Studies have shown that microfiber cloths are more effective at removing particulates, including germs, from surfaces than other types of cloths. Since their introduction into the market in the 1990s, they have been incorporated into glazing cleaning protocols for framed works and display cases in many museums, galleries, frame shops, and homes. Compared to other cleaning materials, microfiber cloths also tend to be less abrasive, which helps prevent micro scratches on standard acrylics, maintaining clarity longer[i]. As technologies have advanced, a greater number of options are now at our disposal. We started our investigation wondering what makes one microfiber cloth better at cleaning glazing than another. What we found is that there is no definitive “Best Cloth.” The environment one is in and how one cleans can influence which cloth is most appropriate for the job.
What are we removing off the glazing surface?
Let’s first start with what exactly we are cleaning off the glazing: There are two main types of materials routinely removed from glazing: fingerprints, which are oil based, and dust. Dust particles are made up of a variety of airborne organic and inorganic components, including soils, dried skin, fibers from clothes, spores, and particles from new construction which include silica, sawdust, cement dust and other sharp and abrasive materials.
What makes one cloth more effective than another?
The efficiency of a microfiber cloth to clean both fingerprints and dust is dependent on the fiber content, how fine the fibers are, the weave structure, and the density of the weave. Most microfiber cloths designed for cleaning (as opposed to clothing or other applications) are either 100% polyester or a mixture of polyester and nylon (also referred to as polyamide). The blends of polyester and nylon are made during the manufacturing of the fiber, not as mixture of separate fibers as is the case with natural fibers. The two synthetic polymers are combined and extruded as one continuous fiber: Nylon is used for the ridged, star-shaped core structure, and wider polyester wedges fit within the nylon ridges (see Fig. 1). The wider polyester part of the fiber is what becomes compressed when pushed against the surface being cleaned, ‘scraping’ the surface for the dirt to enter between the gaps of polyester and nylon. Polyester has a tendency to bounce back to its original shape, so the cloths do not lose their efficacy and can be washed and re-used multiple times.
Static charge between the fibers also plays a part in removing materials off the glazing surface: An electrostatic charge is generated between the two polymers due to their different tendencies to give up and receive electrons (known as a triboelectric effect). This effect serves well to pick up both positive and negatively charged materials. Inorganic dirt, for example, is made up of particles which mostly contain a positive charge. Spores, mycelia and conidia, on the other hand, have a negative charge.
Typical blends are 70/30 and 80/20, the first number referring to the percentage of polyester and the second to nylon. Unlike cotton, which binds well with water but needs surfactants / detergents to pick up oils, polyester is highly hydrophobic, binding well with oils. Because of this, polyester lifts oil based marks, such as fingerprints, off glazing without the need of a surfactant[ii].
Microfibers are extremely fine, much finer than human hair: By definition, they are one decitex or less and ultra-microfibers are 1/3 decitex. Decitex is a unit quantifying how fine a fiber is by its weight and length: 1 decitex weighs one gram and measures 10,000 meters. In order to achieve this level of fineness and still be manageable, bundles of polymers are split into finer fibers by a chemical process after the cloth is woven. These fine filaments provide strong capillary action, drawing in 8 to 25 times their weight in water.
A cloth’s weave structure and weave density play a role in how many fibers are in contact with a surface, and in the quantity of liquid take-up. Weave structures tend to be either loop, flat, knit, non-woven, or in some cases, such as with some ultra-suede types, a combination of two structures. The denser the weave the more efficient, as there are more fibers and in turn more surface area available to gather particulates.
When it comes to cleaning glazing, there are pros and cons to different weave structures. Loop structures have a higher surface area per volume and are therefore better at absorbing and capturing surface dust. But they are also better at snagging on sharp bits of frame moldings and burrs along glazing edges. Looped material is also more likely to pick up extraneous particulates, such as saw dust and glass shards in the typical frame shop. Once particles are embedded, the softest cloth can become abrasive. On a nano level, microfibers can also catch and leave lint within the crevices of a glass or acrylic surface. This is why microfiber cloths designed for cleaning eye glasses are smooth: although less absorbent, they are less likely to pick up extraneous matter.
Is one microfiber more abrasive than another?
While we have heard anecdotal references to certain weave structures and polymer ratios affecting abrasion, we have not encountered published studies on this specific topic. One key component in reducing the risk of abrasion when cleaning is the solvent used. Research on cleaning plastic materials in museum collections has found that using a detergent solution, such as Orvus WA paste in distilled water, can act as a lubricant and reduce scratching.
Another factor to consider when looking at risks of abrasion is how the edges of the cloth are treated. Some cloths are finished with a surged edge using a hard synthetic thread. For ultra suede variety cloths, these sharp edges can be cut off with pinking shears. Loop weaves tend to fray if cut, regardless of the types of shears used (see Fig. 2). Some cloths are so densely woven that they do not fray at all when cut.
The cleaning method
Cleaning methods are just as important to prevent scratching and abrasion as what type of cloth and cleaning solvent is used. Continually folding to expose an area of clean cloth during the cleaning process helps keep dirty areas of cloth away from the glazing surface. One cleaning study concluded that wiping in a linear motion removes dust from surfaces, while circular motions merely redistributes said dust which potentially leads to scratching.
As most suppliers point out, cloths can be washed and reused multiple times and are considered to be part of a sustainable practice. Concerns over the effects of microfibers released into our oceans and water ways, however, are valid, as these synthetics are not biodegradable. One option is to place the cloths in a bag specifically designed for catching fibers in the wash.
Special thanks to Anna Lagana, Research Specialist at the Getty Conservation Insitute; Bill Wei, Senior Conservation Scientist at the Netherlands Institute of Cultural Heritage; and Terry Treacy, Vice President of Marketing at SSI Products for their generosity in sharing their expertise and taking the time to answer our questions.
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[i] Casella, Luisa and Camille Moore. 2009. “Research on the Methods for Cleaning Face-Mounted Photographs”. Topics in Photographic Preservation, Volume 13. American Institute for Conservation Photographic Materials Group Winter Meeting, Tucson, Arizona.
[ii] Hartog, F. and H. Porter. 2017. “The Powers of Microfibre Cloth”. Forum of the Institute of Conservation Textile Group edited by Sarah Glenn and Katie Smith. Bath: ICON Textile Group. 41-48.