Fully protected? Not at all.
I have seen prints done with the best Vivera gray inks on Canson Rag Photo turn brown when shown in a restaurant gallery for a couple of months with no plexi and also pinned on the wall of an art department office. They were all sprayed with three coats on the front with the Hahnemuhle uv spray. The same prints in a portfolio were not changed at all.
There are so many kinds of pollutants floating around that we can’t detect, such as from air conditioners, heaters, cleaning chemicals, autos, etc,etc, that we are just beginning to learn about.
I’m not against people mounting to dibond with a cold adhesive , spraying the front with the solvent uv sprays and showing briefly in a gallery. I’ve printed shows shown that way, but you are taking a risk, so just beware, and never ever let the gallery sell them to hang permanently that way. These receptor coatings are magnets for all toxins. Rc papers are a little better protected, but I personally would never recommend hanging one of those without plexi for very long either. Just because you have not had issues doing this doesn’t mean it’s safe.
I wish it was as easy to spray these prints with a good canvas acrylic latex varnish like Timeless, or have them laminated with a satin laminating material, but that just destroys the dmax and surface of the print. If you are going to do that you might as well print on plastic paper because that’s what they look like. I’ve tried it many times.
Believe me we will be hearing a lot more about this in the future. Wilhelms “ bare bulb” years of display figure are a joke in my opinion. It all depends on the particular location the work is being hung in, and that varies widely!
I would much rather frame a print with the plexi touching the face of the print in a show than leaving them naked with just the spray.
John
Microporous paper prints can easily be sprayed with Moab, Hahnemuhle or Premier Art spray and be fully protected from atmospheric pollutants.