Glass wool - AbsoluteAstronomy.com

Glass wool or fiberglass insulation (US) is an insulating

Thermal insulation

Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

material made from fiberglass

Fiberglass

Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

, arranged into a texture similar to wool

Wool

Wool is the textile fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, vicuña, alpaca, camel from animals in the camel family, and angora from rabbits....

. Glass wool is produced in rolls or in slabs, with different thermal and mechanical properties.

Manufacturing process

After the fusion of a mixture of natural sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

and recycled glass at 1,450 °C, the glass that is produced is converted into fibers. It is typically produced in a method similar to making candy floss, forced through a fine mesh by centrifugal force, cooling on contact with the air. The cohesion and mechanical strength of the product is obtained by the presence of a binder

Binder (material)

-See also:*Adhesive or Glue*Cement*Paint...

that “cements” the fibers together. Ideally, a drop of bonder is placed at each fiber intersection. This fiber mat is then heated to around 200 °C to polymerize the resin

Resin

Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...

and is calendered to give it strength and stability. The final stage involves cutting the wool and packing it in rolls or panels under very high pressure before palletizing the finished product in order to facilitate transport and storage.

Uses

Glass wool is a thermal insulation

Thermal insulation

that consists of intertwined and flexible glass fibers, which causes it to "package" air, resulting in a low density

Density

The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

that can be varied through compression and binder content. It can be a loose fill material, blown into attics, or, together with an active binder sprayed on the underside of structures, sheets and panels that can be used to insulate flat surfaces such as cavity wall insulation

Cavity wall insulation

Cavity wall insulation is used to reduce heat loss through a cavity wall by filling the air space with a porous material. This immobilises the air within the cavity , preventing convection, and can substantially reduce space heating costs.During construction of new buildings, cavities are often...

, ceiling tiles, curtain wall

Curtain wall

A curtain wall is an outer covering of a building in which the outer walls are non-structural, but merely keep out the weather. As the curtain wall is non-structural it can be made of a lightweight material reducing construction costs. When glass is used as the curtain wall, a great advantage is...

s as well as ducting

Duct (HVAC)

Ducts are used in heating, ventilation, and air conditioning to deliver and remove air. These needed airflows include, for example, supply air, return air, and exhaust air. Ducts also deliver, most commonly as part of the supply air, ventilation air...

. It is also used to insulate piping

Pipe insulation

Pipe Insulation is thermal or acoustic insulation used on pipework.-Condensation control:Where pipes operate at below-ambient temperatures, the potential exists for water vapour to condense on the pipe surface...

and for soundproofing

Soundproofing

Soundproofing is any means of reducing the sound pressure with respect to a specified sound source and receptor. There are several basic approaches to reducing sound: increasing the distance between source and receiver, using noise barriers to reflect or absorb the energy of the sound waves, using...

Fiberglass batts and blankets

Batts are precut, whereas blankets are available in continuous rolls. Compressing the material reduces its effectiveness. Cutting it to accommodate electrical boxes and other obstructions allows air a free path to cross through the wall cavity. One can install batts in two layers across an unfinished attic floor, perpendicular to each other, for increased effectiveness at preventing heat bridging. Blankets can cover joists and studs as well as the space between them. Batts can be challenging and unpleasant to hang under floors between joists; straps, or staple cloth or wire mesh across joists, can hold it up.

Gaps between batts (bypasses) can become sites of air infiltration or condensation (both of which reduce the effectiveness of the insulation) and requires strict attention during the installation. By the same token careful weatherization

Weatherization

Weatherization or weatherproofing is the practice of protecting a building and its interior from the elements, particularly from sunlight, precipitation, and wind, and of modifying a building to reduce energy consumption and optimize energy efficiency.Weatherization is distinct from building...

and installation of vapour barriers is required to ensure that the batts perform optimally. Air infiltration can be also reduced by adding a layer of cellulose loose-fill on top of the material.

Studies of side effects

A 2002 summary by International Agency for Research on Cancer

International Agency for Research on Cancer

The International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....

puts insulation glass wool into Category 3 carcinogen, "not classifiable as to its carcinogenicity to humans". The summary found "inadequate evidence" of glass wool causing cancer in humans and "limited evidence" of it causing cancer in experimental animals. Two unspecified "large" studies reviewed in the summary showed "increased mortality" (6% in the "US cohort study") from respiratory cancer in workers exposed to glass wool production. The longevity of exposure did not affect mortality. Smoking habits were not factored out. Non-occupational indoor settings were found to contain "much lower" fibres per volume unit.

Unspecified studies reviewed by Health Canada

Health Canada

Health Canada is the department of the government of Canada with responsibility for national public health.The current Minister of Health is Leona Aglukkaq, a Conservative Member of Parliament appointed to the position by Prime Minister Stephen Harper.-Branches, regions and agencies:Health Canada...

have shown that short time exposure to glass wool may cause minor irritation of skin, eyes, nose and throat. According to Health Canada, glass wool exposure does not present a significant health risk to the general population.