1)when kashering a sink (or utensil) is it obligatory to first clean the sink before starting to wait the required 24 hours or can one first start the 24 hour clock and only then clean the sink (before doing hagalah of course)
2) when using a kettle or a pot to kasher the sink does one have to make sure its still on a rolling boil when pouring as very often it stops boiling as soon as you take it off the fire
- You do not have to wait 24 hours from when it was cleaned, rather from when it was used last for hot things.
- Under the assumption that you don’t put your hot chometz pots directly in the sink when they are hot then the sink only need to be koshered with a heat of “iruy kli rishon. Pouring from the kettle even though it is no longer bubbling is still considered iruy kli rishon.