Hanging very large, unframed watercolors

[Robbain]

We recently hung four large (approx. 7'x10') watercolors. The artist wanted them hung with only one nail in each of the top corners. (I know...) To do this I laminated squares of #300 watercolor paper to the back of each corner with PVA adhesive. These held the weight, but as the paper has moved (expand/contract) due to our imperfect climate control the paper is very slightly tearing- but it's tearing left-right, not down. I tried replacing the nails with linen-lined binder clips but they are not strong enough to hold the weight, so I don't think RE magnets will cut it either.
What other options are there short of putting more nails through the top edge? Is there a material I should've used besides the #300 paper?

[Mark Wamaling]

I seen people secure metal plates (behind the piece) on the wall and then use small super magnets on the face of the work to connect to the wall. Not sure if this is a doable option for works this size?

[Robbain]

I seen people secure metal plates (behind the piece) on the wall and then use small super magnets on the face of the work to connect to the wall. Not sure if this is a doable option for works this size?
I've used those Rare Earth Magnets in the past- I think the paper would be too heavy for them. At the moment we're using the original nails in the corners, plus several binder clips across the top, as a stop-gap.

[Paul Abbey]

I have also used rare earth magnets in this way.. Fender washers screwed to wall or drywall screws drilled flush to the wall, flat rare earth magnets taped to wall ( if only for a short time). Normally Use between 3/16" and 3/4" disks on the face of the paper. Always with buffer appropriate to surface--tyvek tape, artist's tape, archival papers work also. If the surface of the paper is quite delicate, careful of the strength of the magnet used. They will burnish the surface if too strong.

[Jamie Hascall]

We used magnets in a little different way. We would embed the magnets in the surface that the art was to be mounted to, and would put a strip of felt over them all to provide a buffering surface and promote friction hold. A strip of fairly stiff (16 gauge) sheet metal backed with the same felt and painted to an appropriate color, would them be placed on top of the magnets with the art between the layers. In this way, the level of hold was more consistent, and visually, the strip was a less obtrusive element than the individual magnets. The strip is also much easier to safely remove at de-installation.

We were using this on textiles which had a tendency to scallop with single points of support. I'm not sure if this will have sufficient strength to support your paper works, but number of magnets and choice of padding material will determine much of that.

Good luck.
Jamie