I have not used the iron off type but I use the blue colored pounce powder. It shows up on every color I've tried it on. You can also use a black light that will help it to show up on lite colors.
When you first start using a new pounce pad it you need to "load" the pad w/chalk. It takes a while to get the chalk into the pad. When I went to LA class they used it and pounded it to make sure the chalk is in the pad, then using the eraser method works, rather than actually "pouncing" it. I live on a bumpy dirt road so I put mine on the floor of my Jeep for a few weeks to bounce the pounce into the pad.
Hope this helps.
Marie