Glass Mirror

Introduction

Glass Mirrors are made of good quality plate/sheet glass of different thickness varying from 2 mm to 7 mm. It is coated chemically on one side to give the desired reflection. The need of these mirrors is increasing with the increase of population, hotels, restaurants, Hair dressing saloons, railways, vehicles and other household decorations etc. It is popularly used for looking purpose by one and all.

Market Potential

In view of the utility of mirrors, it is considered an important and essential item without which one cannot imagine modern life. It is roughly estimated that there are around 325 registered units producing mirrors by hand pouring simple machines. These types of units are artisans in nature which are mostly engaged in decoration of glass. The production capacity of all these SSI units put together is estimated approximately at 7.2 million sq. meters per annum.

The demand of these mirrors is increasing day by day due to its use in building construction decoration and export to the neighboring countries. The mirrors are largely consumed by Fancy shops, Jewellary shops, Hotels, Bars, Saloons, Furniture manufacturers, tailoring shops, theatres, show-rooms, household, Railways, Automobiles industry etc. The gap between demand and supply is estimated approximately at 10% in the country. It is an essential item in each and every house. Being fragile it enjoys good replacement market also. There is good demand of the product for export market in the neighbouring countries and far-east countries.

There is a good scope for ancillarisation of the mirror industry to support large industries like Railways, Automobile, Defence. Automobiles can buy semi-finished items from the smallscale sector. Hence there is a good scope to set up glass mirror industry in SSI sector.

Basis and Presumptions

1) The unit will work on a single shift basis for 300 working days in a year.

2) The unit can achieve its full production in the first year itself.

3) Labour and wages are taken as per the prescribed minimum wages of the Govt. rates.

4) Interest calculation is taken @ 13% for both fixed and working capital of total investment.

5) Margin Money is considered @ 10-25% depending upon the locations and scheme adopted by the entrepreneurs.

6) The operative period of the project is around 10 years.

7) The costs of land, construction charges, machinery and equipments, raw materials and consumables, other contingent
expenses are taken as per the prices prevailing in the market at the time of project preparation.

Implementation Schedule

Technical Aspects
Process of Manufacture

Selection of Glass Sheet/Plate

The best quality of mirror is obtained by silvering plate glass which produces true and undisturbed image due to its high polish, flatness and uniform thickness. If sheet glass is used instead, true reflection is not possible because of characteristic surface waviness of the glass even though it is of the highest grade. It is generally used for making small mirrors only. While selecting sheet glass for mirroring, it is particularly important to see that the central portion which would be directly in the line of sight, should be free from defects as far as possible. Depending on the quality of plate or sheet glass used, where defects are accentuated by silvering, various grade of mirrors are produced.

Cleaning of Glass

If the surface of glass has been left exposed to the atmosphere for a long time, it gets hydrolyzed and also coated with film of dust, oil grease and metal salts. In each cases an adherent and uniform layer of silver is formed only after proper cleaning of the glass surface. For this purpose, the surface is treated with an organic solvent like, alcohol, ether and Carbon tetrachloride or with an alkaline solutions such as sodium hydroxide and sodium phosphate, sulphuric acid and nitric acid etc. which make the surface suitable for adherence of silvering.

This cleaning is done by using absorbent cotton of sufficient thickness rapped on a glass spatula or rod soaked with pure HNO3 and distilled water. The entire surface is properly cleaned and rinsed off by using ordinary water followed by distilled water.

Sensitizing the Glass

Sensitizing makes the surface active for attracting the silver metal to form a quick adhering and uniform film. It is done by treating the surface of the glass sheet with stannous chloride solution after properly cleaning the glass.

Stannous chloride performs two functions in the manufacturing of the silver mirrors

(a) It speeds up the precipitation of metallic silver from a silver solution, and

(b) It increases the adherence of silver to glass surface.

Application of sensitizing solution to the glass surfaces can be done by: (i) Pouring, (ii) Spraying with spray gun, (iii) Immersing the surface into sensitizing solution. One minute is sufficient for sensitizing the glass surface.

Protective Coating on Silvered Surface of the Mirror

The durability and life of silver coating is backed by protective backing paint. The finished mirror is fit to withstand, atmospheric corrosion of the silver film due to diffusion of moisture or glass through the lacquer. Shellac type paints followed by relatively low oxidizing top coats are normally used by spray gun. Due to its excellent adhesion, it is still in use by some mirror makers. It is applied directly on the silver film or on the copper coated silver. However, due to the bottleneck of shellac, it is applied on this film and a white lead paint covers it for further protection.

Silvering Solution

Several compositions for the preparation of silvering solutions are known, each having its own speciality. Besides the composition of silvering solution, other factors like temperature, time, light, amount of silver per unit area, and surface chemistry of glass influences the formation of the silvered mirror. A typical formulation of silver solution is given below:

(a) Solution C: Sugar Solution

Dissolve 2.5 gm of sugar in 25 ml of distilled water and add 1 ml drop of conc. HNO3 (Conc. Rs. Nitric acid S.gr. 1.42) and the solution is heated for 5 minutes and then cooled slowly.

(b) Solution B : Silver Nitrate Solution

i) 1 gm of KOH is dissolved in 25 ml of distilled water glass in a bottle.

ii) 1 gm of AgNO3 to 25 ml of distilled water in a separate glass bottle.

Then the solution (i) and (ii) are mixed and Ammonium Hydroxide Solution is added drop wise to form clear solution.

(c) Solution A

0.25 gms of Sncl2 is dissolved in 25 ml distilled water.

Sensitization of glass surface is carried out by pouring/spraying of Sncl3 solution on the surface of cleaned glass.

The silver nitrate solution mixed with sugar solution in the ratio of 2:1 is poured on the horizontal surface of glass in a dim light room. Excess water is removed after drying lead oxide protection coating is applied.

Quality Control and Standards

The following specifications have been formulated and published by the Bureau of Indian Standards, for guidance in maintenance of the quality of the product:

Production Capacity (Per annum)

Pollution Control

There is not much pollution in this industry. However, there should be proper arrangement for exhaust in spray booth, drainage for used water from the unit. It is advisable for the operator to use goggles to protect his eyes while handling the silver solution. The used water should be collected in a cement tank with proper arrangements for removal of such water at regular intervals.

Energy Conservation

This industry uses only electric power. Simple precautions and knowledge of effective utilisation of electric power could save energy.

Financial Aspects
A Fixed Capital

(iii) Machinery and Equipments

B. Working Capital (Per Month)
(i) Salary and Wages (per month)

(ii) Raw Materials (per month)

(iii) Utilities (per month)

(iv) Other Contingent Expenses (per month)

C. Total Capital Investment (Rs.)

Financial Analysis

(2) Turnover (per year)

(6) Break-even Point

Addresses of Machinery and Equipment Suppliers

1. M/s. Bando Trading Co. Ltd.
Tokashime, 770,
Jaipur
(For automatic bevelling machine Model - B-10)

2. M/s. Narang Glass and Frame Industries
2-1-77, Ridge Hyderabad - 2
(For mirror bevelling and edge cutting machine small type)

3. M/s. General Glass Machinery (P) Ltd.
F-13, Shanti Kunj, Sadhu Vishwani Road,
Punjab

Raw Material Suppliers

1. M/s. Carborandum Universal Ltd.
52/53, Jahangir Street,
Chennai - 600 001.
(For grinding media and wheels)

2. M/s. Kilburn and Co.
Mount Road,
Chennai - 600 002

3. M/s. Indo-Ashali Glass Co. Ltd.
Bhuru Kunda, P.O. Bhadani Nagar,
Distt. Hazaribagh, Jharkhand
(For Sheet/plate glass)

4. M/s. Triveni Sheet Glass Ltd.
Naini, Allahabad (UP)

5. M/s. Hindustan Pilkington Glass Industries
Asansol, (West Bengal)

6. M/s. Seraikells glass works (P) Ltd.
41, Hazra Road,
Kolkata - 700 010.

7. M/s. Haryana Sheet Glass Ltd.
F-24, Desh Bandhu Gupta
Market, Surindra Mansion,
Karol Bagh,
New Delhi - 110 005.

Contact for more information:

Information Manager
TIMEIS Project
E-mail: timeis@ficci.com