Recommended light-tight materials for camera construction?

[Failagogy]

I am making a film holder for 14x17" film and would appreciate suggestions for light-tight materials for the darkslide and back. Aluminum works, but it's expensive; garolite and ABS sheets have been reported as unacceptably translucent. Quality 1/8" birch ply is perhaps an option?

As for the rest of it, are any 3D filaments unsuitable? I was looking to join together smaller prints to form the slides around the edges, bound by a steel strip.

[Tin Can]

Waste of time unless you make the film/focal plane match the camera

3d prints are lumpy and DS will not be easy to use

Go to Home Depot and find THIN sheets of aluminm cheap

24X36" $20

The trick is cutting it

[jp]

it may be worth the investment to buy a working 14x17 holder and build the camera back to work with it. They seem to sell for $3xx on ebay. The good film isn't cheap and worth taking care of while out of the darkroom.

I have also used protostar ultra black flock sheet on homemade lensboards,lens barrels, and such for light-tighting material. it's not cheap, but it's just cut to shape and stick on , and it lasts well. You really don't need much.
https://www.fpi-protostar.com/hitack.htm

[Drew Wiley]

There are all kinds of Garolite phenolic, some of it totally black; it's problem is that it can warp with significant humidity changes. The darkslides in my older Lisco and Fidelity holder are thin stiff black ABS; the newer ones, a more flexible Sintra-like plastic. My Mido holders use a thin PC board material. Clean cutting of thin aluminum requires special equipment. Don't go with hobby plys; their thickness can vary either with mfg quality control or humidity. Search McMaster for appropriate sheet goods, like thin STIFF PC board material. I can't imagine any kind of Cheao Depot aluminum staying flat. McMaster gives real industrial specifications for everything of that nature they offer.

What kind of shop machinery do you have? That's crucial. Otherwise, if you do choose aluminum, have a real sheet metal shop cut and edge it precisely to the size you need, and explain that it needs to be an alloy which remains totally flat. Working with a rail saw, panel saw, mitre saw, or table saw requires the correct non-ferrous blades for either thin aluminum or thin stiff plastic. Those correct carbide blades don't come cheap. An ordinary plywood cutting blade will leave a bad edge, and could be downright hazardous. And ideally, you place your thin material in a sandwich of softer thicker material when cutting, unless you are specially equipped to do otherwise. Need the right clamps too. I've seen quite a few serious accidents when people took shortcuts - lost fingers, hands, eyes.

Plastics stores will cut the products they sell to precise size with a modest surcharge; that's where I'd start. Thin black Sintra can be cut using a matcutter, print trimmer, or even box knife and straightedge.

[Failagogy]

it may be worth the investment to buy a working 14x17 holder and build the camera back to work with it. They seem to sell for $3xx on ebay. The good film isn't cheap and worth taking care of while out of the darkroom.

I'm not shooting good film; I'm shooting X-ray film and making press prints. I don't even own a scanner.

I have also used protostar ultra black flock sheet on homemade lensboards,lens barrels, and such for light-tighting material. it's not cheap, but it's just cut to shape and stick on , and it lasts well. You really don't need much.
https://www.fpi-protostar.com/hitack.htm

Using a layer of the stuff on the inside of a darkslide isn't a bad idea. I've also thought about laminating metallized mylar (aka "space blankets") or even aluminum foil inside other materials to increase their opacity.

The darkslides in my older Lisco and Fidelity holder are thin stiff black ABS; the newer ones, a more flexible Sintra-like plastic.

Any ideas on purchasing something similar? There seems to be a lot of variation in the opacity of ABS. Foamed PVC (aka Sintra) sounds like a great solution, especially given 1/4" sintra weighs less than 1/8" aluminum and won't bend as easily.

What kind of shop machinery do you have?

University art shop, so quite a bit assuming someone hasn't broken it. There's a giant guillotine cutter for sheet steel, and I can square the edges with a file. And, of course, my favorite tool: the laser cutter. There's even a waterjet somewhere on campus.

Thin black Sintra can be cut using a matcutter, print trimmer, or even box knife and straightedge.

That sounds like a huge win. Any thoughts on the opacity of it?

[Tin Can]

Just sent you a PM

I have 2 NOS 14X17 holders FS in our FS section

X-Ray fits perfectly

[Greg]

I once posted:
"For a while I used Medical 11x14 holders with the spacers on each side removed and screw holes filled in (not necessary). At a State Surplus store connected to our State's Medical Center, Hospital, and Medical school I used to find them every now and then for way under $50.00 each. They also sometimes had 14x17 holders for sale at the same price or for some? reason for less money. All were obviously in used condition but light tight and served me well for years. Best find was once when I found four 14x17 holders that were not priced. Asked how much, and the person at the check out counter told me they had been put out for sale for months with no takers. "just take them they're yours"!!!"

[Rick A]

I used aluminum flashing from the hardware for my dark slide, it comes in different widths. It usually has white on both sides or brown and white on either side and can be painted.

[jimskelton]

I made double sided 8x10 film holders, using softwood for the edges that contain the darkslide grooves (cut by table saw) and 1/2" plywood for the body, though I'm thinking 3/8" would work as well. I just used black matt board (used for mounting pictures) as the dark slide. It's has a non standard film plane offset, so I had to make a matching ground glass, but it works well with paper negatives. When evaluating materials for a dark slide, I got the most powerful light I could get and put it up against the candidate material in a dark room to see whether it let in any light. For smaller dark slides, I found some nylon/plastic folder covers keep out light, but that would be too flimsy for 14x17...

Black PLA filament is pretty light tight starting at layer 4, and completely light tight by layer 6, which is around 1.2mm. But I found anything with seams have a tendency to hang up when inserted/removed from the film holder, and joining the seams in a light tight fashion can be a challenge. And, 14x17" worth of PLA is quite a bit of PLA!

[nolindan]

garolite and ABS sheets have been reported as unacceptably translucent.

Black garolite is perfectly opaque.