Varnish, a class of coatings that do not contain coloring substances and that, when applied to a substrate, form a transparent film with protective , decorative or special properties. Varnish used to be called varnish, which is the transliteration of English varnish.
General coatings have corresponding varnish products, such as asphalt varnish, alkyd varnish, nitro varnish, acrylic varnish, epoxy varnish, polyurethane varnish, etc. Even for the same paint, there may be several varnish products with different uses, suitable for different protective occasions.
There are two types of asphalt varnishes: petroleum asphalt and coal tar pitch. Petroleum asphalt varnish is mainly used for the surface of containers and metal machinery as moisture-proof, water-resistant and anti-corrosion. Coal tar pitch varnish, also known as Heishui Luo Song, is made of coal tar pitch dissolved in coal tar solvent. It dries quickly and has good water resistance. It is mainly used for painting ship chains, steel and wooden objects in damp places, and inland waterway ships. Wooden boat bottom etc.
A medium-oil alkyd varnish formulated from linseed oil, suitable for general interior wood and metal surface finishing or coating finishing. Pentaerythritol alkyd resin varnish, can be used for exterior general wood and metal surface finishing or coating finish.
Nitro varnish, with nitrocellulose as a film-forming substance, is used to paint wood and metal surfaces and the surface finish of nitro varnish, adding copper gold powder and aluminum silver powder for color development. The varnish products that are now adjusted and used are called nitro gold-adjusted varnishes.
Acrylic varnish, with good adhesion, varnish made of acrylic resin copolymerized with different acrylic monomers, suitable for different protective purposes. Polymethacrylic resin varnishes are used for protective coatings on steel surfaces after phosphating; acrylic varnishes copolymerized with acrylic acid, methacrylic acid esters and methacrylic acid can be used for anti-corrosion and moisture-proof coatings for electrical appliances, instruments and light industrial products .
Epoxy varnish, good adhesion, good acid and alkali resistance, can be used for primer and overcoat protection of various metal surfaces, as well as concrete primer coating on concrete surfaces.
Polyurethane varnish dries quickly, and the paint film is bright and wear-resistant. The basic point is to distinguish whether the curing agent is an aromatic TDI prepolymer or an aliphatic HDI prepolymer. Aromatic polyurethane varnishes are not suitable for outdoor environments, otherwise they are susceptible to yellowing changes due to ultraviolet rays. Aromatic polyurethane varnish suitable for finishing wood furniture and metal surfaces. Aliphatic polyurethane varnish, usually formulated from light-based acrylic resin and HDI shrinkage, is suitable for surface protection of instruments, meters, transportation vehicles, steel structures and finish coating of colored paints.
