Quantity of linseed oil slowly added to 100 g of pigment while rubbing with a spatula until reaching a point at which the mixture takes the form of a ball. Oil absorption value, is commonly used for predicting the binder amount for a specified pigment during paint formulation.

Amount of fatty acid added to the polyester backbone of alkyd resin. Oil length is defined as the total weight of oil in 100% solids alkyd resin. If oil length is higher than 60%, “long-oil alkyd resin”, between 40% and 60%, “medium-oil alkyd resin”, lower than 40%,“short-oil alkyd resin” is obtained.

See Polyester resins

Polyester resins

Ester based polymers derived from polycondensation of polyols and polyacids. Although their backbone structure is similar, to point out the difference from the fatty acid containing alkyd resins, they are called oil-free polyesters. If the polyols and polyacids contain unsaturation, polyester resins are called “unsaturated polyester resins”, if not, they are called “saturated polyester resins”

General name of chemicals, which are formed by the reaction of a definite number of monomers but not large enough to be qualified as a polymer. Although, there is no widespread agreement on the definition of oligomer, the molecular weight of an oligomer ranges from a few hundred to a few thousand and an oligomer consists of 2 to 20 repeating units (mers).

A property of matter that prevents light from passing through it or a condition of being non-transparent. If an object consumes all the light coming to it by reflection, scattering, and/or absorbtion, this object is said to be opaque.

Organic coatings that do not fill and close the small pores of the wood. Open-pore coatings, wet the small crevices without filling and closing them either because they are applied at the low film thicknesses or because they wet the crevices very well due to teir relatively low surface tensions which can be achieved with the help of additives.

This surface defect can be characterized by bumps and valleys resembling an orange skin texture of substrate.This orange skin texture is generally due to poor levelling and it is more common in spray and roller applications. If the surface tension differs at various points on the surface, the migration of paint can cause orange peel. It should be borne in mind that, high viscosity is another factor hindering the levelling.

1) General name of coating materials, having a backbone structure of organic polymers, oligomers or monomer based binders. Organic coating material with no pigment is called clear coat or varnish and if pigmented then it’s called paint.
2) Film formed by the film formation of organic coating material. See Also Putty, Powder coatings

Polyester Putty / Knife Putty

Name given to putties that unsaturated polyester resins or epoxy resins are used as binders and that reaches to very high stiffness after spatula application and drying.

Putty

Organic coating material that contains extenders above the Critical Pigment Volume Concentration (CPVC). Putties are used to fill holes, cracks, and eliminate roughness on the substrate. Putties can be applied using spatula and rollers due to their high viscosity.

Powder coatings

Solvent free coatings which use resins with glass transition temperatures higher than room temperature. Powder coatings are comminuted to 20-100 microns. Powders clung to the surface forms a thin film after high temperature baking.

Electrostatic spray applications of powder coatings

Through these applications, powder coating fluidized by mixing with air is sprayed using a powder gun with an orifice. A high voltage of 40-100 kV connected to a negative electrode at the orifice ionizes air molecules. This cloud of ions is called “corona”. Powder particles pick-up anions when passing through the corona and become negatively charged. Since the object to be coated has become anode because of grounding it attracts particles to its surface. Particles are neutralized when they reach the surface. Loose powder coating film, turns to a tough, durable, continuous, film with good adhesion after baking.

Group of pigments synthesized from basic organic molecules and possessing the ability to enhance the aesthetics in paint industry by virtue of their wide range of colors.

Inorganic color pigments

Inorganic based pigments, most of which are formed by metal oxides, metal oxide mixtures and carbon black. Almost all inorganic pigments used today are obtained synthetically.
 

Natural clays with surplus OH groups on their surface, are reacted with ammonium salts  to increase their compatibility with paints. They attribute shear thinning and thixotropy to the paint by forming hydrogen bonds.

Compounds having silane groups with high affinity to polar groups at one end and hydrocarbon part that is highly compatible with the main binder at the other end. Especially, they are used as additives to improve the adhesion of coatings applied on surfaces rich in polar groups like metal, glass and concrete.

Think of two fluids with the same chemical composition but differing in concentration which are separated by a semi-permeable membrane. This membrane permits passage of small size solvent molecules but not the large solute molecules. Movement of solvent molecules from an area of low solute concentration to an area of high solute concentration is called “osmosis”. During osmosis, movement of solvent molecules leads to an increase in mass followed by an increase in pressure. The equilibrium in osmosis is reached when concentration difference (driving force of osmosis) and pressure difference which acts against it balance each other.

During osmosis in a cup divided into two parts by a semi-permeable membrane, liquid mass in the high solvent concentration part increases and exerts a pressure on the membrane. When this pressure is high enough and doesn’t allow any further mass transfer, the movement of solvent molecules stops. This pressure is called osmotic pressure. Paint film acts as a semi-permeable membrane and lets water migrate through itself when a water-soluble impurity exists on the substrate or in its composition. Osmotic pressure in paint films results in a paint defect called “blistering“.

Blistering

Formation of blisters filled with gas or liquid on a dried coating film. Main reasons for liquid filled blisters could be development of local corrosions on the application surface and existence of water soluble salts in wet paint or application surface. In addition, for especially oven dried coatings, factors such as existence of solvents that are unable to pass the thick coating film can cause gas filled blisters. Blistering is a defect that hinders the protective and decorative functions of the coating.
 

Resistance of organic coatings against UV, water, oxygen, chemicals, microorganisms, mold, temperature, temperature differences, wind and abrasives.

Most reliable tests, performed to measure the resistance of organic coatings to external factors, are the ones that are held at natural outdoor environment. These tests are preferrebly carried out at test stations located in places where severe weather conditions prevail (e.g, Florida, USA; Arizona, USA; Okinawa, Japan; North Sea Coast, Europe).

Excess hardening of a high temperature cured coating as a result of curing for a longer time and/or at higher temperatures than required.

See Auxochrome groups

Chemical groups which can be presented in the structure of pigments and dyestuffs and can contribute to color of the compound together with main chromophore groups.
 

Drying oils, drying and semi-drying alkyds polymerize over the unsaturated bonds in the fatty acids with the oxygen in the air. If the drying of the organic coating films occurs through this mechanism, this process is called “oxidative drying”, “auto-oxidative drying” or “drying with oxygen in the air”.
See Also Air drying, Drying oils, Drying alkyd resins, Semi-drying alkyd resins

Air drying

General name for organic coatings that can lead to dry rigid films at ambient conditions without any assistance after application. Coatings that form films by solvent evaporation and oxidative drying are characterized as “air drying”, since they appear to dry with no assistance.

Non-drying oils

General name for oils obtained by reaction of glycerine with fatty acids that do not contain unsaturation or contain limited unsaturation. There is no distinct definition of non-drying oils as in the case of drying oils. However, oils with an average unsaturation value smaller than or equal to one double bond per one fatty acid chain, are practically classified as “non-drying oils”.

Drying oils

Natural vegetable oils that contain unsaturated fatty acids connected to three hydroxyl group of glycerine molecule. Drying oils dry by polymerizing with air oxygen via opening of the double bonds on fatty acids.

Semi-drying oils

General name of oils, formed by reaction of glycerine with fatty acids with limited unsaturation. (Semi-drying oils do not have a certain definition as the drying oils). Practically, it is conveninent to define oils as semi-drying if they have an approximately 1.5 - 2 unsaturation per fatty acid chain.

 

Cylic ether groups pendant to the epoxy resin. Oxirane groups are also called as epoxy group.
Chemical formula: