Wallpaper, Off-Gassing, and a Lesson in Science

IMG_2550Here is a textured and patterned heavy vinyl wallpaper on a non-woven backing that I put on the back of a set of bookshelves in the home of a young family in Bellaire. The interior designer was Pamela O’Brien, of Pamela Hope Designs.

I did have some problems with bubbles developing in the material, but I smoothed them out, and everything was fine when I finished. But … a couple of weeks later, the designer’s secretary called to let me know that more bubbles had developed. I went over to the home today, to do what I could do to get rid of the bubbles.

Bubbles like this are caused by “off-gassing,” which means that, as the paste dries and moisture evaporates, air gets trapped between the thick, impermeable vinyl wallcovering and the wall, which in this case was probably wood painted with an enamel or schellac based paint (as opposed to drywall coated with latex paint), with my primer on top of that. In other words, no where for the air to go. So all those air molecules gathered together and pushed up bubbles under the wallpaper.

The representative from the wallpaper company said this in his reply to me, “I think you are right. The surface you hung on looks like an enameled coated wood or particle board. In either case the surface could not absorb moisture, as regular wallboard would, so the moisture would have no where to go, being that the vinyl is impervious. Putting on wall liner might have given enough air space to circulate and dry. Bookcases are very hard to hang anything on because binding to a hard surface is always difficult and all the more with a commercial vinyl.
“The vinyl is now formulated so there is very little off-gassing, and what there is comes off the front.”

OK, it’s good to know they are aware of the problem, and have developed a solution – a paper that “breathes” so as to allow the air to escape from the surface, rather than the back. But that didn’t help me much, since I still had to deal with this older version of the product, which was off-gassing from the back, and bubbling!

I revisited the home today, almost a month after I originally hung the paper. A few bubbles were visible. (I suspect that some evaporated and flattened out during preceeding weeks.) I was surprised to see that there was still a lot of wet paste under the paper, yes, even four weeks after it hand been hung. With a solid wall surface behind it, and a solid vinyl surface on front, there was simply no where for the moisture to go.

I was very happy that, for almost all of the bubbles, all I needed to do was prick a tiny hole and then push the air out. Since the paste was still active, the vinyl quickly stuck to the wall behind it. There was only one area where I had to cut a small slit in the paper and work some adhesive behind.

When I left, it was all nice and flat, and it looked great.

I do love it when I can get a little science lesson along with my wallpaper projects!

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