Light seal

[BJC0000]

Can anyone tell me the TYPE of foam used in camera seals?
I'm coming to the end of a home built 4x10 camera (over 2 years of part-time tinkering) and so far so good. BUT I'm trying to make a roll-film back to take 6x24 on the same camera.
The film back is sprung but I want to add a light seal around the 'red' window - may not even be needed but belt and braces....
Anyway I need a firm but compressible foam which will move and recover with the springs, about 50mm thick (there's a deep gap occupied by the springs between the back and the pressure plate) and don't have any idea about which type of foam I should even begin with. Any suggestions please?

 

[Dan Daniel]

The types fo foam used in camera seals vary depending on use. Open cell foam works in some places; close celled in others.

How much travel do you need in the foam? How compressible does it need to be? 50mm is getting to upholstery type foams. I suggest you start collecting any dark foam inserts in packaging and such; there is often nice foam used. Think of layers. Also if you don't need much compression, use something else solid for most of the opening seal with foam as the final layer?

 

[John Koehrer]

If you want thick foam try a hardware store for insulating foam. In the US I've found it around 1/2" thick

 

[Dan Daniel]

If you want thick foam try a hardware store for insulating foam. In the US I've found it around 1/2" thick

Reminds me, there is a thick foam seal sold for window air conditioners. It is dark gray, maybe 2 inch by 2 inch by 2-3 feet. This is the right season to find them in hardware stores.

 

[BJC0000]

Thanks for those replies.
Dan, yes I've considered layers . I've now decided to remake the back without springs (I'm no engineer and making springs was difficult and inaccurate) and just use foam as a compressor for the pressure plate.
Foam should be easier to adjust and coupled with a rigid layer more stable - also easy to replace.
What I was really interested in was the type of foam - there appears to be at least 6 types commonly mentioned -
Chloroprene / Neoprene (CR)
Neoprene / EDPM Blended
Natural Rubber (NR) - Open Cell Type
EPDM
PVC / Nitrile
Vinyl / Nitrile
and I wondered if any of these was more suitable (or useless)?
More experimentation needed I think.

 

[Dan Daniel]

I don't have contact info, but John Goodman makes foam seal kits for cameras. I know that he uses specific types. If you can find him, send him an email and see if he can help direct you to the right type?

 

[MattKing]

Jon (not John) Goodman and I have corresponded in the past using JGood21967@aol.com