Ceramic fiber blanket redundant?

If the heat riser is one the vacuum formed ceramic fiber heat riser described on Brian Kopp's thread, is a ceramic blanket still necessary, or not necessary but still a good thing, or completely useless?  

If I'm going to use one I should order it now as I have most everything else.  

Thanks rmh experts for your help.  

Hi Susana,
Those risers are made for pouring molten metals. I don't plan on using a layer of ceramic blanket insulation with it. Neither does Peter nor Matt Walker use one to the best of my knowledge. Any other input is welcome.
Brian

Great!  That simplifies my plan.

And thanks again for coordinating that purchase, Brian.