Can a ground glass substitute for Anti-Newton-Ring Glass?

[Joseph Kashi]

I am having difficulty finding Anti-Newton-Ring (ANR) glass for a contact print frame..

Does anyone know where I could get ANR glass in that size?

Would an 11x14 ground glass be an adequate substitute?

Any other suggestions for avoiding Newton Rings on an 11x14 contact print frame?

Thankyou.

[koraks]

I am having difficulty finding Anti-Newton-Ring (ANR) glass for a contact print frame..

I've never seen the need for this; do you get newton rings on your contact prints? What kind of printing process(es)?

Ground glass or museum glass should work in this application. There will be some diffusion, but since this is limited to the thickness of the negative, I don't expect the effect to be significant. Sorry, I haven't tried it, but it sounds like a relatively cheap experiment. AN glass in this size will likely be prohibitively expensive.

However, I've always had good results with plain, uncoated and untreated window glass in my contact frames.

[domaz]

I've never seen the need for this; do you get newton rings on your contact prints? What kind of printing process(es)?

Ground glass or museum glass should work in this application. There will be some diffusion, but since this is limited to the thickness of the negative, I don't expect the effect to be significant. Sorry, I haven't tried it, but it sounds like a relatively cheap experiment. AN glass in this size will likely be prohibitively expensive.

However, I've always had good results with plain, uncoated and untreated window glass in my contact frames.

Same experience for me. I have seen Newton rings with scanning quite a bit though. Usually only with 8x10 size film and larger. It probably had more to do with my DIY mounting of the film in the scanner than anything though.

[John Layton]

As per another post...I'm also on the lookout for some AN glass - but am also wondering...might it be possible to grind this, like one would a ground glass but not as coarse?

[Joseph Kashi]

Thank you for the quick responses and ideas. I'll contact my local framer and see about museum glass. He was not able to get ANR glass in that 11x14 size.

[Sal Santamaura]

...I'll contact my local framer and see about museum glass. He was not able to get ANR glass in that 11x14 size.

Not "museum glass." Rather, you need "non-glare" framing glass, which is lightly textured on one side, and should be placed in your contact printing frame with texture facing the film. I've done this very successfully. Ironically, non-glare glass is terrible for use in picture frames, but performs admirably as a substitute for ANR glass.

For the skeptics above, yes Newton's rings can be very troublesome when making contact prints, unless one is printing 320TXP negatives, which have a dull retouching layer added to the base side.

[Michael R]

Thank you for the quick responses and ideas. I'll contact my local framer and see about museum glass. He was not able to get ANR glass in that 11x14 size.

Just to be clear, you're talking about Newton rings forming between the base side of the film and the glass, right? (as opposed to between the film emulsion and the paper emulsion).

Framers won't typically have access to ground/etched ANR glass per se but will have access to various types of AR (anti-reflection/non-glare) glass. The non-glare type is most likely what you'll want. Stick with glass, not acrylic.

Assuming this is between the base side of the negative and the glass, there are other things that can work. Sal mentioned TXP 320 - a fixed out sheet of this can work well for smaller sizes. Yupo is another option.

[Joseph Kashi]

Just to be clear, you're talking about Newton rings forming between the base side of the film and the glass, right? (as opposed to between the film emulsion and the paper emulsion).

Framers won't typically have access to ground/etched ANR glass per se but will have access to various types of AR (anti-reflection/non-glare) glass. The non-glare type is most likely what you'll want. Stick with glass, not acrylic.

Assuming this is between the base side of the negative and the glass, there are other things that can work. Sal mentioned TXP 320 - a fixed out sheet of this can work well for smaller sizes. Yupo is another option.

That's correct - I am concerned about Newton Rings forming between the smooth back of the 11x14 sheet film and regular glass in a contact frame. I cannot find 11x14 Tri-X film listed anywhere, so that possibility seems out. I'll discuss the anti-glare products that the local framer might have available. That seems like the most workable, and least expensive, option. Thanks to all for the suggestions.

[Maris Rusis]

I've tried fine textured anti-glare framing glass in a 11x14 contact printing frame.
If I illuminate the contact frame with a large diffuse light source the texture of the anti-glare glass doesn't show in the contact print.
But if I use an enlarger directly as a light source the texture does show in the print. I think the combination of an enlarger head raised high to get the coverage but with the lens well stopped down to get a longer exposure time approximates a point light source.
And a point light source is merciless in revealing the slightest flaw or texture in the imaging system.

[Tin Can]

That's why I don't use a lens, and my DIY center filter does work with large aperture and paper filters

Only tested to 16X20" with vacuum glass NuArc

[Paul Ron]

Google is your friend....

a quick search found dozens of places to buy it.

https://www.knightoptical.com/stock/default/windows-and-diffusers/diffusers/anti-newton.html#:~:text=Anti-Newton%20glass%20sheets%20are%20lightly%20etched%20on%20one,etc%20without%20seeing%20the%20interference%20rings%20%28Newton%60s%20rings%29.

its expensive.

my scanner gives me rings if i lay the plain glass on top of the neg so i put some electric tape along the edges to lift the glass off the neg. its working fine.

[Drew Wiley]

Short answer - NO in an enlarger, possibly YES in a contact frame. But with ordinary etched picture glass you have two problems : 1) the etching pattern might in fact show, an 2) it's awfully darn thin and fragile. I always use real AN glass for both applications. Angle of incidence of the light source is also a factor, and it's important to test in each given combination.

Another trick you can try is a sheet of 5-mil frosted mylar or Duralar between the regular contact glass and the negative. That not only solves the Newton ring issue, but gives a slightly different handling of film grain (better defined) which I personally like. Check for any flaws over a light box first.

[Joseph Kashi]

Google is your friend....

a quick search found dozens of places to buy it.

https://www.knightoptical.com/stock/default/windows-and-diffusers/diffusers/anti-newton.html#:~:text=Anti-Newton%20glass%20sheets%20are%20lightly%20etched%20on%20one,etc%20without%20seeing%20the%20interference%20rings%20%28Newton%60s%20rings%29.

its expensive.

my scanner gives me rings if i lay the plain glass on top of the neg so i put some electric tape along the edges to lift the glass off the neg. its working fine.

The UK business that you reference is the only one that I've seen that might have the correct 11x14 size. All of the others that Google turned up in my several searches for ANR glass did not have correctly sized product. Thank you for the reference. I checked Edmund Scientific ( now Edmund Optics ) and they did not have ANR glass in large size that I requested.

[Tin Can]

Ask Howard Glass

https://flatglassproducts.howardglass.com/category/flat-glass-products-fabrication

[Drew Wiley]

Any outfit with serious a inventory of AN glass can cut and edge it to any reasonable size you need. If they can't, they're just a secondary distributor. Unfortunately, Scan Tech here on the Coast didn't seem to survive the pandemic shutdown. Who knows what happened to their glass inventory. They specially cut and shipped my order slightly prior to that. Before them, there was Focal Point. It's a niche business; but none of those outfits actually made their glass; it was all volume ordered from somewhere else. Big manufacturers don't like being pestered by tiny end-users, and certainly rarely sell to them unless one has special connections. But back when there were still multiple makers of AN glass, I got free samples from every one of them, for sake of comparison. I just knew how to sound like a research project, and was not in fact fibbing about it.

[Hugo Zhang]

Chamonix has made some 11x14 and 16x20 contact printing frames with Anti-Newton-Ring glass. I am a happy user. Newton-rings bothered me for years since I contact print only. I have yet to put these frames in our online shop yet as I thought they were too expensive with FedEx shipping included. I have changed my mind after a few months of use.

[Sal Santamaura]

Chamonix has made some 11x14 and 16x20 contact printing frames with Anti-Newton-Ring glass. I am a happy user. Newton-rings bothered me for years since I contact print only. I have yet to put these frames in our online shop yet as I thought they were too expensive with FedEx shipping included. I have changed my mind after a few months of use.

I look forward to seeing them on your Web site. Also, please ask Hass to consider making one 10x12, an ideal size for 8x10 negatives.

[Hugo Zhang]

I look forward to seeing them on your Web site. Also, please ask Hass to consider making one 10x12, an ideal size for 8x10 negatives.

I had one 10x12 custom made for myself a few months ago. 11x14 and 16x20 ones have one inch space on each side as well.

[Sal Santamaura]

I had one 10x12 custom made for myself a few months ago. 11x14 and 16x20 ones have one inch space on each side as well.

Does that mean one labeled "8x10" would really be 10x12? :)

[Hugo Zhang]

Yes, 8x10 printer has a space for 10x12.

[Hugo Zhang]

Yes, 8x10 printer has a space for 10x12.

My poor memory. My 8x10 contact printing frame has an ANR glass with a measurement of 223mm x 274mm.

[Sal Santamaura]

My poor memory. My 8x10 contact printing frame has an ANR glass with a measurement of 223mm x 274mm.

Which is about 8-3/4 by 10-3/4 inches. Depending upon how wide the frame rabbet upon which that glass rests is, it could be perfect. As long as the frame doesn't mask an 8x10 negative, which is slightly less than 8x10 inches, you might have something even better than 10x12, especially if the frame's rear opening is just large enough to accept 8x10 paper while centering it on the glass. Such a configuration would eliminate all the fussing to align negative and paper.

[Hugo Zhang]

Which is about 8-3/4 by 10-3/4 inches. Depending upon how wide the frame rabbet upon which that glass rests is, it could be perfect. As long as the frame doesn't mask an 8x10 negative, which is slightly less than 8x10 inches, you might have something even better than 10x12, especially if the frame's rear opening is just large enough to accept 8x10 paper while centering it on the glass. Such a configuration would eliminate all the fussing to align negative and paper.234655

The glass is actually a little bigger with usable area about 8 3/4 x 10 3/4 inches.

[Drew Wiley]

I have zero alignment issues with 8x10 film because I use the same pin registered contact frame for contact printing as for masking purposes. Its overall AN plate glass size is about 10X12. Laying around in storage I have a full 16x20-ish contact frame which I inherited but never even used; but I do recollect putting a sheet of AN glass in it too, though might have later cannibalized that same sheet for a different application. Regardless, I'd need a cordless indoor bulldozer to find it that antique mahogany contact printing frame.

[RichardRitter]

Over the years of printing in the same darkroom I have found that I would have problems with Newton rings and then go for months with out any problems. Winter time was the problem time. the dark room would be below 40 % humidity and sometimes as low as 15%.

[Tin Can]

Does the pressure PSI used make a difference?

I have 3 high pressure contact printers with no problems

[Michael R]

To make a long story short, the formation of the Newton ring interference pattern requires two things: (1) imperfect contact ie places where there are extremely thin air gaps and other places where there is direct contact, (2) non-scattering reflection between the two surfaces.

Regarding an example of item (1), suppose you have an area of extremely thin non-contact with a contact spot in the middle. The Newton ring pattern will radiate outward from the contact point. The rings have to do with the relationship between the thickness of the air space and wavelengths of light. As the air space increases from zero moving outward from the point of contact, the rings are the alternating interference from the light reflecting between the surfaces.

So, it is not the amount of pressure per se. Contact is contact. To the extent more or less pressure either improves or worsens item (1) above, it can either help or cause problems. It depends.


Does the pressure PSI used make a difference?

I have 3 high pressure contact printers with no problems

[Oren Grad]

So, it is not the amount of pressure per se. Contact is contact. To the extent more or less pressure either improves or worsens item (1) above, it can either help or cause problems. It depends.

The issue is distribution of pressure, and the problem is that the devices most often used to impose pressure - typically, springs arranged in various ways on the removable back of a printing frame, with the back often covered with a layer of felt - don't provide it anywhere near evenly. No, the wooden back and the felt don't spread the pressure around all that well.

I've always had issues with Newton's rings in my darkroom with any spring-backed frame I've ever used. I've had best luck skipping the frame, just building a stack with a thin piece of glass sitting on the enlarger baseboard, then paper, negative, and finally a thick piece of glass, substantially larger than the paper, on top. Yes, the top glass, negative and paper need to be handled with every exposure. C'est la vie, haven't yet found any other way that works enough of the time.

Long ago I did some experiments with coated AR glass, with inconsistent results. I eventually gave up because I was driving the local pro framing shop crazy searching for large enough pieces without coating flaws that would be visible in the prints. Maybe the production process and handling methods for AR glass have improved since then.

Tried various textured glasses too, but the texture always showed up in the prints.

Finally, a big YMMV. None of the above is to say that my approach is the correct one and if only you do the same, you will have no problems. This is so exquisitely dependent on local conditions that there's no alternative to just trying different approaches until you find something that works for you.

[Tin Can]

I wish we had some Fuji Prescale Pressure sensitive film

https://www.sensorprod.com/campaign/sensor-film-reveals-surface-contact-pressure-distribution-and-magnitude/?utm_term=fujifilm%20pressure%20paper&utm_campaign=prescale&utm_source=google&utm_medium=ppc&mcode=prescale&gclid=Cj0KCQiAiJSeBhCCARIsAHnAzT-JZZvGq4eERCgP8eQq8wUYC-LU2ZxPCfHUXNj2JIvYvcgJvE_jNSgaAq66EALw_wcB

We could quantify what works

I used it for decades

I use a NuArc vacuum press with what must be tempered glass. The rubber bottom has many many vacuum suction holes

It bends the glass, I also add a large matt board under the neg, then top with printing paper and neg neg

For 8X10 and smaller I use a 1940's printer with lamp under the stack. It has a big hard pillow that forces the neg and print together. Works fast for multiples.

I am still working with a 20X36" 3/8" tempered glass for gravity printing long negs

I am inspired by the very long contact prints made with Circut film cameras

https://en.wikipedia.org/wiki/Cirkut_(camera)

[Drew Wiley]

This foggy coastal climate is Newton Ring Hell. It sure doesn't help that some modern films are just so darn slick - Acros and Delta 100 being among the worst, and TMax often problematic too. I lust for the good old days of retouching "tooth" surfaces on sheet films. Kodak's current color sheet films have a scanning-improvement overcoat which helps. But roll films, yikes! Aerosol AN spray cans have gone the way of dinosaurs, probably due to enviro nasties in the propellant.

This time of year I have to up the utility bill a little and pre-heat the enlarging room well in advance, to prevent any condensation; and I pre-heat the cold light too, if that particular enlarger is the one being used.

Right now, despite the stunning amount of rainfall we've had in the last two weeks, rings have not been much of a logistical problem, giving how I routinely use AN glass. But ironically, once things start warming up later in Springtime, all that moisture in the soil starts turning into humidity and abruptly ends certain kinds of darkroom tasks, especially seasonal masking or film duping work, which really tempts Newton Ring formation somewhere in the cumulative exposure sandwich.

The micro-dimple pattern of certain Otho Litho films like current Arista not only helps efficient drawdown under a vac blanket, but is an excellent way to defeat N. Rings as well. Too bad it's so miserable for general shooting.

[Sal Santamaura]

...I lust for the good old days of retouching "tooth" surfaces on sheet films...

No need to lust. Just learn to love 320TXP. It still has that dull retouching layer on its base side. Never a ring when in contact with plain glass.

[Hugo Zhang]

Just put some pictures of our contact print frame online.

https://www.chamonixviewcamera.com/accessories/silversolutionbox

[Tin Can]

Good, I have 100 sheets 11X14 320TXP

I will use carefully


No need to lust. Just learn to love 320TXP. It still has that dull retouching layer on its base side. Never a ring when in contact with plain glass.

[Sal Santamaura]

Just put some pictures of our contact print frame online.

https://www.chamonixviewcamera.com/accessories/silversolutionbox

Looks beautiful! I have two questions:


Is that felt or foam on the hinged back?
When will it be possible to order an 8x10 version?

[Hugo Zhang]

Looks beautiful! I have two questions:


Is that felt or foam on the hinged back?
When will it be possible to order an 8x10 version?



A layer of rubber foam on the back.
I don't know when we will make 8x10 version. It will depend on the demand as we usually make them in batches. I had to wait for five months for my custom made 8x10 frame.

[Tin Can]

Here is my 'garbage' as some here called it when I got it

My 11X14 Levi Copy camera came with 2 very heavy duty holders

I converted one for Alt Printing, obviously it can copy normal paper

Cut out the center wood, instilled 1/4" tempered plate glass with room for 1/4" rebate

The 3/8" felt is perfect

I like the Darkslide, as it is handy when traveling

Very heavy duty with nice wood

https://live.staticflickr.com/65535/52633068296_e8d1459c6f.jpg (https://www.flickr.com/gp/tincancollege/vgXZJh017F)IMG-1560 (https://www.flickr.com/gp/tincancollege/vgXZJh017F) by TIN CAN COLLEGE (https://www.flickr.com/photos/tincancollege/), on Flickr

https://live.staticflickr.com/65535/52633555943_7b4cb2bdd6.jpg (https://www.flickr.com/gp/tincancollege/D15rYU2X02)IMG-1561 (https://www.flickr.com/gp/tincancollege/D15rYU2X02) by TIN CAN COLLEGE (https://www.flickr.com/photos/tincancollege/), on Flickr

https://live.staticflickr.com/65535/52633322989_9c9ede4be9.jpg (https://www.flickr.com/gp/tincancollege/JT2Z7cQu1j)IMG-1562 (https://www.flickr.com/gp/tincancollege/JT2Z7cQu1j) by TIN CAN COLLEGE (https://www.flickr.com/photos/tincancollege/), on Flickr

https://live.staticflickr.com/65535/52633068501_5e05fec594.jpg (https://www.flickr.com/gp/tincancollege/Dd1381SuBP)IMG-1563 (https://www.flickr.com/gp/tincancollege/Dd1381SuBP) by TIN CAN COLLEGE (https://www.flickr.com/photos/tincancollege/), on Flickr

[Erik Larsen]

Looks like a fabulous and innovative printing frame Hugo, well done!