesters3.6. Other test methods4. Properties related to application4.1. Viscosity4.2. Pot life 4.3. Minimum film formation temperature4.4. Drying Time5. Applied Coatings (Dry film)5.1. Properties related to appearance5.1.1. Light transmission (transparency and hiding power)5.1.2. Light reflectance (gloss)5.1.3. Light absorption (Colour)6. Coatings Performance6.1. General properties6.1.1. Film thickness6.1.2. Adhesive performance6.1.3. Surface hardness6.1.4. Stackability (Blocking)6.2. Coatings for exterior use6.2.1. Weathering methods6.2.2. Water permeability6.2.3. Resistance against biological deterioration6.3. Coatings for interior use6.3.1. Mechanical stresses6.3.2. Physical stresses6.3.3. Resistance to climatic variations6.3.4. Resistance to light6.3.5. Chemical interactionsChapter 7Market needs and end uses (1) - Architectural (decorative) wood coatings1. Introduction1.1. Summary of key differences1.2. Decorative coatings for exterior wood1.2.1. Exterior wood stains (Lasures)1.2.2. Varnishes and other clear coats1.2.3. Paint and paint systems for wood1.3. Decorative coatings for interior wood1.3.1. General purpose1.3.2. Wood flooring1.4. Durability of exterior wood coatings1.4.1. Design factors1.4.2. Preservation of timber1.4.3. Specification of exterior wood coatings1.4.4. Maintenance of exterior wood coatingsChapter 8Market needs and end uses (2) - Industrial wood coatings1. Introduction2. Industrial finishing of wood joinery2.1. Preservation2.2. Coating systems2.2.2 Typical industrial joinery finishing schedule2.3. Environmental legislation considerations3. Industrial finishing of furniture3.1. Coatings for wood furniture - some functional types3.1.1. Bleaches3.1.2. Sizes and washcoats3.1.3. Stains3.1.4. Fillers3.1.5. Sealers3.1.6. Topcoats3.2. Influence of substrate on coating type3.3. Coatings for wood furniture – Factors influencing technology choice3.3.1. Economic factors and economies of scale3.3.2. Operational factors – Fully assembled or knock-down?3.3.3. Appearance aspects – Open or closed-pore?3.4. Functional needs3.5. Legislation3.5.1. Assembled furniture3.5.2. Knock-down furniture3.6. Coating systems for some typical applications4. Coatings for wood flooring4.1. Formulating parquet and related coatingsChapter 9Operational aspects of wood coatings (1): application and surface preparation.1. Introduction1.1. Quality1.2. Application and spreading rates1.3. Productivity1.4. Cleaning/Product change/Maintenance1.5. Transfer efficiency2. Application systems2.1. Contact methods2.1.1. Brushing2.1.2. Padding2.1.3. Dipping2.1.4. Autoclave vacuum and pressure application2.1.5. Roller coating2.1.6. Curtain coating2.1.7. Flow coating2.1.8. Vacuum coaters2.2. Atomising systems2.2.1. Conventional air atomised systems - Pneumatic atomisation2.2.2. Pneumatic atomisation with high air volume and low pressure (HVLP)2.2.3. Hydraulic atomization (Airless) 2.2.4. Hydraulic air assisted atomization2.2.5. Operational Aspects of Spray application2.2.6. Mechanical atomization 2.2.7. Spray application of powder coatings3. Preparation of the substrate3.1. Sanding of the substrate3.2. Sanding papers3.2.1. Metal-wool 3.3. Brush sanding3.4. BleachingChapter 10Film formation: drying and curing1. Introduction2. Film formation by evaporation of solvent from solution: physical drying2.1. Non-aqueous solutions2.2. High Solids solvent-borne coatings2.3. Water-borne solutions2.4. Water-borne emulsions2.4.1. Water-borne dispersions - Latexes3. Powder coatings4. Film formation and chemical cross-linking4.1. Thermosetting Resins5. Representative curing technologies5.1. One component physically drying coatings - lacquers5.2. One component chemically drying coatings (ambient temperatures).5.3. Multi-pack chemically drying coatings 5.4. Stoving coatings5.5. Photo-curing coating 6. Industrial drying processes6.1.1. Infrared lamps (IR) 6.1.2. Infrared plates6.1.3. Microwave sources6.2. Radiation-curing systems6.3. Electron Beam (EB)7. Industrial plants7.1. Horizontal tunnels7.2. Vertical ovens 7.3. Multi-level ovens7.4. Tunnel ovens for multi-layer racks7.5. Ovens for three-dimensional elements7.6. Drying chambers