Rug Repair Part 5: Curling Edges

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Last time we discussed sides and selvage repair. Now we will look at curling edges - why rugs won’t lay flat and how to correct it.

The corners and edges of rugs often curl up. These problems, unsightly and potentially hazardous, will only get worse with time causing wear and damage that is expensive to repair.

So why does this happen and what can be done?

The causes are varied and understanding why a rug is curling is often the first step in determining how to correct the problem. The remedies are often blocking with sizing applied and sometimes sewing.

Many lightweight machine-made rugs have sizing applied to the back that stiffens them preventing curling or wrinkling. Sizing treatments can be gelatin or thin coatings of adhesives which break down over time, or with cleaning, causing the rug to “soften” and curl at the edges. Foot traffic can make the problem worse, causing the edges of “Belgian” or face-to-face woven Wilton rugs to curl over and eventually break or split when left untreated.

Hand-knotted rugs curl for various reasons, but the most common cause is uneven weft tension at the sides. Weavers must carefully control weft tension at the edges of rugs. Too loose and the sides will be weak, or “wavy,” not laying flat. Too tight and the sides can curl under. The usual solution is to weave edges tight and attempt to keep them from curling by sizing, or adding vinyl strips (often seen on the back of Persian rugs). These remedies usually fail with the sides curling under the rug.

Many hand-knotted rugs no longer have integrated woven selvages. This is because the rug was cut from the loom and then re-selvaged using various methods during the finishing process. This is commonly seen in modern Pakistani, Indian and some Iranian rugs. Adding new selvage “cords,” and/or overcasting the cut edge with wool finish cut selvages is one cause. Sewn on cords applied too tight will cause rippling. Tension cords used in overcasting can cause edges to ripple if they are adjusted too tight or if they shrink during cleaning.

So what are the repair options?

Blocking and sizing can help most end and side rippling (Image 1). The sides of a rug are tacked to a blocking floor under tension, then steamed or moistened to cause them to soften and change shape (Images 2-5). Sizing may then be applied to help the rug hold its shape. Sizing is very much like starching a shirt collar, but, in rugs, stronger sizing agents are used. Organic sizing materials may be starch or gelatin. Synthetic sizing products are typically white glue thinned with water or good quality carpet seam adhesive diluted with 3-4 parts water. Organic sizing materials are reversible and while synthetic ones are not, they are more effective in causing a rug to hold its shape.   

Sides can be tacked and sized or entire rugs may be tacked and sized depending on the problem to be solved. Be sure to allow sizing to dry completely before tacking the rug up.

Vinyl strips can also be sewn to the back of the sides to prevent curling (which over time could cause differential wear). Finely woven hand-knotted rugs can also have a special stitch put into the sides that stiffens edges and helps prevent curling (Image 6-7). Often a combination of these treatments is required to correct the problem. 


Part 1: An Introduction to Rug Conservation, Restoration and Repair

Part 2: Rug-End Securing

Part 3: How to Deal with Worn Fringes

Part 4: Sides and Selvages

Part 5: Curling Edges – Why Rugs Won’t Lay Flat and How to Correct it

Part 6: Torn Corners and How to Repair the Problem


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