i think it's ok, if you bleach and/or physan them to clean them. bleach works really well, and i have actually soaked live orchids in bleach, pot and all to (finally) kill off a mold in a Lealiocattleya, with no ill effects. i have used bleach and physan in bark mixes, treefern and cork bark so far. if insects may be an issue, you can also freeze mounts for a few days, thaw them out and use them. i learned this trick to cure imported african artwork to get rid of creepy-crawlies living in the wood.