I did some reading about Van Dyke printing on the web. In one place a 2 step toning were described, it took place (after the fix). First a Selenium toning and then afterwards a gold toning.

Can someone please explain what is the purpose of the selenium toning is in this case. Is it only used to reduce the overall contrast, or does it add some other value when used in combination with a gold toner?

Thanks in advance,