Specific Types of Knots – Applications of Kosheir and Mattir

Single Knots

A single knot formed by looping together two ends of a string, as is normal to tie as the first step of tying shoelaces, may be tied on Shabbos, even with the intention for it to last indefinitely. This is not considered a knot at all by the criteria of these melachos of kosheir and mattir, as such a knot is very loose and easily comes apart.
However, one may not tie a single knot on top of a pre-existing single knot as this makes it into a double knot (SSK 15:54).

A bow without an underlying knot is also not considered a knot and may be tied on Shabbos, even to last indefinitely. A further bow may even be tied on top of this, though a single knot may not, as this produces a tight knot (SA 317:5, MB 29, BH”L Aniva, SSK 15:57).

A knot which consists of an underlying single knot with a bow on top, such as one normally ties on ones shoes, or the belt of a dress, is considered an ‘unskilled’ knot.
Therefore, it may be tied with the intention to last for less than 24h but not longer (as above, this is only permissible if one intends to tie it for less than 24h and it is a type of knot that is society’s or one’s personal norm to tie for less than 24h, or a type of knot which has no ‘norm’ so depends on the intention when tying it) (R 317:5, SSK 15:56).

In a case of need, one may tie a further knot on top of a single knot plus bow (such as one would do on a shoe to strengthen the first knot and bow), to last for less than 24h.
- Such a knot is more lenient than a double knot given that it is looser, and as by pulling one end of the string the top knot and bow become undone.
For example, if one’s child’s shoelaces keep coming undone, one may tie a further knot on top of the underlying knot plus bow to last for less than 24h (SSK 15:56, OS 10 fn28).

There are a number of different types of knots that can be made in a necktie. These fall in to two main categories, which have different halachos:
- Knots which fall apart entirely when one removes one end of the tie, leaving no knot left, are treated like unskilled knots so may be tied for less than 24h.
- Certain types of knots do not entirely fall apart when removing one end of the tie – they leave a knot in one end of the tie, a bit like the type of knot one gets one tying one end of a string back on to itself. It is questionable whether such knots may be tied even for less than 24h; one should consult with one’s Rav for practical guidance (SSK 15:62, fn 208, OS 10:23).

A one-off unskilled knot which is temporary, inevitably going to be opened in the near future and will not be re-tied afterwards, may be undone even if it happens to have been tied for more than 24h.
- For example if a packet of food is tied with a ribbon that needs removing before being able to open the packet, it may be opened. (SA 317:3, MB 21, SSK 9:15, fn60).

SSK (Shmiras Shabbos Kehilchasa) is strict to treat the twisting and untwisting of metal twist ties (which are used to close the tops of plastic bags etc) as tying and untying; therefore they should not be twisted to last for more than 24h or untwisted having been in place for more than 24h.
- Other poskim are lenient saying there is no concern in twisting and untwisting such twist ties – consult a Rav for practical guidance (SSK 9:14, Dirshu 317:41).

If one was trying to tie a bow on top of a single knot (like one does on shoes) and it went wrong and one accidentally ended up with a double-knot, it may be undone.
- Even though generally we are strict not to untie double knots, when there was no intent tie tie it in the first place we are lenient (MB 317:23, SSK 15:60, OS 10:7)

A knot which may not be untied on Shabbos may also not be cut through.
Even a knot which may be untied on Shabbos may only be cut through if one is unable to untie it and this should not be done in front of an unlearned person lest they overextend this leniency (to knots which are forbidden to untie).
However, one is permitted to cut through string if it is not in the place on the knot, if done in a destructive fashion, to access an item which it enwraps (MB 317:23, SSK 15:58, 9 fn60).