Mounting gels between glass in a filter ring?

Doremus Scudder · Oct 30, 2011

I've got a couple of gels I use less than I should because of the inconvenience/risk of carrying them in the field. I'm thinking I could somehow mount a gel between glass in, say, a 67mm filter ring, thereby making it easier to carry and less prone to damage (not to mention more convenient to use).

Has anyone out there ever done this? If so, how, and how well did it work? I'm looking for "best practice" and experience here to help me cobble something together.

Thanks in advance,

Doremus Scudder
www.DoremusScudder.com

Jim Jones · Oct 30, 2011

You would be adding four air to glass surfaces, which may degrade the image.

Bob-D659 · Oct 30, 2011

That is how most pol filters are made, I'm not sure how you would get a good bond between the gel and the glass to exclude any air bubbles. UV cure optical cement maybe? I relaminated the edges of an old microscope pol filter with a soak in toluene and then clamping the filter in it's holder. So far so good.

Nicholas Lindan · Oct 30, 2011

Not just polarizers, but most 'glass' filters are gel filters glued between two glass rounds. B&W used to sell 'custom' filters were they would mount the gel of your choice - but that was 30 years ago... TTBOMK the gel is glued in with optical cement - used to be Canada Balsam but I am sure it is some UV curing something-or-other these days.

Jim Jones · Oct 30, 2011

If the gel isn't laquered, a drop of water centered on the top and bottom surfaces and then clamping it between two optical flats might let the gelatin adhere to the glass. If it is laquered, Bob's suggestion is probably better. Polarizing material is made of plastic, not gelatin, and may require a different technique than gelatin.

Ronald Moravec · Oct 30, 2011

I used to put a IR gel cut to a circle on the back side of a UV filter. Smallest bits of tape keep it in place. Store in a plastic filter box gel side down. I have had a few homemade one last for years this way.

I would NOT go with double filter sandwich.

Lee polyester filters are extremely durable. I had some that were in a flood and they are fine. Wratten gel get damaged if you look at them wrong.

M. Lointain · Oct 30, 2011

Ronald Moravec said:
I used to put a IR gel cut to a circle on the back side of a UV filter. Smallest bits of tape keep it in place. Store in a plastic filter box gel side down. I have had a few homemade one last for years this way.

I would NOT go with double filter sandwich............

Ditto. I have a nd gel done this way, lasting over a decade at this point.

Doremus Scudder · Oct 31, 2011

Many thanks to all for the replies, info and suggestions.

I don't think I'm really up to doing any optical cementing, plus, I imagine one would need to get their hands on some very thin rounds (just using two normal-thickness UV filters or the like would likely not fit into a ring. Too bad I know of no one who still offers this service.

I had toyed with the idea of screwing two filters together with the gel in the middle, realizing, of course, that the extra air-to-glass surfaces might cause a bit more flare (which could be attenuated somewhat by using two coated filters).

However, Ron, I think I'll go with your suggestion and see if I can just use a single filter to protect one side of the gel and store it carefully to protect the other side. Maybe I can find a filter with a retaining ring (I think I've got a few of those running around somewhere), remove the glass, insert the gel, then replace the glass and retaining ring.

Any other brilliant ideas?

TIA

Doremus

Early Riser · Oct 31, 2011

Just sticking a gel between two layers of glass will give you the possibility of newton rings, and as someone said more air surfaces. The use of a drop of water as a means to stick the gel to the glass is also problematic as it will melt the gelatin. While it's true that filter manufacturers produce some products by using a glass sandwich effect, they have the means to insure a complete and even sandwich without air bubbles or newtons and also maintain plano parallelism.

So just use the gels as they were intended, in a gel filter holder and when they get damaged toss em.

pgomena · Oct 31, 2011

Or just buy high-quality coated glass filters. At the price of gels these days, they're worth the investment.

Peter Gomena

Doremus Scudder · Oct 31, 2011

Peter,

All the filters I normally use are coated glass filters, either B+W or Heliopan. However, I'd like to use my Wratten 44a a bit more than I do now.
Know of any sources for a 44a in glass?

Best,

Doremus

AgX · Oct 31, 2011

Doremus, these standard Heliopan and B&W ones are, to my information, not from coated glass but from homogenously coloured glass.

Doremus Scudder · Nov 1, 2011

AgX,

What I meant was that the B+W and Heliopan filters are anti-reflective coated, like lenses. I do believe you are right that the color of the filter in the glass of the filter itself.

Best,

Doremus

Mounting gels between glass in a filter ring?

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