I like to fix my recorders the way they came ie waxed string,waxed sting,cork then cork,just because I like that,regarding cork, you can buy cork sheets from music medics in packs of 10?,(around $46 )would probably last you a lifetime,you can buy the thickness you know u want ,or you can buy a mixed pack of thicknesses,which would suit all your different flutes ,and share with recorder friends,also as a QUICK fix,that is inexpensive,use instantly,easy to apply,seals well,lasts a while,get some thread sealant tape from your local hardware,you know the type?,for taps or gas fittings ,works well ,quick to apply,non sticky ,easy to remove, doesn’t, need knots,regards Firepony.