The $6,500 “Qum Silk” with Two Burn Behaviors
A client delivers an 8x10 rug bought at an estate sale as a “Persian Qum silk rug.” The label reads “100% silk, handmade,” and the price tag was $6,500. The rug is thin and tightly knotted with a high, cool sheen; the fringe is short and uniform. A burn test on several fringe fibers gives a hard black bead and the smell of burned hair. A second sample taken from the edge binding chars, smells like burning paper, and leaves a soft gray ash. The rug has a large irregular water stain and an orange rust ring near one corner. The client wants it washed, the sheen restored, and the rust removed before a dinner party in six days. Your standard wash uses an alkaline detergent at pH 10, a mechanical wringer, and a heated drying room. The client says, “Silk is silk-just be careful.”
1. Interpret the conflicting burn tests. What is the likely construction, and what additional tests would you run?
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The tests conflict because they sampled different materials. A hard black bead and burned-hair odor indicate a protein fiber-silk or wool. A paper-like char and soft gray ash indicate a cellulosic fiber-cotton, rayon/viscose, or mercerized cotton. The fringe is often cotton even on a silk rug, so the fringe test alone cannot identify the pile. The edge binding may also be cotton. I would separate pile, fringe, and binding samples, then confirm with a microscope (silk is smooth and rod-like; cotton is ribbon-like and twisted) and a solubility test. I would also check whether the “silk” is mercerized cotton, which has a similar sheen but is cellulosic. The likely construction is silk pile with a cotton foundation and fringe, but that must be confirmed before washing.
2. Given your standard pH 10 wash and mechanical wringer, what risks apply, and what modified procedure would you use?
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A pH 10 wash and mechanical wringer are risky for both silk and cotton. Silk is sensitive to alkali: high pH can dull the sheen, yellow the fiber, and reduce strength. Cotton foundation can shrink, and a wringer can distort the pile and crush the fringe. If the pile includes viscose/rayon, wet strength is low and abrasion can damage it.
Modified procedure: use a neutral detergent at pH 7 or below, cool water, very short dwell, and gentle hand work rather than a wringer. Support the rug on a screen and avoid hanging it wet. Extract with low pressure, rinse to neutral, and dry flat with airflow. If the pile is confirmed as silk, I would avoid enzymes and alkaline builders. If the “silk” is actually mercerized cotton, the same gentle approach still applies, but I would watch for shrinkage. I would test the rust remover on a hidden area first because acids that remove rust can also affect dyes and silk.
3. How do you handle the rust ring and the client’s expectation of restored sheen?
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Rust: the orange ring is probably iron oxide transfer from a metal object. I would use a gel or poultice-style rust remover so the acid stays local, test it on a hidden area, and keep dwell time short. I would not use chlorine bleach, which can damage silk and shift dyes. After treatment I would flush and extract quickly. The rust may leave a permanent shadow if it has stained the fiber.
Sheen: proper rinsing and fast, flat drying can improve dullness caused by soil or residue, but it cannot restore luster to fiber that has been abraded or chemically damaged. I would avoid silicone polishes, which attract soil. I would tell the client that “restored sheen” is an appearance improvement, not a guarantee, and document the pre-existing water stain and rust ring. If the rug is a mixed-fiber construction, I would also note that in writing.