Source for phase box board

I need a source for lig-free phase box board that is larger than
what I have been able to find. 54" x 60".  Does anyone kow of a
source for the board in 4' x 8' sheets?

Ramona Duncan-Huse
Head of Conservation
Indiana Historical Society
450 W. Ohio Street
Indianapolis IN 46202
317-234-0093

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                  Conservation DistList Instance 13:28
                 Distributed: Tuesday, November 2, 1999
                       Message Id: cdl-13-28-025
                                  ***