Lightproofing larger commercial windows

[Dante_Stella]

For a darkroom I am constructing, I need to lightproof some commercial aluminum windows that are 5x8 feet (w x h). By commercial, I mean double-pane glass in box aluminum frames. They butt into a corner, one panel on the left, two on the right. 8" cement sill below, little cement lip above (and then several feet of wall to the ceiling).

The goal here is to allow the windows to let in light on demand but be lightproof when needed. Lab-grade blinds are about $2K. Lab-grade blackout curtains are about a grand. A huge quantity of black foamcore is not very much money but might present some engineering issues with opening. Ikea makes some fairly inexepensive blackout roller blinds that don't have side pockets (and may or may not really be opaque) - but may be a good raw material source.

What's your best shot? This is in a climate where the glass and frames will be quite cold a couple months a year.

Thanks!
Dante

 

[mdarnton]

I think your big problem is trying to build a darkroom that doesn't stay dark. 🙂 Have you considered something like being satisfied with less than a full opening window cover? If I were in your situation, I'd do something like cover the whole thing with foamcore, and then cut a window somewhere in the foamcore, and build a light-proof door for that, which would be relatively easy.

I bet that no matter what you do, condensation on the inside of the window is going to be a problem, so I wouldn't attach anything directly to the glass, and might also provide some sort of light-trapped airflow.

 

[Vince Lupo]

I did a show a number of years ago that involved blacking out a series of much larger windows than what you have (like 12ft x 14ft each and I think there were 5 in total), and I used black Savage background paper. Now, the way I did it, you couldn't open and close them at will, but maybe you could engineer a hanging/roller arrangement for black paper.

Another thought would be to find some black stage curtains from a theatrical supply house - they would definitely black things out.

 

[Joakim Målare]

If you go for the Ikea roller curtains, buy enough for two layers. I have one Ikea roller within the window frame and a different kind on the wall that covers a lot more than the window. They work best as is - if you cut them down and try to sew pieces together, beware of small holes where the stitches go. The material is rather hard and don't allow for folding. Creases end up letting light through after a while.

I went to the fabric store and asked for light-tight material. They let me check a few sorts and the one I got is great. Nothing special but quite heavy.

I can tell you that I am still not satisfied.

We are looking for our next place to live and when we get there I will definitely set up a darkroom that is always dark. Windows will cause more problems than joy, if you intend to use the room for printing more than very rarely.

 

[Lflex]

If I understand correctly, you have 3x 5 by 8 feet windows to cover? If so, I would go for the 1K curtains and get over with it.
In my past, I worked at an art museum and on occasions we had to lightproof rooms using some very effective material intended for theatrical productions - yet it was always a pain. I can only imagine the nightmare it would be to make it an effective dayligt on demand solution.

 

[Joakim Målare]

Another thought would be to find some black stage curtains from a theatrical supply house - they would definitely black things out.

I think I made my custom ones from something similar, although I don't know the name for that sort of fabric. It's black, dense and two layers, that's all.

You'd be surprised to see how easily light is reflected around corners, finding its way into darkness. In my opinion it's not worth the hassle trying to hang fabric or using rollers. One thing that could work would be a sliding cover, tightly fit into a light trap. Sort of like a large scale shutter curtain I guess. But it would take some work to make one that functions well and looks good too, which I suppose would be desirable when the room is filled with daylight...

 

[mdarnton]

If money is more of a concern than classiness and tape residue, I did once work in a commercial darkroom that had the windows closed with thick black construction plastic and black masking tape. I've done that in subsequent darkrooms of my own. Then you could still rig up a "door" in that, as I mentioned in my first post

 

[Dante_Stella]

If money is more of a concern than classiness and tape residue, I did once work in a commercial darkroom that had the windows closed with thick black construction plastic and black masking tape. I've done that in subsequent darkrooms of my own. Then you could still rig up a "door" in that, as I mentioned in my first post

We're always trying to keep it classy 🙂 - but at the same time, it's hard to amortize a $2,000 expense on a two-year lifespan for a property you don't own. The black plastic sheeting (which I have used before on smaller windows) definitely seems to be available at construction and, ahem, hydroponic gardening shops, but it will probably end up being a curtain. The space is very airy and luminous for things like matting and framing, but there's the rub, I guess.

Dante

 

[Dante_Stella]

If you go for the Ikea roller curtains, buy enough for two layers.

Thanks Joakim - is the problem that the material is not really lightproof? I was thinking about using the material only.

Dante

 

[Joakim Målare]

Thanks Joakim - is the problem that the material is not really lightproof? I was thinking about using the material only.

Dante

It is lightproof. My phrasing was a little off when I mentioned two layers - I don't stack the curtains closely. I have one curtain inside the cutout in the wall that takes away the most intense lighting, so that the light sneaking around the second curtain that covers most of the wall, is minimized.

I would recommend buying a black, dense type of cloth (also lightproof) from the fabric shop if you want to sew your own curtains. The Ikea roller material is a little stiff and doesn't "heal" well around the stitches. I also believe you get more for your money if you buy sheet/roll material in the first place rather than a ready-made product that you sort of throw away.

That's my opinion, but I did exactly what you are about to do, so I know what I would have done differently.

Good luck!

 

[Dante_Stella]

Thanks Joakim!

Also, I did locate this, which is lightproof heavy vinyl material prefabbed with velcro tape on the back. Not light-on-demand, but fairly simple - and the velcro is supposedly good for 2.5K openings/closings. Not as cheap as some other solutions, but I suppose there is no waste when you botch an 8' long cut.

http://www.blackoutez.com/Custom-Sizes/Custom-Blackout-EZ-Window-Cover

Dante

 

[Morry Katz]

Glue velcro ribbon to the window frame and the perimeter of the heavy plastic sheeting which has been cut to fit the window. It's a bit of a fiddle to put up and take down but it does work.

 

[PRJ]

Dante, if I faced that situation I would build a frame around the windows and then attach masonite to it. You can use photolith to make a safe light out of a hole or two, or to be able to look outside, but I wouldn't do that if it would be in direct sun. It is nice to be able to see the world outside when printing long hours. You could figure out a way to let light in with a hole in the masonite as well. I would build a frame around the hole and route it so a piece of masonite would slide in, or put it on a hinge. There are many ways to do it. You could also make a window cover out of foam core and gaffers tape (real gaffer's tape).

I have been in a lot of darkrooms in my life. Curtains are the last thing you want (dust, and bulky). Blackout plastic is pretty cheap but it should be doubled up and there is always a problem of sealing it at the edges. It never stays sealed and I don't think it would work as a barrier against the outside world very well, especially in direct sunlight over an area that large. It also has no structural integrity. Velcro would leak light if you used it.

I would encourage you to do it right and not try to mickey mouse it. If you are not comfortable doing it yourself, hire a carpenter to do it for you. It will still cost you far less than $1000.

 

[drewbarb]

I have two 3.5'x7' windows in the room I use as my darkroom. I used heavy theatre curtain material and a couple of 4'x8' sheets of masonite and some 1"x lumber to block the windows in such a way that they are totally light tight but I can open them in a couple of minutes. The way I did it hinges on the fact that they windows are set into sills that are about 6 inches deep. I cut the masonite to be a few millimeters smaller in every dimension than the openings. I covered these with the fabric leaving a few inches overhanging in every dimension. The material is very thick and heavy, and almost (though not quite) light tight by itself. The fabric-covered panels are simply pressed into the openings, and friction holds them in place. I have a few pieces of 1"x1" cut to the full height of the openings that I brace in to help hold them in place- though in truth they aren't really required. I can pull the whole thing out of each window in a few seconds, and press them back in just as easily. They are a bit ungainly being so big, but I can pop them in or pull them out in a couple of minutes anytime I need to. Total cost for the fabric, wood and masonite was under $200; took me a couple of hours to do the measuring and cutting.

 

[Gabriel M.A.]

What's your best shot? This is in a climate where the glass and frames will be quite cold a couple months a year.

Other than custom-making a frame around them where you could literally slide over black vinyl (in a slide-in a la sheet film fashion) or similarly truly opaque material, I can't think of anything else you haven't mentioned.

Good luck!

 

[Dante_Stella]

Patrickjames, we used masonite last time, screwed into wood windowframes with black weatherstripping to seal the edge. Getting sunlight was easy; we just opened the back door of the rented space 🙂. This new space poses a challenge because the only door faces an unlit interior hallway. On the velcro issue, wouldn't 3/4" black stips be lightproof?

Dante

 

[Joakim Målare]

I had the idea of sewing magnetic bands into the curtain. I figured I could hang the curtain as usual, and have the magnets attract to the iron paint that I used around the window.

The magnet bands were not strong enough and the paint was probably too thin, but I still think it's a fairly good idea.

But velcro is probably easier.

 

[Dante_Stella]

I just enlisted the aid of my sister, a mechanical engineer who builds theatrical sets... We'll see what she says. I hope that when it is done, I can do some wire work in there. 🙂

Dante