Saevetei is pretty tolerant of answering questions. Many are answered. Specifics are explained.

Apparently all of the chalk can pull from other chalk, gold's just notable because it's lossless. She explains some more details of exactly what she's doing for the ritual, and upon running out of jargon that will make sense to Grendyne, she somewhat wryly offers to let Grendyne try just draining a single item through chalk just to get a feel for how it works, not to do anything at all.

Then she recalls that Grendyne probably needs a demonstration first. Would she like one? The ritual is ready, anyway.