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Thread: mounting gelatine filters between glass

  1. #1

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    mounting gelatine filters between glass

    I need new filters for my tricolor cameras. I have now found a place that can sell me the right gelatine filters. Only problem is that they cannot mount them between glass. I took apart one of the defective filters and can get the old gelatine out. Still need to see if I can clean it well enough.

    The lady I had at the phone told me that they mount it between 2 plates with spacers in order to avoid Newton rings. Only thing is that I don't have spacers in the original filters. Also the glass is much thinner than what they use (they use 2mm while the originals are 1.4mm). So the plan now is to re-use the old glass.

    But how do you mount those gelatine filters between 2 glass plates? The old ones were glued over the complete surface. I really have no idea what glue to use and even less of a clue how to do this without bubbles. Does anyone has an old book that describes how to do this?
    Expert in non-working solutions.

  2. #2
    Tin Can's Avatar
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    Re: mounting gelatine filters between glass

    Maybe the glue was thinned Canadian balsam

    http://adsabs.harvard.edu/full/1972AASPB...5...15S
    Tin Can

  3. #3
    Tin Can's Avatar
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    Re: mounting gelatine filters between glass

    I have been buying a lot of this glass. 0.063" as measured right now, its very nice, smoothed edges, other sizes available, but bigger may be thicker

    https://www.amazon.com/MCS-Format-Fr...%2C174&sr=8-28
    Last edited by Tin Can; 28-Oct-2020 at 14:34. Reason: corrected
    Tin Can

  4. #4

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    Re: mounting gelatine filters between glass

    Interesting article. Looks a bit terrifying to be honest.

    I hope you mean that glass is 0.063" It could work, there is some margin for slightly thicker filter assemblies. Maybe I should visit a frame maker and try to find new glass.
    Expert in non-working solutions.

  5. #5
    Eric Woodbury
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    Re: mounting gelatine filters between glass

    You can buy lens adhesive from Edmunds Optical. Why not just use gelatin or poly without glass? Lighting gels are so cheap. You can get dozens of 100mm square gels from a single piece. No worries of reflections, refraction, rings, or mucking with gluing stuff together.

    Tin Can, you probably meant to say 0.063" or 1/16".

  6. #6
    Tin Can's Avatar
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    Re: mounting gelatine filters between glass

    Corrected, thank you

    I read the old technique, which did tell how to move bubbles and how much pressure to load it while setting

    It will be hard to find better glass delivered
    Tin Can

  7. #7

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    Re: mounting gelatine filters between glass

    Quote Originally Posted by Eric Woodbury View Post
    You can buy lens adhesive from Edmunds Optical. Why not just use gelatin or poly without glass?
    Problem is that this is for a tricolor camera, they don't go before the lens, they are mounted just before the film holders. There is no way to mount the gel. I'd have to make holders that are about 2mm wide around and total thickness should be about 2-3mm which isn't enough to give them strength or rigidity. The size isn't something standard, I have even chamfered corners. I have a set of Lee poly ones but I cannot find a way to mount them, certainly no way to keep them flat. On option would be to glue them to a single plate of glass. With the Devin that might be an option if I use the poly. But for the National Pḧotocolor the Lee filters aren't big enough so I need gelatins.

    Lighting gels are not suitable, I need wratten 25, 58 and 47.
    Expert in non-working solutions.

  8. #8

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    Re: mounting gelatine filters between glass

    Quote Originally Posted by Havoc View Post
    Problem is that this is for a tricolor camera, they don't go before the lens, they are mounted just before the film holders. There is no way to mount the gel. I'd have to make holders that are about 2mm wide around and total thickness should be about 2-3mm which isn't enough to give them strength or rigidity. The size isn't something standard, I have even chamfered corners. I have a set of Lee poly ones but I cannot find a way to mount them, certainly no way to keep them flat. On option would be to glue them to a single plate of glass. With the Devin that might be an option if I use the poly. But for the National Pḧotocolor the Lee filters aren't big enough so I need gelatins.

    Lighting gels are not suitable, I need wratten 25, 58 and 47.
    Those glass plates shift the focus by ⅓ rd the thickness of the glass. So, if your glass replacement is a different thickness then the original ones you have another difficult problem.

  9. #9
    Drew Wiley
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    Re: mounting gelatine filters between glass

    Can't find actual glass filters or possibly resin filters? They might need to be custom cut to the size needed and are likely to be somewhat costly, but you'd get far better performance without the same headache. Check with sources like Edmund Scientific (not the amateur gadget site - they have a huge commercial division which includes custom services), Hoya technical division (again, not just a retail list of popular filters), etc. Others have been down that road refurbishing old tricolor cameras, you're not the first.

  10. #10

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    Re: mounting gelatine filters between glass

    Replacing them by resin had been my first idea. That's why I ended up with the Lee polyester ones, but those are thin sheets. Not the solid thick ones I had expected. I haven't been able to find any except some astronomical filters at astronomical prices. Budget is also a consideration. Also in Europe it is hard to find a commercial source willing to trade to a private person. Even before they listen they want vat data, quantities etc.

    Quote Originally Posted by Bob Salomon View Post
    Those glass plates shift the focus by ⅓ rd the thickness of the glass. So, if your glass replacement is a different thickness then the original ones you have another difficult problem.
    This also means that replacing them by resin changes that as well (but a different amount). So replacing them by the (repaired) originals might not be a bad idea after all.
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