Always use the best quality materials available for mounting specimens. Since the lifetime of a specimen is nearly indefinite if properly stored, it only makes sense to use mounting materials (label paper, mounting paper, glue, etc.) which will not deteriorate over time and will last as long as the specimen.
If working on an ecological or anthropological project in which a reference herbarium is to be established, it is recommended that only good quality 100% rag mounting paper be used. It is better to store plants in newspaper than to mount them on poor quality paper. Never mount plants with scotch tape or other kinds of temporary tapes, and never staple plants to the mounting paper. Acid-free rag paper and permanent ink should be used for making labels.