Lightproofing: Sticky advesive for slick plastic blackout sheeting

Probably last year, I asked about glues that would stick to the slick plastic blackout sheeting (white on one side, black on the other) that I use to black out my windows. Various helpful answers were offered. I've discovered another adhesive which I'll add for whomever may find it useful.

Just to note, my window solution uses easy-to-install and -remove, stiff foam insulating board about 1.5 inches (3.8 cm) thick. Wishing to save money at the time, I did not buy the kind with Mylar on one side, and despite spray painting the outer surface of the light-green stuff, it was hardly light-proof. So, I spray-glued the plastic sheeting on, white side facing the the room.

I had cut the board to be a bit smaller than the window opening, allowing the sheeting to overlap the edge by a couple of inches. I glued gray foam insulation (Frost King, 1-inch-thick strips cut from the 4-ft "cubic" lengths made for windows when room air-conditioners are used) to the edges of the insulation. The foam compresses to make a good seal, and it works well and easily. It's an old house with original windows, and I need to remove the panels when not in use in the winter especially, or condensation freezes and melts on the window panes.

After a year or so, the sheeting began peeling back in places from the insulation edges. Despite the sheeting overlap, light leaked. Various glues stuck to the porous foam but not the sheeting, at least, not for long.

I found a kind of caulk called Lexel, made by Sashco. It advertises "It sticks to almost anything, including itself." So far, it's doing a fine job of solving my problem.

Getting plastics to stick to anything for long is next to impossible, unless you use use special glues made by 3M or Loctite. For blacking out a window you can try 3/8 plywood painted black and then screwed to the window molding. For a light tight gasket around the plywood try using the loop side of velcro (industrial grade). Also you can buy light blocking fabric for various sources. I have made dove tailed wood panels that sit in the window frame with velcro-loop as a gasket; it has to be made very tight filling, and then screwed in. Any time I want to use the window I just remove the screws.

Mike

Ditto

and tinfoil

Not kidding

Others may join you -- dovetailed or not -- in screwing around with your window blockers. I have enough trouble measuring, let alone crafting something precise like that. Even if I had the tools, I'd be like a bad driver in a BMW -- capable car, unfit captain. Mine do the trick and (fairly) simply press in and out, thank goodness.

If it's polyethylene sheeting, Lexel won't hold. Nothing will. That's why all those glues and caulking compounds are sold in polyethylene tubes to begin with - it's inert to them! The two ways you can seal polyethylene is either to heat weld it together, or to use a special tape designed for poly sheeting. Neither is light-proof on their own. There are two kinds - ordinary red Builder's tape, and the far better but also far more expensive version of that made by 3M. Substitutes like Duct tape, Gaffer's tape, and even Gorilla tape will only temporarily hold.

If it's vinyl sheeting instead, Lexel will work. A basic acetone test will tell you. If the plastic is permanently hazed by an application of acetone, or even melted, then the sheeting is not polyethylene. The kind of thick velvety black roll stock I have does have a vinyl base, but it's black too, rather than white.

Generally it's better to wrap the sheeting around some kind of wooden frame and staple it in place, being careful that the staples aren't driven in so hard that the sheeting is punctured. Or else use tacks.

Incidentally, I always keep Lexel on hand. It was useful was emergency repairs to my asphalt roofing shingles after a bad wind storm last autumn, because it dries so much faster than ordinary roofing products - too fast for many cosmetic applications - little time to smooth it. It's basically more of a glue than a caulk. Several decades ago I got tired of having to constantly reapply seam sealant to my expedition tents, so switched to Lexel. That did the trick.

If you get luan plywood, which is 1/4 in thick, you can cut it with a utility knife. It is used for cabinets. Lowes/Home Depot carries it in 4x4 panels. You can also get them to cut plywood to size for you.
Buy black out curtains, black out fabric (used on movie sets) and nail it around the frame of the window.
Use an oversize piece of black plastic and tack it around the outside of the window frame.

Mike