Material for septum and darkslide in DIY holder - UK (not Garolite)

This is an old chestnut but I'm wondering if someone can help me out from a UK/EU perspective.

I'm thinking of a 4"x10" camera project with my own design of holders. I need a material for the septum (somewhat ridge) and dark slides. Most discussions talk about using garolite xx from McMasters. I can't see this stuff available in the UK or EU. I think it is a US trademark thing or possibly full of deadly chemicals!

What is the equivalent outside the US and where would I get it?

I'm looking at ordering ABS and PVC sheets off eBay shipped from China which look good but until I have them in hand I don't know.

I presume 1mm ABS sheets as stiffer and suitable for both septum and dark slides?

Any experience with this?

My first impulse would be to drive to my local hardware store and pick up some 1mm sheets of aluminum or sheet metal, then paint those matte black. The sheet metal will be sturdier but much heavier. The aluminum would warp more easily but could be laminated with some kind of plastic to make it a little less pliable.

Garolite is an umbrella term for fiberglass composite sheets. FR4 is probably the most common variety of it and is used for manufacturing printed circuit boards, G10 is afaik the same material without the flame retardants.

I don't know if there's an equivalent term in the UK but looking for epoxy glass laminate or phenolic glass laminate should get you pretty similar stuff.

thinkbrown said:

FR4 is probably the most common variety of it and is used for manufacturing printer circuit boards

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Interesting thought! This makes it available copper-clad, which is perfectly opaque. I think >10" lengths should be available as well, although 100x160mm is a more common size. Should be available from any electronics components distributor and of course AliE.

koraks said:

My first impulse would be to drive to my local hardware store and pick up some 1mm sheets of aluminum or sheet metal, then paint those matte black. The sheet metal will be sturdier but much heavier. The aluminum would warp more easily but could be laminated with some kind of plastic to make it a little less pliable.

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I thought about aluminium but I'm trying to make it as light as possible and painting the septum would be an extra complexity. It is an option though.

koraks said:

Interesting thought! This makes it available copper-clad, which is perfectly opaque. I think >10" lengths should be available as well, although 100x160mm is a more common size. Should be available from any electronics components distributor and of course AliE.

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They also make versions that use a black epoxy, though I'm uncertain how lightproof that is.

koraks said:

Interesting thought! This makes it available copper-clad, which is perfectly opaque. I think >10" lengths should be available as well, although 100x160mm is a more common size. Should be available from any electronics components distributor and of course AliE.

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Ah copper clad! Looking at what was on offer I was thinking FP4 or possibly G10 but they all seemed translucent and painting would be a pain and unreliable.

thinkbrown said:

They also make versions that use a black epoxy, though I'm uncertain how lightproof that is.

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Yeah I saw one supplier on eBay but only one size and I'd be worried about how opaque of if they would be available if I went back for more.

I have spent ALL Sunday morning and 4 cups of coffee on this now! It is paralysis through analysis. I think I might order some black ABS and see how stiff and opaque it is. It seems to be readily available, cheap and light. The question is how stiff it is (@ 2mm for the septum) and opaque it is (@ 1mm for the slides). It will be a cheap mistake if it is a mistake and I'm sure I'll find some other use for the material.

Now outside for some fresh air - maybe with a camera in pocket.

What about carbon fiber sheets?

A bit off-base but when I needed some 6x9 dark slides for holders missing them, I found some 4x5 dark slides at a good price and cut them down.

RogerHyam said:

Ah copper clad! Looking at what was on offer I was thinking FP4 or possibly G10 but they all seemed translucent and painting would be a pain and unreliable.

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The FP4 stuff should work fine. Btw, it comes in various thicknesses. Default is 1.6mm, but thinner is also available. I don't know about anything thicker, but I doubt you'd need that for this application.
Here's one I could quickly find on AliE for the 1.6mm material in a size that allows you to take 4x10" from it (sadly, at 200mm it's *just* too narrow to make two actual 4x10's): https://www.aliexpress.com/item/1735548546.html