Older textiles and furnishings, especially those with a cellulosic fiber such as cotton, flax (linen), jute and similar fibers, can slowly degrade over time—sometimes years or decades. This lengthy, slow but relentless deterioration and weakening of the fibers leads to eventual damage that can be seen as rips, tears, slits or other structural damage in the fabric, carpet or rug. It may take a few years for dry rot to manifest itself, or it can take decades; sometimes 40 to 50 years or more. This misnomer “dry rot” implies that the rotting or damage took place in the absence of moisture, whereas the damage was previously done during some conditions of wetness and mildew. It is understood that although presently "dry," there were actually preexisting conditions creating localized or smaller, concentrated areas of moisture buildup and damaging fungus growth therein. Once dry, the result is weakened fibers that can easily be broken and have a dry appearance, feel or sound.

One condition that may have contributed to the onset of dry rot is prior uncontrolled wetness for long periods of time. Typical of this is the section of rug or carpet underneath plant pots, especially those planters made of clay that can transpire moisture and dampness into the carpet.

Another contributing factor may be residues in the base of the rug or carpet such as those typical of animal pet stains. Buildup of salts from pet stains become hygroscopic and thus "moisture attracting” and keep that section slightly damp for long periods of time. This condition in the textiles can thus cause moisture to be continually absorbed from the air and dampness to accumulate in the rug or fabric. The result is a slow but continual process of fungus growth and deterioration in the affected fibers or yarns of the rug or fabric. Rugs suffering from this condition may often smell during hot humid weather. The most common type of damage from dry rot occurs in cellulosic fibers that often make up the foundation (or unitary backing) of rugs and some woven carpet. Although the rug pile or face yarns may be wool or another fiber, it is actually the backing or foundation fibers that are more likely to be damaged. This ongoing condition of dry rot shows no outward or obvious signs while the damage is slowly accumulating. That is, until the real damage is done and some normal moving or handling of the textile brings this latent condition to light.

But eventually the affected yarns become stiffer, less supple and eventually brittleness sets in. This later condition typically results in a subtle but distinctive "crackling" or "snapping" sound when, for example, an older rug or carpet is bent or rolled between the hands. Very fine quality, very dense or tightly knotted Oriental rugs are especially prone to such damage. In advanced conditions, merely lifting or moving the rug, textile or fabric for cleaning or restoration can result in slits, rips or tears in the foundation of the rug, carpet, tapestry or fabric.. It is not caused by the customary and normal handling, but by the progressive "silent" damage that has been occurring for years before.

Unfortunately there's no remedy to reverse this premature aging process in the affected fibers. The damage has already been done and has occurred due to preexisting conditions during use. The prescription is for a careful, thorough professional cleaning and then any additional repairs needed to rebuild or reinforce the area of obvious damage. An antimicrobial/antifungal treatment to arrest some of the inherent conditions leading to damage may also be considered, but there's no assurance that the dry rot will not appear again in the same or other areas of your rug or textile in the future.