Stretched paper? - Ilford 16x20 Multigrade FB not dimensionally stable?

Ardpatrick · Feb 3, 2025

I'm printing on 16x20 Ilford multigrade FB glossy, for exhibition purposes. My prints have a border, and a visible rebate (Avedon style) and the intention is they will fit into an off-the-shelf frame I have access to. So dimensional stability is important.

After reading the thread here on drying and flatness I have been experimenting with the drying method of taping to glass and air drying for flatness. Results are good, except I noticed the image dimensions of a dry print had changed by more than 6mm (1/4 inch). Suspecting the taping method I rewet a 'spare' print thoroughly in water and hung it on a leaning glass sheet with a view to waiting for most of the excess water to drain before taping. I decided to measure the wet print just laying on the glass. It's 20 inches on the long side pretty exactly, but just under 16.5 inches on the short side! That is before taping it. This is uncut Ilford 16x20 paper, carefully handled with thongs (it's an exhibition print etc - I'm pretty experienced).

Anyone able to break this down for me?

Ardpatrick · Feb 3, 2025

Ardpatrick said:
I'm printing on 16x20 Ilford multigrade FB glossy, for exhibition purposes. My prints have a border, and a visible rebate (Avedon style) and the intention is they will fit into an off-the-shelf frame I have access to. So dimensional stability is important.

After reading the thread here on drying and flatness I have been experimenting with the drying method of taping to glass and air drying for flatness. Results are good, except I noticed the image dimensions of a dry print had changed by more than 6mm (1/4 inch). Suspecting the taping method I rewet a 'spare' print thoroughly in water and hung it on a leaning glass sheet with a view to waiting for most of the excess water to drain before taping. I decided to measure the wet print just laying on the glass. It's 20 inches on the long side pretty exactly, but just under 16.5 inches on the short side! That is before taping it. This is uncut Ilford 16x20 paper, carefully handled with thongs (it's an exhibition print etc - I'm pretty experienced).

Anyone able to break this down for me?

Btw

I just measured a print air dryed on a metal print viewing board (held with magnets) and it's just under 20 inches long, and exactly 16 inches high.

To be clear, I'm trying to understand how to get dry flat prints that match my intended final dimensions without having to trim them excessively. I have allowed for a slight trim, but not for a difference in aspect ratio from uneven drying.

Ardpatrick · Feb 3, 2025

retina_restoration said:
So, what are the dimensions of this paper before exposure and development??

It's Ilford 16 x 20 inch paper.

Ardpatrick · Feb 3, 2025

I have just measured an unprocessed sheet, under the saflight in the darkroom. It appears to measure exactly 16 x 20 inches.

Ardpatrick · Feb 3, 2025

Actually it's the complete opposite.

The shorter dimension is stretched significantly from its factory cut dimension. The longer dimension is relatively consistent.

pentaxuser · Feb 3, 2025

Ardpatrick said:
Actually it's the complete opposite.

The shorter dimension is stretched significantly from its factory cut dimension. The longer dimension is relatively consistent.

So drying has lengthened one side, that being the 20 inch part. Not what I understand paper going from wet to dry state does at all and have never heard this to be the case in any threads here that have as their subject drying FB paper

I'll be interested to see what others have to say by way of an explanation

pentaxuser

Ardpatrick · Feb 3, 2025

As I've explained, different methods produce different results. The method I would like to use (because it results in very flat prints) produces results where the shorter side is stretched, it seems. I'm hoping someone has something insightful to share with me on the matter.

retina_restoration · Feb 3, 2025

Ardpatrick said:
As I've explained, different methods produce different results. The method I would like to use (because it results in very flat prints) produces results where the shorter side is stretched, it seems. I'm hoping someone has something insightful to share with me on the matter.

Ask Ilford.

MattKing · Feb 3, 2025

I would use the Contact page on Harman Technology's Ilford Photo website.
@Harman Tech Service sometimes check in here as well - perhaps they will see this.
I'll tweak the thread title as well.

Lachlan Young · Feb 3, 2025

Ardpatrick said:
dimensional stability is important

Don't use FB paper then. These characteristics are inherent to FB paper subjected to wet/ dry cycles.

None of this is atypical or unusual.

Ardpatrick · Feb 3, 2025

pentaxuser said:
So drying has lengthened one side, that being the 20 inch part. Not what I understand paper going from wet to dry state does at all and have never heard this to be the case in any threads here that have as their subject drying FB paper

I'll be interested to see what others have to say by way of an explanation

pentaxuser

Lachlan Young said:
Don't use FB paper then. These characteristics are inherent to FB paper subjected to wet/ dry cycles.

None of this is atypical or unusual.

I agree. I never claimed it was atypical nor unusual. Nor am I claiming I have mis-sized paper, nor that the paper is a bad batch etc.

As you say, the paper has characteristics that are intrinsic. But given that, surely users would note something as significant as a change in the size of printed images as they dry. My enquiry is really about drying this paper. Different techniques seem to produce different dimensional results, affecting things like aspect ratio etc. Obviously it matters to me, but I imagine it's also quite significant for many users who invested a lot in their distortion free optics and their Apo-rodagon N's.

I have contacted Ilford already, and I await a response.

koraks · Feb 3, 2025

Ardpatrick said:
It's 20 inches on the long side pretty exactly, but just under 16.5 inches on the short side!

I can't explain that. Shrinkage, also along one dimension - yes, absolutely. Paper bases do that. But growing in size after rewetting and drying...no, never heard of that happening. Weird! I'm curious as to what the manufacturer may be able to tell about this.

Doremus Scudder · Feb 3, 2025

Don't put stretching stress on the paper. Obviously, when you're taping it to the glass, you're pulling to get the paper flat. You need to realize that the paper, when wet, is likely overall larger than when dry (that's why there's drydown).

Try marking your glass to the exact dimensions you'd like (plus maybe a tiny bit, and taping the prints to that, letting them shrink as they dry and then supply their own tension. Still, this might not get the prints entirely flat.

Really, the best way of getting fiber-base prints flat for display is dry mounting.

If I were you, I'd be leaving just a bit of room so I could trim the print border to exact dimensions, say, 15 3/4 x 19 3/4 or something like that and then dry mount those to the bottom mat board.

How are you planning on mounting the prints? Don't you have a larger board behind the print anyway (kind of standard for display, having a border outside the print)?

Best,

Doremus

dpurdy · Feb 3, 2025

Paper fibers swell when wet. The paper was originally made in rolls that are calenderd to smooth them out and then cut to sizes. When paper swells and shrinks from processing and washing it seems to me unlikely to exactly regain it's freshly made and pressed size. I have noticed forever that wetted paper gets larger and then shrinks down when dry. I always assumed that is how to account for the dry down affect. Like a ballon when you stretch it out it's printing, if there is some, gets lighter. Then you let the air out and it gets dark again.

Ardpatrick · Feb 3, 2025

Doremus Scudder said:
Don't put stretching stress on the paper. Obviously, when you're taping it to the glass, you're pulling to get the paper flat. You need to realize that the paper, when wet, is likely overall larger than when dry (that's why there's drydown).

Try marking your glass to the exact dimensions you'd like (plus maybe a tiny bit, and taping the prints to that, letting them shrink as they dry and then supply their own tension. Still, this might not get the prints entirely flat.

Really, the best way of getting fiber-base prints flat for display is dry mounting.

If I were you, I'd be leaving just a bit of room so I could trim the print border to exact dimensions, say, 15 3/4 x 19 3/4 or something like that and then dry mount those to the bottom mat board.

How are you planning on mounting the prints? Don't you have a larger board behind the print anyway (kind of standard for display, having a border outside the print)?

Best,

Doremus

Thanks for the solid advice, but to be clear, I'm not stretching the paper knowingly. I use Kaiser print thongs to handle the paper during processing, and I 'paste' the wet paper to glass without even the use of a squeegee. It naturally adheres to the glass when wet. I put the gum tape over-lapping the very edge of the sheet. There is no force involved.

I have just made a print now between responding to this thread. The wet print appears to be about 16.5 inches on the long side. Obviously there is stretching during processing. That makes me think that what is happening is that the tape on glass method prevents the paper from returning to a similar (never exactly 16 x 20) dimension as it does when air dried.

Pieter12 · Feb 3, 2025

Ardpatrick said:
It's Ilford 16 x 20 inch paper.

That is no guarantee it is exactly 16x20"

koraks · Feb 3, 2025

Doremus Scudder said:
(that's why there's drydown).

No, I don't think this is the main explanation for drydown. AFAIK drydown is caused by the fact that the gelatin emulsion swells considerably when wet, and thus, as it dries, it shrinks back again. This effect is vastly more dramatic than the more marginal dimensional shifts of the paper base. The swelling of the emulsion will increase the distance between the silver grains, making it possible for light to bounce around a bit in the gelatin layer even in photographically dense areas, reflecting some light back to the viewer. As the gelatin emulsion dries into its more compact, thin state, the light is sealed off from the white baryta base more effectively.

Ardpatrick said:
I'm not stretching the paper knowingly

No, you're not; I'm very familiar with the method you use as I do the same a lot of the time, with silver gelatin papers and also with carbon transfer prints. The wet prints are generally of virtually the same dimensions as the original (dry) paper base. But after drying, they tend to shrink, pulling the paper tape across the borders taut. With carbon transfer prints this happens so pronouncedly that even a small 8x10" print can shrink along one dimension by as much as half an inch.

It's still very puzzling that your paper somehow ends up larger after processing. I can't explain that, and I'd definitely double check if it's really happening.

DREW WILEY · Feb 3, 2025

No kind of paper is dimensionally stable. Drymounting can help; but typical mounting substrates like museum board are themselves hydroscopic and therefore dimensionally unstable, especially under circumstances of varying humidity. All this just come with the territory. Some mounting board brands are more stable than others. But I typical factor about 1/16th inch per side variance for a 22X26 4-ply mount for a 16X20 print. Plexiglas itself can expand and contract more than that. Every pro picture framer know that; otherwise, they won't be in business for long. But one has to be very careful how they measure and square sheet materials, and never blindly assume the factory has done it correctly.

In other words, I think you're on the wrong track to begin with, by assuming you can pre-dry a print to exactly fit an acrylic box frame.
It doesn't work that way. You want a bit of surplus image border which can be trimmed down to size afterwards. Or if it were me, I would have drymounted the trimmed image to at least 2-ply of mounting board first, and then trimmed that to slightly less than the internal dimensions of the frame.

And trying to dry a print with the emulsion in contact with a smooth surface sounds dicey to me. I won't try to technically explain what you seems to be describing as anomalous, not having seen any of the technique or its results in person. Ilford's paper base has recently changed, in just the past few years it seems, with a different fiber "weave".

Ardpatrick · Feb 3, 2025

DREW WILEY said:
No kind of paper is dimensionally stable. Drymounting can help; but typical mounting substrates like museum board are themselves hydroscopic and therefore dimensionally unstable, especially under circumstances of varying humidity. All this just come with the territory. Some mounting board brands are more stable than others. But I typical factor about 1/16th inch per side variance for a 22X26 4-ply mount for a 16X20 print. Plexiglas itself can expand and contract more than that. Every pro picture framer know that; otherwise, they won't be in business for long. But one has to be very careful how they measure and square sheet materials, and never blindly assume the factory has done it correctly.

In other words, I think you're on the wrong track to begin with, by assuming you can pre-dry a print to exactly fit an acrylic box frame.
It doesn't work that way. You want a bit of surplus image border which can be trimmed down to size afterwards. Or if it were me, I would have drymounted the trimmed image to at least 2-ply of mounting board first, and then trimmed that to slightly less than the internal dimensions of the frame.

And trying to dry a print with the emulsion in contact with a smooth surface sounds dicey to me. I won't try to technically explain what you seems to be describing as anomalous, not having seen any of the technique or its results in person. Ilford's paper base has recently changed, in just the past few years it seems, with a different fiber "weave".

Just on your last paragraph - to clarify: the emulsion side faces air. The base is in contact with the glass.

Re; Your previous points - Yes I have to reluctantly agree that I can now see that I haven't taken the right approach here. It would have been more sensible to complete the print production, as clearly, FB paper is quite dimensionally unstable. At this point I'm too far in to reverse, so I think my best choice is to air dry the prints, without glass, and allow that they will be wavy. Air drying seems to allow the print to dry much closer to its original specified dimension - certainly to within reasonable tolerances. Thanks for your thoughts on this.

Ardpatrick · Feb 3, 2025

koraks said:
No, I don't think this is the main explanation for drydown. AFAIK drydown is caused by the fact that the gelatin emulsion swells considerably when wet, and thus, as it dries, it shrinks back again. This effect is vastly more dramatic than the more marginal dimensional shifts of the paper base. The swelling of the emulsion will increase the distance between the silver grains, making it possible for light to bounce around a bit in the gelatin layer even in photographically dense areas, reflecting some light back to the viewer. As the gelatin emulsion dries into its more compact, thin state, the light is sealed off from the white baryta base more effectively.

No, you're not; I'm very familiar with the method you use as I do the same a lot of the time, with silver gelatin papers and also with carbon transfer prints. The wet prints are generally of virtually the same dimensions as the original (dry) paper base. But after drying, they tend to shrink, pulling the paper tape across the borders taut. With carbon transfer prints this happens so pronouncedly that even a small 8x10" print can shrink along one dimension by as much as half an inch.

It's still very puzzling that your paper somehow ends up larger after processing. I can't explain that, and I'd definitely double check if it's really happening.

I think what I'm finding is that the prints swell. and are larger when they are processed. With air drying they shrink sort of uniformly. With taping to glass they shrink on the long dimension, but not on the short dimension. So the paper ends up bigger than it started. I'd be interested to see if you have similar results.

Lachlan Young · Feb 3, 2025

koraks said:
I can't explain that. Shrinkage, also along one dimension - yes, absolutely. Paper bases do that. But growing in size after rewetting and drying...no, never heard of that happening. Weird! I'm curious as to what the manufacturer may be able to tell about this.

Paper in manufacturing/ coating is dried in very specific ways (impingement drying + controlled web tension), which no end user is going to be able to replicate. Too much tension can cause all sorts of problems - and as some are finding out, the final sheet will behave differently parallel to and perpendicular to the grain direction of fourdrinier paper when it is wet. Getting tied up in knots about trying to force a particular sheet size into a pre-made frame (many of which manage to be a size that neither fits 40x50cm nor 40.6x50.8cm/ 16x20" well) without testing seems a singularly pointless endeavour - especially when working with a bigger sheet and trimming down to an exact fit is not difficult - and cheaper than getting a customised frame made.

DREW WILEY · Feb 3, 2025

I don't fight the drying curl. I just let the prints fully air dry on fiberglass screens, emulsion-up. Then I place them under the weight of a big sheet of thick plate glass. That sufficiently flattens them for stacked storage purposes, until some are selected for permanent drymounting. Properly used, a drymount press is an excellent flattening agent.

Ardpatrick · Feb 3, 2025

Lachlan Young said:
Paper in manufacturing/ coating is dried in very specific ways (impingement drying + controlled web tension), which no end user is going to be able to replicate. Too much tension can cause all sorts of problems - and as some are finding out, the final sheet will behave differently parallel to and perpendicular to the grain direction of fourdrinier paper when it is wet. Getting tied up in knots about trying to force a particular sheet size into a pre-made frame (many of which manage to be a size that neither fits 40x50cm nor 40.6x50.8cm/ 16x20" well) without testing seems a singularly pointless endeavour - especially when working with a bigger sheet and trimming down to an exact fit is not difficult - and cheaper than getting a customised frame made.

Respectfully Lachlan, you have no idea what considerations unspecified here are involved, albeit you do seem to think you know it all. "Getting tied up in knots" as you patronisingly characterise my enquiry is me uncovering a problem I've never really encountered in over 35 years of darkroom work with FB papers. Not many other people on here seem to have come across this precise issue either, given the paucity of real insight from the thread. The issue has only come up because the nature of these images is that they cannot just be 'trimmed' to solve an issue. As I said above, I'll air dry the prints, which seems to produce more consistent results.

Ardpatrick · Feb 3, 2025

DREW WILEY said:
I don't fight the drying curl. I just let the prints fully air dry on fiberglass screens, emulsion-up. Then I place them under the weight of a big sheet of thick plate glass. That sufficiently flattens them for stacked storage purposes, until some are selected for permanent drymounting. Properly used, a drymount press is an excellent flattening agent.

Thanks Drew. That's my plan now. At least I can still use the glass sheets I bought for drying.

GregY · Feb 3, 2025

DREW WILEY said:
I don't fight the drying curl. I just let the prints fully air dry on fiberglass screens, emulsion-up. Then I place them under the weight of a big sheet of thick plate glass. That sufficiently flattens them for stacked storage purposes, until some are selected for permanent drymounting.
Properly used, a drymount press is an excellent flattening agent.

I agree Drew the drymount press is the ideal tool for the job.

Stretched paper? - Ilford 16x20 Multigrade FB not dimensionally stable?

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