Can it be a solution for avoiding newton rings

[Laci Toth]

What if I just tape a thicker parcel/multi purpose tape on the glass (or two layers) like a frame so there’s a tiny gap between the negative and the glass when contact printing so it might help avoiding newton rings?

[Vaughn]

-edited to remove mistaken visualization-

One starts to lose sharpness quickly without firm contact.

Sometimes excessive pressure causes the rings, as does any hint of moisture. Its a physics thing, dang it...some sort of light interference happening between two tightly held-together smooth transparent surfaces.

There is anti-newton glass (a little rough on one side), and I believe there are some sprays one can use on glass to get it to act like anti-newton glass.

Just a wild thought -- have not tried it: There is clear shelf-lining paper with an adhesive backing. I wonder if one covers a sheet of glass with it, the plastic surface might not create newton rings as much (or at all) like the glass surface does.

[Eric Woodbury]

Make the top of the sandwich a diffuse material and the rings go away. Materials such as Satinice and white plexilgass. Also, as Vaughn noted, use any textured material above that touches the top of the negative. And nowadays, altho I have not tried, the coated museum glasses would probably work with coating towards the negative.

[Alan9940]

And nowadays, altho I have not tried, the coated museum glasses would probably work with coating towards the negative.

I would definitely try this idea! Many years ago, Ron Wisner and I tackled this issue because I was having terrible ring issues at the time. He wound up sending me a single-coated sheet of heavy glass (the same coating used on lens elements, I believe) and, voila, rings gone!

[Jim Noel]

Museum glass works beautifully, but is expensive. I also have some "non-glare" glass for framing which I like.

[Laci Toth]

Make the top of the sandwich a diffuse material and the rings go away. Materials such as Satinice and white plexilgass. Also, as Vaughn noted, use any textured material above that touches the top of the negative. And nowadays, altho I have not tried, the coated museum glasses would probably work with coating towards the negative.
I found it both satinised glass and plexiglass as well. The latter is dirt cheap. What you reckon how thick it should be? Is the glass’ weight is enough or should I tape it on the baseboard or easel?

[ic-racer]

I used to lift up an edge of the glass and set it down just before the exposure. The Newton rings would move around before settling, and this movement eliminate them from visibility in the print. Worked most of the time when making proof prints.

[Laci Toth]

-edited to remove mistaken visualization-

One starts to lose sharpness quickly without firm contact.

Sometimes excessive pressure causes the rings, as does any hint of moisture. Its a physics thing, dang it...some sort of light interference happening between two tightly held-together smooth transparent surfaces.

There is anti-newton glass (a little rough on one side), and I believe there are some sprays one can use on glass to get it to act like anti-newton glass.

Just a wild thought -- have not tried it: There is clear shelf-lining paper with an adhesive backing. I wonder if one covers a sheet of glass with it, the plastic surface might not create newton rings as much (or at all) like the glass surface does.
Thanks for the idea! I’ve seen these adhesive materials with frost effect. I’m just wondering if the plexiglass or acid etched glass or these adhesive stuffs surface will be visible on the prints?

[Vaughn]

Stick a strip of sticky tape on a piece of glass and give it a test! Perhaps no negative and exposed to light gray...look for any pattern formed under the tape...or do the test with an image.

or

Lay your negative on the photo paper, cover half with your regular glass and the other half with plex and determine if there is any quality difference. Use an image with large areas of even tonality.

[Bob Salomon]

Thanks for the idea! I’ve seen these adhesive materials with frost effect. I’m just wondering if the plexiglass or acid etched glass or these adhesive stuffs surface will be visible on the prints?

Not if it is AN glass and is on the base side of the film as you focus on the emulsion side.

[Laci Toth]

I used to lift up an edge of the glass and set it down just before the exposure. The Newton rings would move around before settling, and this movement eliminate them from visibility in the print. Worked most of the time when making proof prints.
Interesting idea! My question might be funny but how much time do the rings need to settle? As I want to do lith prints and use an enlarger without lens, the exposure time can be long.

[Hugo Zhang]

All my printings are contact printing and all my contact printing frames give me Newton rings. Should I replace them with Tru Vue Museum glass? They are made for picture frames, not contact printers.


Any links for the glass you use for contact printing that does not give you Newton ring?

[Hugo Zhang]

I have also noticed that 810 Tmax film gives the most Newton ring as its very shiny side is pressed against the glass.

[Laci Toth]

Stick a strip of sticky tape on a piece of glass and give it a test! Perhaps no negative and exposed to light gray...look for any pattern formed under the tape...or do the test with an image.

or

Lay your negative on the photo paper, cover half with your regular glass and the other half with plex and determine if there is any quality difference. Use an image with large areas of even tonality.
Alright, I’ll give them a try! Thanks!

[Ron McElroy]

I just looked at the specs of museum glass from this company https://tru-vue.com/ and all of their products seem to have UV blocking coatings. I understand the desire to use it for framing, but in a contact frame it would be a problem for any alt processing.

[Laci Toth]

All my printings are contact printing and all my contact printing frames give me Newton rings. Should I replace them with Tru Vue Museum glass? They are made for picture frames, not contact printers.


Any links for the glass you use for contact printing that does not give you Newton ring?
I’ve just found them, though I give the ideas of this thread a go.
http://www.betterscanning.com/scanning/mainintro.html

[Hugo Zhang]

Laci,

My 810 contact printer are using 9x11 and 9 5/8 x 11 11/16 glasses and the betterscanning offers 8x10 glass.


Has anyone used contact printing Mylar sheets? How does that work?

[Hugo Zhang]

Found this one:

http://fpointinc.com/glass.htm

But its online ordering is not working and don't know if it is still in business.

[Drew Wiley]

You'll make it worse by that tape method. The film won't be flat, and where it does make contact with the glass, that's where you'll have rings. Anti-Newton glass is NOT frosted glass or non-glare picture glass. The real deal has a much more subtle effect. I routinely use it on BOTH sides of the film. I know that Bob might scream and stamp his feet about that, but not only is it necessary in this foggy climate, but works extremely well IF you have the right kind of glass. Mere coated glass has never done the trick for me. As a last resort you could use anti-Newton spray available from the same outfits that sell scanning fluids. But there's a distinct technique to using such sprays; and a fume hood is necessary for health reasons. Focal Point is no longer in business.

[Bob Salomon]

You'll make it worse by that tape method. The film won't be flat, and where it does make contact with the glass, that's where you'll have rings. Anti-Newton glass is NOT frosted glass or non-glare picture glass. The real deal has a much more subtle effect. I routinely use it on BOTH sides of the film. I know that Bob might scream and stamp his feet about that, but not only is it necessary in this foggy climate, but works extremely well IF you have the right kind of glass. Mere coated glass has never done the trick for me. As a last resort you could use anti-Newton spray available from the same outfits that sell scanning fluids. But there's a distinct technique to using such sprays; and a fume hood is necessary for health reasons. Focal Point is no longer in business.

Won’t stamp my feet.

[Hugo Zhang]

Drew,

What is your experience of putting a sheet of Mylar between the glass the negative?

Thanks.

[Bob Salomon]

Drew,

What is your experience of putting a sheet of Mylar between the glass the negative?

Thanks.

Newton rings are formed when one smooth surface, like the base side of film, comes in contact with another smooth surface.

Get AN glass and save time and money with things that can deteriorate image quality and not work.

[Bob Salomon]

Drew,

What is your experience of putting a sheet of Mylar between the glass the negative?

Thanks.

Newton rings are formed when one smooth surface, like the base side of film, comes in contact with another smooth surface.

Get AN glass and save time and money with things that can deteriorate image quality and not work.

[Ron_in_Alaska]

I have used a ground glass for contact printing color Cirkut negatives for years some are over 7 feet long. NO Newtons rings period. I ground the glass myself with carborundum. This doesn't affect the sharpness of the image either. Grinding glass is simple and fairly fast. The grit is from a lapidary supply and is very cheap.

[Eric Woodbury]

Bob, it takes both the closely spaced surfaces AND some degree of coherent light. This is why even a polished diffuse surface in contact with negative will NOT produce Newton's rings.

[Bernard_L]

Bob, it takes both the closely spaced surfaces AND some degree of coherent light. This is why even a polished diffuse surface in contact with negative will NOT produce Newton's rings.
The degree of coherence (i.e. small effective wavelength range) required to display interferences is directly related to the difference in path length between the interfering paths. The longer the path length, the smaller the wavelength range needs to be in order to display interference fringes. In the case of Newton rings, the surfaces are at or near contact, i.e. in physics jargon, near the white fringe (not coincidentally named so because interference fringes are visible even in "white" light when the path difference is close to zero).

Displaying interference fringes requires close contact OR (not AND) highly coherent light. With a laser, even my little sister can show fringes all over the room.

The reason(s) a diffuse surface, even in contact with a negative will not show Newton rings, are that:
(a) most of the surface is a few microns away from the negative; negligibly small in terms of negative flatness, but already "far" in the context of a wavelength range spanning 100 or 200 nanometers (low coherence)
(b) at/near those spots where the glass is actually touching the negative (doing its job of keeping it in a plane) the spacing varies from zero to one or more micrometers over a lateral distance of a few microns; over that distance, the Newton rings are present, but so closely spaced as being effectively invisible.

[Drew Wiley]

Hi Hugo. Mylar can certainly work, depending, but only on the upper side of a negative carrier or backside of the original neg between it and a contract frame glass. I use 5-mil mylar and sometimes 3-mil mylar FROSTED BOTH SIDES for masking and other contact printing scenarios. You buy a big sheet or two of it and put it over a lightbox to spot any blemishes, then cut down into the smaller sizes you need. You'll discover there's a slight linear grain a particular direction, and should orient the mylar the specific direction that will least affect something like open featureless skies. And it is important to use true mylar. It comes is different brand names, but should be distinguished from frosted or textured acetate, which has a much more perceptible pattern in any samples I've tested, and is not dimensionally stable like mylar. Clear textured mylar would be a trickier proposition, but one could hypothetically fix out a sheet of Arista Ortho Litho film stock, which is textured, and try that. The problem is more complex than certain foregoing posts would make it seem. I once had samples of 13 different kinds of AN surfaces in stock for testing. It can depend on the angle of incidence of the light, the degree of magnification relative to format size, ambient humidity, and especially on a high amount of contrast increase like using the highest grade on VC paper. I don't believe there's such a thing as a silver bullet that works best in every situation. Personal testing is mandatory.

[Peter De Smidt]

P99 acylic works well if heat isn't involved.

[Drew Wiley]

Nonglare acrylic sheet isn't stable. It bows toward the light side. It also is affected by long-term humidity changes. The biggest problem is that acrylic is so damn electrostatic, a dust magnet. There are antistatic cleaners that reduce that somewhat. I have a LOT of experience with this material. But it might indeed be a realistic answer under a cold light if the overall size is modest. I should probably try it in my own 8x10 cold light system, but currently have something relatively exotic for that.

[Barry Kirsten]

A few days ago I was thinking about Newton rings and wondering why I never get them. I think the answer is that I've been using the same sheet of 6mm thick glass for decades and in that time it's developed a coating of grease from handling which gets reinforced each time I wipe it before use. Just a thought.

[Peter De Smidt]

And I have a lot of experience making 6000 spi scans using it. BTW, anti Newton acrylic is used by Screen for both the scanning bed, and for hold-down sheets.

[Oren Grad]

Found this one:

http://fpointinc.com/glass.htm

But its online ordering is not working and don't know if it is still in business.

No, Mike closed the business last year.

[Drew Wiley]

I doubt I'd want acrylic underneath a neg. It's not even the correct kind of acrylic. Scratches easily, hydrates and dimensionally unstable, electrostatic. But it's easy to size, relatively cheap, and doesn't shatter. There is also an advantage to something a bit heavier if gravity is the primary factor in a carrier rather than compression clips. Acrylic would be a non-starter for any kind of registration work. But it's certainly worth experimenting with.

[Old_Dick]

Folks,

Here is a URL from APUG now photrio. They had similar questions.

http://www.apug.org/forum/index.php?threads/anti-newton-glass-and-huge-enlargements.135849/

[Peter De Smidt]

No, Mike closed the business last year.

He likely sourced the glass from somewhere. He might have cut it, but I doubt he made the texture.

[Drew Wiley]

His glass worked fairly well for LF enlargements and flatbed scanners. A bit too coarse for MF combined with very high MTF Apo enlrgr lenses. There are just too many potential variables to give a legitimate generic answer.