Lacing on to the apron rod is ideal if your yarn is jumpy like linen or slippery like rayon or so expensive you don’t want to waste an inch. . This is also good for very dense warps when there isn’t room to tie knots on the apron rod.To lace on, you divide the warp into 1″ bundles, knotted at the end. Using a slippery cord, lace the cord through the bundles and around the apron rod. Details are given below. I like to use slip knots at the end of the warp bundles. That way, if I later find a threading error, I can easily untie the bundle to make a correction. Slip knots take more warp than overhand knots, though, so if warp is precious, you may want to use overhand knots. However, it’s fairly difficult to untie the overhand knot to correct an error. You may be able to pick it open with a strong tapestry needle or a nail.
A slip knot is a temporary knot that secures a single thread or groups of threads. Its greatest asset is that it can be quickly untied with a jerk with one hand. It’s often used to tie groups of warp ends after they have been threaded in the heddles so they won’t slip out. Every weaver should know the slip knot because it is used so often-whenever you want to secure something temporarily. It’s my favorite knot, and it’s the one I almost always automatically tie-just in case I’ll need to undo it.
To make a slip knot: To make the first loop, you can use either the tail or the standing end, whichever seems easier to tie in the situation. In this example I’m using the standing end, but you could just as easily make the loop with the tail and proceed as follows.
Reach through the loop with the right forefinger and thumb and grasp the standing end and pull it through the loop, so that it makes a loop within the first loop. (If you were to begin the knot with the tail making the first loop, and the tail were being drawn through as the second loop, make sure you pull the tail only part way through, not completely through. If you pulled the tail through, you wouldn’t have the second loop.)
To release the knot: Just jerk on the end you made the loops with, in this case the standing end.
More information is in “Weaving for Beginners”
The above tip is an excerpt from Book 2: “Warping Your Loom and Tying On New Warps”
The main tricks to lacing on are given on pages 64 and 65 in the “Tying On” chapter. The Slip Knot is just one of many knots described in detail from the “Knots” chapter.