Posted By:
andy beckerold mill and turkey red without frame are about the same value.....commons are about $200/ea.
turkey red with frame are tougher (especially if the frame is centered), but they do not sell for much more than the unframed tr's or old mills.
"A follow-up question...what percentage of white silks do you think are backed? I have been going to the Ft. Wash shows for the past 15 years and it seems like 75% or higher of white silks I have seen do not have backs."
the silly answer is ALL were issued with backs 
to answer your question, i would guess that less than 5% still have the backing attached, maybe as low as 1-2%.