Wood Coatings Terminology Guide


The Wood Coatings Terminology Guide is designed as an introduction to common terms used in the industry.

12/04/2011 08:20:38
The Wood Coatings Terminology Guide is designed as an introduction to common terms used in the industry.

Hopefully the guide will give you a better understanding of terms used in relation to the Wood Finish industry as in some cases meanings can be slightly different to other coating industries.

As always HMG Paints recommend speaking to our highly trained and qualified representatives if you require more information. Our reps will be more than happy to help with any queries or questions you may have.

Acid Catalysed Lacquer
A two component (2K) lacquer system that is cured by the use of an acid catalyst solution prior to application. Also known as an AC.

Acid Catalyst
The acid catalyst component used to cure an AC lacquer.

The term used to describe the hazy film or whitening produced when the weak acid in either an AC or PC reacts with the Stearate used as a sanding aid in certain sanding sealers.

Bodying Up
Filling up of the grain in French Polishing or building up the coating with polish in a
multi-coat cycle.

A technique of polishing used to increase the gloss level on 2 pack lacquers.

Cold Colour
Reference to a colour or shade that is towards the green end of the colour scale. The opposite to red or ‘warm’.

Fracturing of the coating, primarily as a result of excessive veneer or substrate movement.

A network of fine cracks as opposed to lateral fractures with or against the grain, typically caused by poor application practices such as application of hard lacquers over soft lacquers, the use of the wrong thinner or too much thinner and too short drying times prior to re-application.

The action of slightly ‘flatting’ or sanding between coats of lacquer to aid inter-coat adhesion and to remove any slight imperfections in the film.

Dulling Down
Term used to describe the action of reducing the sheen or gloss of a lacquered finish.

Wood filler or grain filler, usually supplied as a paste, which is used to ‘choke up’ or fill minor holes in the timber or the grain.

The Furniture Industry Research Association, which provides information, advice and independent testing on all activities associated with furniture.

FIRA (BS) 6250
A performance testing procedure for coatings to determine resistance to physical damage and chemical attack.

FIRA 5000
A specific ‘standard’ accredited by FIRA to finishes or systems that meet certain performance criteria which replicate the conditions found in bathrooms and rooms where high water/moisture content prevail.

Fish Eyes
A crater-shaped defect found in the finished film caused by external contamination. Typical sources of the contamination include silicone or wax from other stripping or finishing processes, silicone from aerosol sprays, grease, oil or dirt, and moisture contamination from air lines.

Flash Point
The lowest temperature at which a mixture of vapour in air can be ignited by a naked flame.

Term used to describe the visual or measured ‘sheen’ of a lacquer or finish. Typically rated as gloss (80-90%), Satin (45-65%), Semi-Matt (20-40%), Matt (10-20%) and Dead Matt (0-5%). The level of sheen is measured by a gloss meter which calculates the amount of light reflected from the film surface at 60°.

Natural indentations found in the surface of the timber. Timbers can be ‘tight’ or ‘close’ grained such as Cherry, or ‘open’ grained such as Oak.

A Quality Management System in accordance with ISO 9001:2000 to provide a set of processes that ensure consistency and improvement of working practices. Which in turn provide products and services that meet customer’s requirements.

Medium Density Fibreboard.

Non-Convertible Coatings
Term used to describe a coating that undergoes a chemical or physical change during drying and curing that cannot be reversed after it has occurred i.e. the coating cannot be returned to its liquid state. Typical examples are AC and UV lacquers. Also known as Non-Reversible coatings.

Orange Peel
A film defect which resembles the ‘speckled’ or ‘mottled’ surface of an orange, typically caused by uneven drying, incorrect coating weights or wrong spray application pressures.

The action of sanding a timber substrate after the stripping process to ensure that all remnants of stripper or other contaminants or surface blemishes are fully removed prior to recoating.

Name given to a stain or ‘stipple’ used to give an antique or aged effect on furniture or coated panels, especially picture frames.

Pot life
Associated with two-pack lacquers such as AC or PU, and is a measure of how long after mixing the two components i.e. lacquer and catalyst/hardener, the coating will remain fluid enough to be used.

Pre-catalysed Lacquer
Also known as Precat lacquer. A type of single component (1K) lacquer where an acid catalyst is already incorporated into the formulation with no need for further mixing prior to application.

Abbreviation for Polyurethane lacquers, typically supplied as a two-component system comprising lacquer and Isocyanate hardener.

Reversible Coatings
The term used to describe finishes or coatings which always remain re-soluble in their own solvents i.e. coatings which do not undergo a chemical or physical reaction during drying or curing that cannot be reversed. Also known as Convertible Coatings. A typical examples is Nitrocellulose.

Abbreviation for Ready for Use, meaning the lacquer or paint is supplied in a form that can be used without the need for any additional thinners or catalyst.

A reference to the length of time after manufacture that a product can still be used without any problems assuming it has been stored in its original unopened container in good conditions.

Delamination of the coating due to tangentially-cut veneers moving, or the inconsistent lifting of ‘annual rings’ in timber.

Specific Gravity
Also known as SG or Density – measures the weight per litre of a liquid compared to the same volume of water. Used in the testing of lacquers and when calculating the application coverage of a paint or lacquer.

Stopping Up
The application of wood filler to fill cracks and holes in the timber. The filler is normally applied and sanded smooth prior to any staining or finishing process.

The term used to describe the chemical removal of dried paint or lacquer films prior to refinishing or restoring.

Another term for the timber or material surface that will be worked on or coated.

The measure of a liquids resistance to flow. In lay mans terms this means the ‘thickness’ of the lacquer or paint – for example grease is viscous or ‘thick’ whilst water is non-viscous or ‘thinner’.

Volatile Organic Compound.

Refers to a colour towards the red or ‘warm’ end of the colour spectrum as opposed to green or ‘cold’.

Wet and Dry
Associated with the use of a water when sanding or de-nibbing.as Cherry, or ‘open’ grained such as Oak.

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