What are white knots?
When the rug is first strung upon the loom, the vertical strands known as the warp are wrapped around both the top and bottom of the structure. While the loom is being strung, some of the warp yarns are not long enough to continue the entire width of the rug. Instead of finishing the strand at either the top or the bottom of the loom, the weaver ties a knot between the incomplete warp and the new extension. When the knot is made, you can see the end of one warp, which after the rug is completed, translates to a white knot.
It is not unusual for a rug to have white knots as usually they are not visible. Often the white knots are either clipped or dyed at the rug weaving location. Sometimes rugs make it to the rug retail showroom with these white knots present. Although not well revered by some, others see them as part of the weaving process thereby adding character to their handmade piece.
Can White Knots be Eliminated?
Disguising and eliminating these knots may create problems down the road depending on the characteristics and condition of your rug. There are three common ways to treat a rug with white knots: punching the knot through to the reverse of the rug, clipping the white knot, and finally, dyeing the white knot. Some repair specialists may attempt to punch the knot through the face of the rug to the reverse side with a blunt object such as a nail. Depending on the condition of the rug, this solution may work well especially if your rug has a thick pile. If the knot is on the reverse side of the rug, this allows for the adjacent pile to compensate for space which is created closer towards the foundation which is a better cover up. Clipping the white knots is another effective solution, however the carpet must be in good condition with a full pile. The knot will still exist at the base of the carpet which still uses valuable space. Trimming this excess thread may be a good temporary fix, however, in a lower piled rug, a gap in the pile of the rug may be created where the knot once was. Another common practice by weavers or importers is to dye these knots the color of surrounding pile. However, a washing of a dyed rug may expose wash out the dyes, exposing these previously disguised white knots.
If a carpet is heavily worn, white knots may become more apparent and can probably only be remedied by dyeing. However if the rug has been worn, there is not much you can do other than attribute the white knots to being characteristic of a hand knotted piece. Remember, these imperfections are part of the structure of your carpet. You may want to discuss with your local repair specialist what would be the best alternative.
The above photograph shows what a white knot looks like prior to the warp weave. As you can see, the strand of cotton showing as excess from the knot will surface to the top of the pile if not trimmed.
The green arrows in Figure 2 show what white knots look like translated into the mix of a fully woven rug.
The arrow above in Figure 3 points to the best place to clip a white knot: directly above the knot. You do not want to disrupt the knot itself, as it is part of the structure your carpet is woven upon. Again, the use of a blunt object such as a nail can poke this knot through the face of the rug to the reverse side. This may be a preferable way to control the white knot as trimming may be difficult as you attempt to work around the desirable parts of the pile. Be careful when trimming!