Wallpaper that will block surveillance and protect against EMP
This idea sounds great but the cost of course is always the rub.
In place of that here are a few other ideas you might consider, not proven, but plausible and likely workable to some extent. Just use your common sense and some testing to see if it works.
First off is the old Microwave method. I’d cut the cord on it, unplug it first please – Duh
Even without that you may get some level of RF energy protection just by putting whatever electronics you have inside it. If the microwave is designed to stop HF Radio Energy from leaking out then it makes sense that it should stop it from coming in as well. Since the size is so mall I’d save it for USB memory sticks and back-up drives, maybe some cell phones out of use, and a portable laptop not in use either.
Aluminum Foil Closet
I wouldn’t go through the effort to foil wrap a whole room but a cabinet or a closet foil wrapped from the inside with foil tape connecting it may give you some element of protection from RF energy. Those foil bags used to ship memory chips or toll devices have the common word foil as in aluminum. If you can’t get a signal in or out then some at least minimal level of protection exists.
All steel surplus ammo cans also serve as a fallback hasty EMP protection. How about just burying it in the dirt, but separate it from the ground by wrapping it in plastic or putting it in a sealed plastic cooler, sealed with silicone caulk. Put plastic trash bags around the can and you might add another layer of element protection by limiting water exposure and galvanic action on the steel cans. It will take years for the elements to penetrate. Based on tests a new painted can could last over a decade without penetration by rust even when sitting directly in the dirt. Put any items inside the can in waterproof Mylar bags for double protection and and you have a reasonable expectation of EMP protection along with physical security from theft or seizure.
If it is a photographic image you want to save there is always an option to print a paper copy and store it in a fire resistant safe. One of those document boxes might make sense. EMP won’t then be a worry, but instead heat and theft, or worse yet, water. Water destroys more paper, wood, and metal products than probably anything else. Keep it dry.
This is your final protection. Have multiple copies or devices in various locations with as much protection afforded those as you can arrange. An off site storage in the cloud may even survive if the service has taken the proper steps. All of these efforts are suggested to improve your outcome, save your data, and have electronic devices survive an EMP attack.
Disclaimer: These are just ideas for thought and some have not been proven or tried so the whole discussion here is for informational purposes only. Any ideas discussed are only to help you brainstorm for protection ideas against SUN EMP events or other more insidious human actions to destroy electronics and data.