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Monday, March 5, 2012

Hardwood Floors : Cleaning and Maintenance

Why Maintenance is Essential

To prevent hardwood floor damage, experts and manufacturers suggest numerous treatments. Yet even with regular maintenance, all hard wood floors will begin to deteriorate over time. Damage can range from fading, in high traffic areas, to extensive warping and cracking from moisture exposure. Treatment—whether by waxing or power sanding —ensures a good aesthetic, a sanitary floor and a safe, inhabitable space. Typically, maintenance depends on a few key factors: type of finish, wood grain and the extent of damage.

Damage Prevention & Simple Treatment

Following simple maintenance steps will help ensure that a hard wood floor looks its best. While regular sweeping is recommended on a daily (or at least weekly) basis to prevent soot from seeping into the wood, experts recommend utilizing a dry or damp mop instead of a saturated mop. Water tends to expand wood grain and may warp the floor, especially on unfinished surfaces. To avoid denting, consider using vacuums that feature brush attachments rather than machines with beater bars. Additionally, although covering floors will delay fading from use and sunlight, the World Floor Covering Association (www.wfca.org), suggests avoiding mats with rubber backing and those that are non-ventilated, as these textiles will tear at the surface of the wood.

Consulting a manufacturer or specialist about cleanser treatment is essential, as not all wood floors and finishes are compatible with the same treatment products. Therefore, it is essential to know the type of floor finish that is being processed. Most floors are coated with polyurethane, a durable plastic coating. Manufacturers supply pre-finished wood floors that have been UV dried and treated with polyurethane. Typically, these chemically treated floors are stain resistant, though the finish will eventually wear off. Hardwood floors that are treated with lacquer, varnish and shellac provide a shiny finish but do not resist stains and wear as well as polyurethane. Generally, denatured alcohol removes shellac and lacquer thinner, and acetone-based products are efficient for removing lacquer and varnish. Other wood floors are surface sealed with oil finishes, though these types of surfaces are typically coated with wax. Keep in mind that some paste waxes may require the use of a machine buffer.

As a general rule, experts recommend avoiding all oil-based soaps and waxes, specifically on polyurethane treated floors. Oil based wax sprays that accumulate create an unwanted film and a slippery floor, and may actually affect the re-coating process. Instead, a neutral pH cleaner is sufficient for most hardwood floors. For light treatment, a finish may be applied to fix fading. It is advised to apply coatings an hour apart. Additionally, finishing should be reserved for spot treatments for smaller areas of the wood surface.

Moderate to Heavy Damage

Screening is generally applicable to floors that have moderate damage. This process essentially involves utilizing a floor polisher to lift or abrade polyurethane finish off the wood without removing or cutting the floor. Experts advise that this process should be exclusive to floors with a polyurethane finish and floors that have not been treated with wax. Additionally, wood that is damaged beneath the finish is not compatible with this application, and should be sanded instead. Specialists note that it is essential to sweep the floor so that abrasives or dirt are not pushed into the surface during this process.

Power sanding may be essential to repair worn down areas of the finish and to treat heavy damage. Typically, a drum sander is employed, and it is advised to consult specialists for this procedure as the tool may gouge wood if it is not utilized properly. As a general guideline, a finish should be applied no more than 12 hours after a hard wood floor has been sanded. Typically, freshly sanded hard wood will absorb moisture and change color, which may adversely affect the finishing process.

Sometimes, corrosion will penetrate the finish of the wood, which will require extensive restoration. In the case of a flood, experts recommend the use of a mild alkali to scrub the contaminants from the wood surface. A trisodium phosphate is suitable for mildew scrubbing (and grease stains) and can be dried off with an absorbent cloth. For mildew build-up underneath the finish, it is essential to strip the coating. After sanding, experts may advise applying several applications of chlorine bleach to badly damaged parts of the wood. Afterwards, clean water may be used to rinse the wood, which should then be air dried. To prevent excessive warping and buckling, allow for sufficient drying time before the wood is refinished. For major damage where the wood is lifting, experts recommend nailing the wood to stop the damage from spreading.

Replacement of the wood may be necessary if the damage is too extensive. Some may opt to cover the wood with other materials like vinyl or carpeting or to replace the floor. Either way, consulting a contractor is recommended.

Sunday, March 4, 2012

Antireflection Coating

Antireflection coatings are optical coatings that are typically used to decrease an object’s reflectivity. Depending on the exact composition of a given antireflection coating, the extent to which reflectivity can be reduced varies. No matter how antireflective a coating is each antireflective coating is made the same way: alternating layers of materials with opposing refractive index are layered to block certain wavelengths of light and transmit the desired spectrum. Antireflective coatings are typically designed to affect infrared, visible or ultraviolet light, depending on the application, with some coatings blocking a greater range of light than others.

Product Variants: Types of Antireflection Coatings

Typically, antireflection coatings are classified based on the number of layers: single- or multi-layer. A third kind of antireflection coating, called absorbing antireflection coating, is also available.

Key Terms

When considering types of antireflection coating and optical coatings in general, it’s helpful to understand a coating’s relationship to wavelengths of light, as well as various key terms.

Thick-film If a coating is referred to as thick-film, the film is thicker than the wavelength of light hitting the coating. Of course, the effect a coating has on reflectivity will depend not only on the light’s wavelength, but the angle at which light hits the coating’s surface. Typically, thick-film coatings increase reflectivity.

Thin-Film A thin-film antireflection coating is one that features a thickness that is a quarter of the thickness of the wavelength of light. As a result of this ratio, thin-film antireflection coatings reduce reflectivity.

Thin-Film Interference Thin-film interference can occur when the upper and lower layers of an antireflective coating reflect incident light waves. These light waves then interfere with each other and merge to form another light wave. Thin-film interference can sometimes indicate the coating’s thickness or refractive index.

Other Considerations

Other terms, such as broadband, narrowband and dual band, are often used to describe the kind of spectrum of light an antireflective coating is designed to block. For example, some high-efficiency coatings block infrared light. Broadband coatings, on the other hand, reduce reflectivity over a wide range of wavelengths, which enables more light to be transmitted and enhances contrast in some optical applications. Depending on the exact spectrum of light that one is trying to transmit or block, one of these coating options may be appropriate.

Optical Coating

Optical coatings are used primarily to coat optical devices, such as lenses and mirrors, to alter the way light interacts with the device. Because optical devices depend on either the proper transmission or reflection of light, the presence of an optical coating enables the device to function properly and achieve the level of transmission or reflection

needed. The process by which an optical device is made more reflective is called silvering—highly reflective metals, such as aluminum and silver, are often used in optical coatings to silver an optical device. Optical devices that require minimized reflectivity, on the other hand, tend to benefit more from antireflection coatings. Product Variants: Types of Optical Coatings

Depending on the desired result—either increased or decreased reflectivity—various optical coatings can be applied to create or enhance a device’s properties.

Key Terms

There are several key terms that may help during optical coating selection: dielectric, refractive index, reflective, antireflective broadband, wavelength and visible spectrum.

Dielectric

A dielectric material is an insulator, meaning it is not a good conductor of electric current. However, dielectric materials can support electrostatic fields, with makes them relatively versatile materials.

Refractive Index

A refractive index, also called an index of refraction, is a measure of a material’s ability to slow down light waves as they pass through. A material’s index of refraction is determined by the ratio of the speed of light in a vacuum to the speed of light in the material.

Reflective

A reflective material does not transmit light waves, but rather bounces light waves back. A mirror is an example of a highly reflective material.

Antireflective

An antireflective material is the opposite of a reflective material. Instead of reflecting light waves, an antireflective material reduces reflection, which can, in some cases, improve contrast.

Broadband

The term broadband refers to having a wide band (and a continuous spectrum) of electromagnetic frequencies. Sunlight is an example of a type of broadband light radiation.

Wavelength

A wavelength is the distance between one peak of a wave and the next; in this context, between one peak of a wave of light and the next.

Visible Spectrum

The visible spectrum refers to the range of wavelengths of visible light radiations, as can be seen in the distribution of colors created when light is dispersed by a prism.

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