from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Rising
- n. The medium used for mounting a slide
- n. The adhesive used to affix a photograph to a mount
from the GNU version of the Collaborative International Dictionary of English
- adj. Raised; high.
from The Century Dictionary and Cyclopedia
- High; raised: a quasi-heraldic epithet.
- n. In photography, a paste or other adhesive substance used in mounting prints.
mount + -ant (Wiktionary)
The mountant has since been yellowing and turning opaque.
Aside from the glue mountant, formula for which accompanies the paper, I know no preventive except to mount the prints while dry with the dry mounting tissue.