Post 582 by Gautam Shah


These are few links on Wood and Wood Finishing processes and materials. Categories covered are:







Sawn Timber > Wikipedia image by Kotivalo


WOOD RESOURCES Blog Post 217 Dt 14 Oct 2014

SOFTWOODS and HARDWOODS Blog Post 513 Dt 8 Sept 2015

WOOD COMPOSITES Blog Post 378 Dt 28 March 2015

ROSEWOOD Blog Post 376 Dt 26 March 2015

SOME VARIETIES of WOODS of Indian subcontinent Post 126 Dt 12 July 2015

WOOD-BASED PRODUCTS Blog Post 177 Dt 7 Sept 2014


Finishing a kokeshi in Japan >Wikipedia image by Fg2


WOOD SURFACE FINISHING Blog Post 472 Dt 13 July 2015

WOOD FINISHES Blog Post 306 Dt 15 Jan 2015

WOOD FINISHES- Dt 22 July 2014



SURFACE LEVELLING Blog Post 291 Dt 31 Dec 2014

WHAT ONE CAN DO TO A MATERIAL ? Blog Post 334 Dt 12 Jan 2015

JOINTS in SURFACE FINISHES Blog Post 469 Dt 9 July 2015


Japanese Lacquer ware in the Ostasiatiska museet, Stockholm, Sweden >Wikipedia image by Daderot



CLEAR COATINGS Blog Post 182 Dt 12 Sept 2014

CLEAR COATINGS- Post 119 Dt 4 March 2015

SHELLAC or LAC COATINGS Dt 26 April 2014

UNDERSTANDING LACQUERS Blog Post 498 Dt 16 Aug 2015

LACQUERS or NC LACQUERS Blog Post Dt 27 April 2014

VARNISH Dt 25 April 2014

COATINGS as thin Surfacing Blog Post 482 Dt 25 July 2015

CLEAR versus PIGMENTED COATINGS Blog Post 553 Dt 29 Nov 2015

PRIMER COATINGS Blog Post 442 Dt 7 June 2015

APPLICATION of COATINGS Blog Post 300 Dt 9 Jan 2015

COATINGS -surface finishing technologies Blog Post 238 Dt 8 Nov 2014

FILM FORMING PROCESS in COATINGS Blog Post 173 Dt 3 Sept 2014

SINGLE or MULTI-COAT SYSTEMS Blog Post 437 Dt 30 May 2015

METAL COATINGS Blog Post 438 Dt 1 June 2015

GILDING Blog Post 471 Dt 13 July 2015


Exterior Maple Wood deck staining Flickr image by Olger Fallas


SOLVENTS and THINNERS for coatings Blog Post 320 Dt 29 Jan 2015

PAINT THINNERS – 1 Blog Post 416 Dt 8 May 2015

PAINT THINNERS – Part 2 Blog Post 423 Dt 30 March 2015

SOLVENTS for THINNERS Blog Post 492 Dt 9 Aug 2015


Wood chips composite board > Wikipedia image by C. Sander and durch Urheber


FILLERS and COMPOSITES Blog Post 169 Dt 30 Aug 2014

COMPOSITES – Part 1 Blog Post 156 Dt 17 Aug 2014


MATRIX of COMPOSITES Blog Post 168 Dt 29 Aug 2014


Glue laminated Large span wood beam at Richmond Olympic Oval, > Wikipedia image by Thelastminute (Duncan Rawlinson)



Post 306 –by Gautam Shah




Woods are fashioned to a variety of finishes such as bark stripped, chopped, rough hewn, sawn, planned, sanded, etc. Timbers gain variety of finishes due to planned seasoning, ageing and exposures. Such finishes are valued for certain uses and so re-formed on fresh timbers, or old surfaces are restored-altered for specific effects.Timbers offer surface quality that is end of the grains, and faces towards and away from the core.


Finishes for wood depend on several factors.

Primarily a wood finish depends on its proposed use as a product or composite. The product defines its sensorial and engineering properties. The product also determines, the technology used for sizing and then finishing. The wood for a product is checked, if it is sap inclusive or heart exclusive, type of wood – soft or hard, type of cut – quarter, rift, tangential or slab, etc.

Wood Router

Quality of wood (jungle -often called firewood, commercial or special timbers, etc.) and form of the product requires very specific method and material of applique finishing. The applied finishes are affected by the nature of wood (soft or hard), level of moisture content, direction grain, presence of gum-resins (aliphatic compounds, waxy and resinous substances), and colour. Overt finishes must take care of grain filling, colour correction (by staining-bleaching), and rectification of anatomical anomalies such as straight or cross grain, knots, shakes, pith, etc.


Wood sizing, product shaping and finishing, all are affected by the atmospheric conditions (temperature, moisture, wind, dust). Wood finishing technology is product dependent, which in turn is considered in terms of its economic viability. The time and effort involved in finishing a wood product must match its economic, aesthetic and functional requirements. A low quality wood, a low-cost product, or an engineering-structural item whose sensorial qualities are less relevant must receive appropriate treatment.



Wood products where feel or texture also necessitates visually appealing finish. This process starts with selection wood, grain pattern and its orientation, finishing technique and the coating. In case of restoration and conservation of wood structures and other utilitarian items, one must check the age of wood, decaying agents, presence of moisture, surface contaminants like dust, soot, oil-grease, residues of earlier finishes, burns and marks of singeing, sunken grains, etc. Other important cares include tools and techniques used for surface correction must not physically scrape the surface, chemically affect the surface or leave a residual product. Care is also required that all processes must be reversible (in future if it is realized that this are damaging).

Wood conservation-preservation




Postby Gautam Shah



Lacquer is a very generic term applied to a variety of coating systems. It indicates a surfacing system, where a film forming substance has been dissolved in or diluted with a solvent. On application the solvent evaporates leaving a thin film on the surface.


Lac or Shellac is a type of resin, produced by insects thriving on the cell sap of certain host plants. It is produced in Eastern parts of India and the SE Asia. The natural resin, as extracted contains internal and external impurities. These are removed mechanically, by melting and filtration processes. Two main forms are commercially available, Button and prills or flakes. Other custom products include coloured sticks for colouring and moulding craft items.
Wax is a natural constituent of Lac forming 2.5 to 5%. Lac Wax was often used, in Floor-polishes and cosmetics, later replaced by Carnauba wax. Lac Dyes were used for silk and wool, than Lac as a resin, in early 19th C before the availability of Synthetic Dyes.


Lac or shellac is bio-degradable, eco-friendly, tasteless and non-toxic material. So ideal for children toys, play-cards, book cover coatings, etc. It is highly inflammable, softens with and so can be moulded. Moulded lacquer is used for making bangles and jewellery embellishments. The moulding process involves heating, combining with additives, colours, kneading, hammering and shaping into a mass like dough.


The lacquer, on evaporation of its solvents changes the phase from Liquid to Solid, but does not convert itself into different substance. Lacquer films are soluble in the (original) solvent. Lacquers are also thermoplastic (will soften with an increase in heat) materials. The film forming substances of lacquers are linear polymers high in polymer weight with good solvent releasing property. Such substances are often very hard and brittle, so require addition of plasticizers to achieve better adhesion, flexibility and durability of the gloss.


Commercially the term Lacquer is applied to Solvent-based Coating systems (against water-based systems) that offer hard, glossy and durable film. In this sense, there are Two basic varieties:

1 Thermoplastics type: Nitro cellulose, Acrylics, Chlorinated Rubber, Vinyls, Epoxy.

2 Thermosetting type: Acrylics, Epoxy Resins, Polyurethanes, Vinyls, Alkyd, Melamine.


Cellulosic Polymers

Cellulose is the most widely occurring, a natural polymer, available in almost all plants. Primary sources of industrial cellulose are cotton fibres and wood. Cellulose is a polyhydric-alcohol, and forms esters with organic acids. It also forms reaction products with inorganic acids. These cellulosic derivatives used in production of various types of lacquers are classified as:

1. esters of inorganic acids -nitro cellulose

2. esters of organic acids -cellulose acetate

3. others -methyl and ethyl cellulose


Lacquers can be classified into two basic groups:

NC Lacquers and Acrylic or Plastic Lacquers.

Lamellar Lines Mudguard Horizontal Lacquered Sheet

Nitro Cellulose Lacquers

NC Lacquers consist of Nitro cellulose as the main raw material to which a variety of plasticizer and resins are added, to provide wide range of film properties. PLASTICIZERS increase elasticity and extensibility of the film. Commonly used Plasticizers are, blown-castor oil, dibutyl phthalate, dioctyl phthalate, dibutyl sebacate, butyl stearate, chlorinated diphenyls. Additions of RESINS increase gloss and adhesion of the film. The resins are coconut and castor oil alkyds, maleic modified ester gum, cyclohexanone (ketonic) resins, acrylic resins, toluene sulfonamides formaldehyde resins.


NC Lacquers are produced by dissolving or diluting lacquer and suitable plasticizers in a mix of solvents. The SOLVENTS act in three ways: Active solvents are (ethyl acetate, butyl acetate), Latent solvents (ethyl alcohol, butyl alcohol, diacetone alcohol), and Diluents (toluene, xylene). A suitable mix of these basic three types of solvents is known as `Thinner‘. A very specific quality of Thinner is required for each application and weather condition.

NC Lacquers do not become yellow with ageing. It has no peeling problem. Lacquers provide very ‘water-white’ (no colouration or tinge) film. NC Lacquers are re-coatable and removable substances.

NC Lacquers are used on wood, metals, metals like gold, silver and copper, plastics, leather, paper, fabrics, as hair-fixers, and Nail-polishes. Lacquer is one of the best surface sealing material for wood products and so forms the primer coat for melamine, etc. 


Solvent-based nitrocellulose lacquers (from resin of nitration of cotton (lint) and other cellulose based materials, were used commercially from the 19th C. These lacquers began to replace shellac lacquer and were used as protective or rust inhibitive clear coatings for brass musical instruments, gift items and furniture. These were also used in white-goods products (refrigerators, irons, cooking tops, etc. and in automobiles. These lasted for several decades till arrival of ‘Polymer based lacquers‘.

These materials are called Lacquers because the film is ‘water-white’. Acrylic lacquers of thermoplastic type are characterized by a transparent water white film, very good resistance to decolouration from temperature and UV light, good electrical properties, outdoor durability, excellent resistance to mineral oil-greases, resistance to chemical fumes, resistance to water based alkaline substances.


Acrylic lacquers convertible coating that is on drying covert to a different product, which is non-dissoluble and non-removable. These are used for: wood items, clear coating for brass, copper, and aluminium, as a top coat for final gloss and protection air-crafts, automobiles, toys, auto-parts, industrial components, consumer durables, TV cabinets. These are used as clear-invisible coating for exposed surfaces like bricks, stones and concrete. Acrylic lacquers with soluble dyes form transparent glass coatings. One of the major uses is for internal coatings of food and beverage cans.

Thermosetting Acrylics provide a hard and scratch proof coating, good colour retention, better water and detergent resistance, better gloss and chalking resistance.