glueing polyester filters to glass for a tri-color camera

[Havoc]

Got a tri-color camera but the color filters are not usable anymore. They look like this:



They are a gelatine (I suppose) filter glued between 2 think glass plates.

So I bought new polyester color separation filters from LEE expecting them to be thick polyester like the usual 100x100mm slide in filters. But no, they are like gelatine filters, 0.15mm thick. That means I have to attach them to glass in order to use them.

What would be the best way to fix them to a thin glass plate? Without bubbles, not attacking the polyester, completely transparent. I suppose just clamping between 2 glass plates would not work, giving Newton rings. Glue might work but I have no idea what to use and certainly no idea how to do that without bubbles.

The camera itself:



Yep, still a lot of work on it.

[Larry Gebhardt]

Got a tri-color camera but the color filters are not usable anymore. They look like this:



They are a gelatine (I suppose) filter glued between 2 think glass plates.

So I bought new polyester color separation filters from LEE expecting them to be thick polyester like the usual 100x100mm slide in filters. But no, they are like gelatine filters, 0.15mm thick. That means I have to attach them to glass in order to use them.

What would be the best way to fix them to a thin glass plate? Without bubbles, not attacking the polyester, completely transparent. I suppose just clamping between 2 glass plates would not work, giving Newton rings. Glue might work but I have no idea what to use and certainly no idea how to do that without bubbles.

The camera itself:



Yep, still a lot of work on it.

You could put mineral oil on the filter between the glass plates and seal the edges. That would eliminate the Newton’s rings. Might be hard to seal it up without bubbles. I would try the Kami tape used from mounting on drum scanners.

[brucetaylor]

I don’t know what size your filters are, but Lee makes a holder for their 4x4 gelatin filters. I think it would be easier to use your filters “naked” rather than sandwiching between glass.

[Havoc]

You could put mineral oil on the filter between the glass plates and seal the edges. That would eliminate the Newton’s rings. Might be hard to seal it up without bubbles. I would try the Kami tape used from mounting on drum scanners.

Don't know about putting oil between 2 sheets. I'm a bit afraid it might creep everywhere and I don't see a way of sealing the edge so it won't occur.

I don’t know what size your filters are, but Lee makes a holder for their 4x4 gelatin filters. I think it would be easier to use your filters “naked” rather than sandwiching between glass.

They are about 100x80mm so using that frame wouldn't work. A frame might work, the originals do have a 2-3mm border. So such a fitting frame might be a solution but I don't see how to make one that is stiff enough with such a thin border to work with. You are right that using the filters naked would eliminate the problem of bubbles and Newton rings.

[cowanw]

I just had occasion to try to repair an ambrotype with a painted on glass black mat. the glass was broken so I decided to use this

https://www.google.com/shopping/prod...B,gclsrc:aw.ds

It was a bit viscous and I clamped a second piece of glass on to the front to fix the broken pieces in position. The glue doesn't fix until you shine the UV light on it.
I would consider trying this. Dilute the glue with a touch pf acetone to make it flow easier and cover the glass. Lay the filter on and cover that with saran wrap or waxed paper and clamp a second pane of glass over that to squeeze the air bubbles out, clean up with acetone, and then UV the areas you can , take the clamps off and UV the rest. hopefully the back glass and the paper or saran will come off. and a razor blade will get any residual off the front.
Try with non original glass first perhaps to test.
The glue is yellow but goes clear on curing.
You could use lens UV glue as well, but since but since Roger at Camtech passed I don't know where to get it..

[aaronnate]

How does that camera work?

When I worked in a special collections darkroom I floated the emulsion off nitrate negs and mated them with fixed out copy film bases to make prints and copy negs of. It was all done under water so there was no way for air bubbles to get between. Maybe that method would work.

[Havoc]

The UV link doesn't work, but I get the idea. Used some sort of glue like that for attaching a rear-view mirror to the windscreen. Might be an idea. I'm not going to reuse the original glass, I'm leaving the filters as they are and I'm going to make new ones. Maybe I should get a couple of glass panes extra and practice with some other filters.

How does that camera work?

When I worked in a special collections darkroom I floated the emulsion off nitrate negs and mated them with fixed out copy film bases to make prints and copy negs of. It was all done under water so there was no way for air bubbles to get between. Maybe that method would work.

There are 2 beam splitter pellicle films that make a part of the light fall on each filter. First should split 33/66, the next 50/50 so each filter gets 1/3-th of the light. They are still intact and seem to be working but so far I have no idea if they're still usable.

Your method is neat, it is a fool-proof way of doing this without bubbles. The more I think of it, the better it seems. It would need more glue but more chance of a good outcome. Going to think about it. Combined with the UV curing glue there is something to be said.

- get a recipient with enough glue to cover the glass
- get the filter under the glue surface without bubbles
- press to glass
- take out
- get surplus glue off the back
- cure
- trim borders

Might work.

[Larry Gebhardt]

Don't know about putting oil between 2 sheets. I'm a bit afraid it might creep everywhere and I don't see a way of sealing the edge so it won't occur.

That's what the Kami tape suggestion was for. Create the sandwich of glass, oil, gel, oil, glass and tape the edges. I've had some sealing mylar to a drum with mounting fluid behind it for weeks with no issues. I've also left some on glass for years and it removed cleanly. But I'm not taking those things out into the heat where it may behave differently.

[interneg]

The filters sound very like how Tiffen makes filters for the cinema industry - and I imagine there are other cinema optical companies who could bond suitable wratten # filters to optical glass flats.

[Drew Wiley]

Polyester is a obviously poly plastic, so it's going to be inherently resistant to glue. And polyester is also far less than ideal as a filter material in terms of optical clarity. I'd never use it for something like this.