This rutile wash is 50/50 portions of rutile and gertsley borate. I use this as an over spray on my ash glazes. It makes great crystalline gold to rust blushing when I used it with my tenmoku.
I have also used it on my copper red glaze and depending on the thickness it makes a light blue to icy blue accent.
It is also great for brush work.
Since this is a wash, I would try it on any glaze at any temperature.