ECOLOGY and COATINGS

Post 359 – by Gautam Shah 

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Coatings (Paint, Varnish, etc.) consist of organic as well as inorganic substances. Both the categories of materials can be hazardous at several levels such as: production, application, curing or drying, functional use, and disposal level.

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At production level the handling and use of certain raw materials can be hazardous. Typically handling of extenders and pigments can pose air-bourne particle spread. Some of these silica containing materials are toxic and carcinogenic and not eco-friendly. Resins (amino) with styrene and formaldehyde are carcinogenic. Solvents are known fire prone materials. At application level, the primary hazard occurs, due to high amounts of volatile organic content going into air. Its vapours or odours are noxious, allergic and unpleasant. The odour suppressants added to coatings are not necessarily benign. At application level, old coated surfaces are rubbed or scrapped, the particulate matter of which causes air pollution and the constituents are often unfamiliar.

Aerosols cause high level of air pollution

 

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Post application, the wearing surfaces and peel-off cause, dust pollution. Some of the plastic materials continue to deteriorate, evolving pollutants. Coatings used on kitchen shelves, utensils, equipments cause contamination. Accidental high heating and fire scorch a coating. Planned removal of coating by sanding and chemical etchings (paint scrubbers or removers) can also leave unwanted residual products. Disposal of coated items by sawing, forced removal, hammering, chiselling, sanding, scrapping, etc. can desecrate the environment.

PIGMENTSProlonged or high intensity exposure to paint and paint fumes can affect three main organs, lungs, kidney and lever. These manifest as headache, allergies and asthmatic reactions, irritation of skin and eyes, burning in nose, airways, urinary tracts.

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The trend world over is to design entities with their own or integrated surfaces. A variety of metal and polymer surface treatments are available that molecularly change the quality of the surface. Such `surface systems‘, rather than `surface finishes‘ often do not require any application of foreign substances. A variety of single or a combination of treatments like temperature, radiation, sonar, mechanical finishing, stress induction and relief, cathodic protection etc. can eliminate organic coating systems. Such surfaces do not have any applied finishes, but rather have a generated finish.

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There are many inorganic coating systems that are akin to metalizing systems. In such systems the role of medium is to carry and spread the pigment and other substances. On baking or firing the medium is evaporated or burnt off leaving metallic or alloying compounds on the surface. Such substances are generally heat or flame cured to cross links with the substrate material.

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INDOOR AIR

Post by Gautam Shah

An Interior Space has finite volume, but with very average level of exchange with outside environment. Interior spaces can support a moderate level of human occupation and of certain intensity but for fixed duration. In excessively polluted localities it cannot offer the comfort and health safety beyond a limited period.

Quality of outdoor air determines the quality of Indoor air

Outside air is always fresher due to its infinite volume, air currents, solar radiation and other environmental processes of nature. Though external air in highly polluted surroundings could be inimical, during specific periods. For buildings, at micro climate level, the exterior air may be contaminated on specific sides and periods of the day.

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Indoor air quality in buildings can be improved, by control at the source, by filtration techniques, and by passive and active means of ventilation to dilute contaminants. Inadequate exchange (ventilation) can increase indoor pollution level by not bringing in enough and quality outdoor air to dilute the pollutants in indoor air. High temperature, humidity levels and to some extent air movements also increase concentrations of some pollutants.

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To refresh the interior environment, one needs passive and benign interaction with the exteriors. The benign interaction could be scheduled in terms of time, such as during periods when outside environment is better, or facilitating the exchange on faces that are less vulnerable to exterior fouling, such as off the road sides, terraces, etc.

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Contamination of Interior Spaces is not related to occupancy, but it may continue in dormant periods also. Many of the contaminants evolve from building’s materials, furniture, furnishings, cleaning and maintenance products, and as after effects of processes (such condensation of vapours, deposition of airborne particles, bacterial growth, etc.). The contaminants include unwanted gases, excess moisture, volatile organic compounds (VOCs), odours, particulate matters, etc.

Poor indoor air quality can cause or contribute to the development of infections, lung cancer, and chronic lung diseases such as asthma. In addition, it can cause headaches, dry eyes, nasal congestion, nausea and fatigue. People, who already have lung disease are at greater risk.

Formaldehyde is a carcinogenic substance and also causes coughing, eye, nose, and throat irritation, skin rashes, headaches, and dizziness. It is a very common chemical group found in many substances such as adhesives, paints, dyes, processed and printed fabrics, carpets, upholstery, particle board, and plywoods. Formaldehyde continues to get released in the air. Similarly many types potentially harmful chemicals are emitted by household cleaning agents, personal care products, pesticides, paints, hobby products, and solvents. Such chemicals can cause dizziness, nausea, allergic reactions, eye, skin and respiratory-tract irritation.

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Some simple strategies to improve Quality of Indoor Air

1 Design wise isolate areas of high contamination by controlled partitioning system from benign areas.

2 Recognize the role of cracks and crevices for micro ventilation in buildings of warm climates, compared with a tightly sealed entity designed to avoid heat loss in buildings of colder climates.

3 Schedule activities and locate processes in areas where passive exchange with the outdoors is available.

4 Interior Design must include products and processes with least or zero VOC emissions.

5 Use cleaning and maintenance products that emit low or zero VOCs.

6 Plan for Air Moisture Control by way of ventilation, diffusion and scrubbing.

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