Use heavy, archive grade, acid free paper. Most herbaria use a standard size of 11.5" by 16.5" for mounting specimens. This paper stock is traditionally a linen based paper also known as “Rag”.
Leaves and smaller stems can be glued to the paper using PPA glue (archive grade). Simply brush a light coat of glue onto the leaf or other material and then apply to the paper. Press while the glue cures.
Heavier material such as bark or stem sections are applied using strips of linen cloth which have been soaked in PPA glue. The strips are then placed over the thick items with enough length to securely adhere to the paper on each side.
For leaves that have been dried but not pressed you can soften them up by wrapping in a damp towel. This will restore pliability. After this you should press them nice and flat. Leaves can be pressed between the pages of a large book or placed between sheets of newsprint and stacked between books or other heavy items. Press until the material is fully dry and then it is ready for mounting.
Properly dried material is very stable and needs only to be kept in a humidity controlled environment (low humidity to prevent mold). If you use Air Conditioning in hot weather and heat in cool weather then your home environment is usually adequate.
If you ever require further information or have any other questions regarding the preparation, preservation or presentation of herbaria specimens please do not hesitate to contact us anytime!