I saw in the kashering guide that countertops do not need to be kashered. My countertop is extremely absorbent and does not have a glossy finish on top. It was probably not installed correctly when I moved in. It’s like a kli cheres; if I spill grape juice on it, a purple stain will be left over.

Does this mean that my countertop needs to be kashered for pesach?

Also I was wondering why the guide says sinks don’t need to be kashered for pesach. Wouldn’t the chametz that got absorbed into the sink, like boiling pasta water that was drained in the sink, be problematic in some situations. For example if I would then use the sink to pour boiling water with vegetables into a colander, wouldn’t the steam that’s rising out of the sink and being absorbed into the vegetables contain the flavor of chametz?

Thank you