Definitions for "Laid down"
A condition in which a print has been affixed to a mount to give it greater strength or to repair minor tears. A paper conservator may be required to remove the backing. "Laid to cardboard as issued" means that the artist or publisher intended the use of a support. See mounted.
Mounted to a blank. Sometimes used of detached leaves.
glued to a page
When something (illustration, engraving, map, etc) has been pasted onto another surface.
When a print has been pasted to paper, card, or canvas. A common practice before 1980.
Keywords:  stronger, backed, paper, material, see
backed with a stronger paper or material.