I have no direct experience with doing trichrome stains on frozen muscle, but a quick histonet search turned up this wonderful post by Peggy Wenk:
Additionally she provides this great reference:
Good luck to you!
Teri Johnson, HT(ASCP)QIHC
Managing Director Histology Facility
Stowers Institute for Medical Research
1000 E. 50th St.
Kansas City, MO 64110
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