A solution of resin or resinous substance dissolved in alcohol, turpentine or spirit is called ______.
Defining Surface Coatings
Surface coatings are applied to materials to protect them and enhance their appearance. They are classified based on their composition and function. The key difference often lies in whether the coating is transparent or opaque (contains pigments) and the type of liquid carrier (solvent) used.
📝 Detailed Analysis of the Options
(a) varnish
Composition: A varnish is a clear, transparent solution made by dissolving a resin (like shellac, copal, or polyurethane) in a suitable solvent. The solvent can be oil (like linseed oil), alcohol (spirit), or turpentine.
Function: When applied, the solvent evaporates, leaving behind a hard, durable, and transparent film of resin. This protects the surface while allowing the natural grain and color of the material (usually wood) to be visible. The description in the question perfectly matches the definition of a varnish.
(b) distemper
Composition: Distemper is a type of water-based paint. Its main ingredients are a base (usually chalk or whiting), pigments (for color), water (as the solvent), and a binder (traditionally animal glue or casein).
Function: It is an opaque, breathable, and inexpensive coating used for interior walls and ceilings. It is fundamentally different from varnish because it is water-based and contains pigments, making it opaque, not transparent.
(c) aluminium paint
Composition: This is a type of paint, not a varnish. It consists of fine aluminium powder (as the pigment/base) suspended in a vehicle, which can be an oil varnish or a spirit varnish.
Function: It creates a silvery, opaque, and highly protective layer that is resistant to heat and moisture. Because it contains solid aluminium particles, it is not a clear solution like a true varnish.
(d) resin paint
Composition: This is a very general term. All modern paints contain some form of resin, which acts as the binder (vehicle). For example, alkyd paints use alkyd resins, and acrylic paints use acrylic resins.
Function: While technically correct that it's a paint containing resin, "varnish" is the specific and precise term for a *clear solution* of resin in a solvent, as described in the question. "Resin paint" is too broad and usually implies an opaque, pigmented coating.
📊 Comparison of Coatings
| Coating Type | Key Components | Appearance | Primary Solvent |
|---|---|---|---|
| Varnish | Resin + Solvent | Transparent / Clear | Oil, Alcohol, Turpentine |
| Distemper | Pigment + Chalk + Glue + Water | Opaque / Matt | Water |
| Paint (General) | Pigment + Base + Vehicle + Solvent | Opaque | Varies (Water, Oil, etc.) |