Protect a Retirement Poster for Sign-Off?

Let’s say you’re having a retirement party, and you have a poster-size photo for people to sign in the margins. But, there’s always a wise guy who’ll draw a mustache on the face, etc. How can you protect the face without hurting the picture?

Saran Wrap comes to mind, but what else might work?

When I make these for clients (I own a frame shop) I put a sheet of clear mylar or acetate over the photo.

You can get sheets of acetate from an art supply shop that sells drafting supplies (I imagine - it can’t all be CAD now, can it?)

How do you attach a sheet of acetate or mylar without damage to the picture or poster?

I worked for the gov’t for 37 years, and the standard retirement or going-away signed picture was always the official photo of the facility. I’ve never known anyone to do anything to the picture itself - signatures always went on the mat. Defacing a photo is pretty classless, IMHO.

I work and an art supply store with a framing department. We certainly still sell rolls and sheets of acetate and Mylar. In framing, we do plenty of exposed mats with acetate over the photo, too.

If you want signatures on the picture itself, just not in the middle, I think a sheet of static window film might cling to a glossy, mounted picture. Maybe use silicone glue in super-tiny dots to hold a sheet of plastic over a part of the image, but that may still result in a more visible mark than just trusting the signors maturity. (Perhaps limit the available time to sign it to before drinks are served?)

Too late to edit…

Scratch the silicone glue, use Scotch removeable clear mounting squares if you want to hold a thin sheet of plastic over it and you don’t mind the protection being somewhat visible.

I’m sorry - I altered the OP in my head to match my own experience. What I typically make is a window mat with a large (4" - 6")margin. The photo is mounted onto a backing board and the mylar is taped to the back of the window mat.