This is a popular clasp I've seen around and recently I've been using it a lot more because it's a lot easier to put on than fiddling with a button with one hand. Essentially a bracelet band can be widened without breaking the loop:
This relies on a square knot's ability to slide along its base cords.
It's mainly used in bracelets because you would need an awkwardly long sliding cord for necklaces or anklets. It takes a lot less extension to get over a hand than say, a head.
A) Place a bead or some kind of bulky knot at the end so the slide clasp can't get pulled out completely.
(ngl I carefully drew the bead attached with a lark's head knot like an idiot but in practice if you followed the picture the bead would come right off. Don't. Don't do that. Loop the bead on the cord and secure it with an overhand knot.)
B) Leave a section of base cord blank. Make it slightly longer than you want the cord to be able to slide. 3in. is a good length, not including cord for holding the bead.
C) Start your project with a square knot starter, no overhand knot.
D) Build the bracelet/project to almost the final length. Don't count sections A and B in the bracelet length.
Finishing the slide clasp:
^When you get about half an inch to the end length of your project use an overhand knot to secure the base cords only.
Line the starter up to cover the ending's overhand knot and continue the bracelet without any gaps:
A sequence of 3 or 4 square knots works fine.
^The result should look like this.
A) The base cord's overhand knot is hidden beneath the sliding cord.
B) The outer cord is secured by an overhand knot also hidden beneath the sliding cord. Do not include the sliding cord in the overhand knots. This allows the cords to slide within the square knot sequence.
I personally prefer a single slider but most sliding clasps I've seen other people make have two sliding cords held together by a short independent square knot sequence. It looks like this:
It's good if your style is to start in the middle of a bracelet and work outwards twice, giving you two bracelet endings and no 'start.' This isn't really my style but it's good to mention.
^Sections A and B are the ends of the same bracelet. Overhand knots made more obvious. Section C is a short square knot sequence made from a new cord, not repurposed from the bracelet.
((Also,,, I am straight-up SQUINTING at my past self. Another mistake- there is one cord folded over used to make the outer cords in section C and there shouldn't be 4 strings coming out of its ending overhand knot.))
So in Macra-May 2024 I made this spectral line bar bracelet:
I didn't mention it at the time but it was secretly given a slide clasp:
