Paint and Varnishes (Engineering Material)

For polytechnic students

1. SANJIVANI K. B. P. POLYTECHNIC, KOPARGAON With NBA ACCREDIATED programs , Approved by AICTE, New Delhi, Recognized by Govt. of Maharashtra , Affiliated to Maharashtra State Board of Technical Education, Mumbai, ISO 9001:2015 Certified Institute Department:- Computer Technology Class:- First Year Name of Subject:- Basic Chemistry MSBTE Subject Code:- 311305

2. Paint And Varnishes Sanjivani K.B.P. Polytechnic, Kopargaon Department of Computer Technology Mrs. Bhattad K.S.

3. Paint Definition- Mechanical dispersion mixture of one or more pigments in a vehicle. Purposes- 1. Protection Decoration/Beautification Resistance Sanjivani K.B.P. Polytechnic, Kopargaon Department of Computer Technology Mrs. Bhattad K.S.

4. Characteristics of good paint Wear ability Covering ability, Opaque Ease of cleaning Protection of the substrate Environmentally Friendly Aesthetic Practical and Cost Effective Sanjivani K.B.P. Polytechnic, Kopargaon Department of Computer Technology Mrs. Bhattad K.S.

5. Ingredients/Constituent of Paints Pigments - Red pigments- red lead, Sanguine, Caput Mortuum , Indian  Red , Venetian  Red , Oxide  Red , Red   Ochre, anhydrous Fe 2 O 3 chromium oxide, carbon black, brown amber, ferric oxide , cobalt blue , lithopone – provide opacity & color 2. Medium or drying oil/vehicle- linseed oil, Tung oil, dehydrated castor oil-Film Forming Material 3. Thinner- spirits, kerosene, benzene, turpentine, dipentine, Toluene 4. Drier- heavy metallic soap- Oxygen carrier catalyst- accelerate drying by oxidation, polymerization & evaporation 5. Extenders - barytes, gypsum, talc, chalk, silica, clay etc. 6. Plasticizers - Provide elasticity, avoid cracking of film- Triphenyl Phosphate, Tricresyl Phosphate, diamyl phthalate, tributyl phthalate & dibutyl tartarate Sanjivani K.B.P. Polytechnic, Kopargaon Department of Computer Technology Mrs. Bhattad K.S.

6. Varnish Natural or synthetic resin in oil or in thinner or in both. Varnishes-Gives transparent, glossy, lustrous, durable film. Types Oil varnish [Oleo resinous Varnish]- copal varnish Dries by evaporation, followed by oxidation & polymerization . Spirit varnish- Shellac varnish Dries very rapidly by evaporation . Sanjivani K.B.P. Polytechnic, Kopargaon Department of Computer Technology Mrs. Bhattad K.S.

7. DIFFERENCE BETWEEN PAINTS AND VARNISHES Paint Varnish Paints have a long range of colors Varnish has little or no color they may or may not be transparent It is transparent have added pigments and binders It has no added pigment They can be applied on any surface. Varnishes are applied over wood stains or painted surface. Paints are also used to give texture to a surface and they may or may not be glossy. Film formed is glossy, translucent and protective. Paint hide surface on which they are applied. It Provide only glossy & transparent film. Sanjivani K.B.P. Polytechnic, Kopargaon Department of Computer Technology Mrs. Bhattad K.S.