If you are losing the luster in the kiln, you can do the following: 1.) lower annealing temperature 20 degrees. Your beads will still be annealed. 2.) decrease the time at annealing temperature. 3.) Place a small ceramic or stainless steel container in the corner of your kiln. Fill partway with activated charcoal from an aquarium supply house. This will absorb excess oxygen, and help preserve the metallic luster.
There is a more information on LE thread below.
http://www.lampworketc.com/forums/showthread.php?t=171169&highlight=luster+charcoal
