Xuan paper couplets can be trusted
In this case, they are mostly the works of celebrities or calligraphers.
Ketuo is a special term for mounting paintings. It means that this is a "rice paper" work, it has preservation value, and you can give it a try.
Generally, good works of calligraphy and painting are done on 'rice paper'. Finally, a seal must be stamped. The ink pads used for seals are oily mixtures containing special colored substances. These special materials will slowly 'immerse' into the rice paper through external forces (including stacking of books) and slowly spread. Regardless of whether this work is folded or stored in a "paper barrel", any part that comes into contact with the seal will be "soaked" and contaminated by it. It ruins the beauty of the entire work. The only way to preserve it is to simply 'hold' it before mounting. That is to say, use non-expensive paper materials to 'support' the calligraphy and painting underneath. This way, the problem of associated contamination is solved. This is just a way to prevent stamp contamination. In fact, real painters and calligraphers also protect the paper of their works from moisture and mildew during storage. This ‘support’ does not affect re-mounting.
In addition, it is easy to watch by holding it up, and you can stand it up temporarily for viewing.