HI All--

I'm looking for a US supplier for chromium powder to use in H-device.  
Thermo supplied us with 500 micron, 99.9% chromium originally--though 
the service manual has it as 150 um.  Does size matter?  Alfa Aesar had 
a -48 mesh (less than ~350 micron), 99.95% pure powder, but not any 
more.  Has anyone tried the 100 mesh (~150 um), 99% pure stuff that's 
more common?

Thanks in advance.

take care

gerry