Photo © Michael Chusid
The impact of friability goes beyond the panel appearance and durability. The particles released by mineral fiber products may contain crystalline silica. One major manufacturer’s safety data sheet cautions, “Be certain the work site is well ventilated and avoid breathing dust. Exposures to respirable crystalline silica…must be determined by workplace hygiene testing. Prolonged and repeated exposure to airborne free respirable crystalline silica can result in lung disease (i.e. silicosis) and/or lung cancer…” Since particles may also be combustible, the same safety data sheet warns, “Dust deposits should not be allowed to accumulate on surfaces, as these may form an explosive mixture…”
Sag
After panels are conditioned to a stable ambient temperature and humidity, they are exposed to elevated temperature and humidity, and any of the humidity-induced sag is recorded. The panels are then returned to the initial temperature and humidity, and the recovery sag is recorded. In most cases, the recovery sag represents a permanent deformation. The results of exposure to ambient humidity also suggest how a product responds to moisture exposure via leaks, condensation, and other sources of liquid water (Figure 2).
Transverse strength
Images courtesy Ceilume
Panels are tested in a hydraulic machine, and the load is noted at which the panel breaks or yields and is unable to carry additional loads. The modulus of rupture (flexural strength) is then calculated. A larger modulus indicates greater strength and break resistance.
According to ASTM C367, “Performance characteristics in the handling, shipping, and installing of acoustical tiles or panels are often predicted by strength testing.”
Breakage can also occur during maintenance activities when panels may be moved for above-ceiling access. While new construction employs trained installers, maintenance is frequently performed by untrained tradespersons who are more likely to cause breakage (Figure 3).
Discussion
Thermoformed panel strength properties are at least an order of magnitude superior to the mineral fiber panels in all categories. The results of the tests are summarized in Figure 4.
Stain resistance
ASTM D1308, Standard Test Method for Effect of Household Chemicals on Clear and Pigmented Organic Finishes, “covers determination of the effect of household chemicals… resulting in any objectionable alteration in the surface, such as discoloration, change in gloss, blistering, softening, swelling, loss of adhesion, or special phenomena.”
While developed to test coatings with household chemicals, the test methodology is frequently applied to diverse types of interior finishes and with chemicals used in industrial, healthcare, and commercial facilities.
Interior finishes often ‘ugly out’ before wearing out. For example, many acoustic ceiling panels are difficult to clean and end up landfilled when they become unsightly. In contrast, stain-resistant and cleanable ceiling panels offer significant advantages in sustainability, economics, and life-cycle performance (Figure 5).
Ceilings are the part of a room in the least physical contact with occupants, yet they are exposed to dirt, grime, and stains from a variety of sources. Air currents from diffusers or ordinary convection carry dust, soot, and aerosols onto ceilings. Everyday substances splash, squirt, or spray upward. Water from leaks, spills, and condensation cause stains and mold on common mineral fiber acoustic ceilings. Panels in suspended ceilings can also get dirty when handled for maintenance access above the ceiling. Despite this, reliable data on ceiling stainability and cleanability has been difficult to find.
