Hi and welcome
You don't want to use anything that gives off it's sap, like pine. Cypress seems to work best
What types of orchids are in the collection? Which are you planning on mounting? We'd love to see some pictures
...and if you have a spare moment, you might want to leave an introduction in our Introductions-Break The Ice forum. It's not necessary but I'm sure the rest of your new friends would like to say
