Hi Rabbi Mendy, What's the rule for checking tzitzit to be kosher? I washed some of mine and there may be loose knots etc. Thank you!
There are a number of laws involved. But for starters see if all of the 4 sides ends still have 2 knots and then tighten them while saying "Lshem Mitzvat Tzitzit". As well make sure all sides have 8 strings. If any of this is missing let me know.
When washing tzitzit the best way is to tie the strings all together in a knot that can be undone. Put it in a the bag with holes that is usually used for sensitive materials. You will see how when it comes out it stays pretty good for the most part.