paper shrinking problem, don't know what to do any more ...

Xandros · Aug 13, 2010

Hi all,

I have a big paper shriking problem since the beginning of my gum printing activities (I'm only a beginner) 1.5 years ago.

Classic problem I would say, after the first coating/developing/drying, once I try to re-register the transparency negative with the paper, I get about 1mm off for print 18cm in width (that's 0.04 " off for a 7 " print).

It's enough to make the print to look blurry after the second coating.

I tried pre-soaking the paper in different manners, tried pre-soaking and drying twice before the first coat, tryed let it soak a full day, no avail.

Tried different papers, BFK Rives, Somerset, Lanaquarelle, Montval, Hahnemuhle ... same issue more or less.

In the summer, when the temperature is about 25°C and 50% relative humidity, I get 1mm off on a 18cm print (A5) and in winter when it's more like 20°C and 60-70% humidity, its a bit better but still 1mm off for a 29cm print (A4). It doesnt even make sense to try bigger prints ...

What can I do about this ? Pre-shrink 10 times ? Print on wood instead of paper ?...

Thanks for your ideas & help in advance !

Steve Smith · Aug 13, 2010

Not sure about your specific problem but at work we screen print onto polyester. We make sure that the material has done all of its shrinking before we start to print otherwise we would not be able to register print layers to each other.

Is it the paper itself which is shrinking? If so you should be able to come up with a process which will stabilise it before you start coating.

If it's the coating itself which is causing the shrinkage though, some sort of backing layer may be the only solution.

Steve.

Xandros · Aug 13, 2010

How do you do thie with polyester ? you mean you print on polyester or you bind the paper to polyester backing ?

Steve Smith · Aug 13, 2010

We heat treat polyester at a slightly higher temperature than we are going to cure the ink at. It just goes down the drying line a couple of times before printing at about 5 degrees (C) above normal temperature.

Steve.

Loris Medici · Aug 13, 2010

Xandros,

Still pre-shrink, and:

Try with a thinner gum/pigment emulsion mix. E.g. if your gum is 1+2 (gum+water), then use it as following: 1+1+0.5 (or 1) (gum/pigment+dichromate+water)... A too thick gum layer will end up shrinking paper proportionally to image. (Darker = thicker parts will shrink more...)

and

Wait a little longer in the first layers (to let the paper dry to the touch), wait less (still has to be dry to the touch, though...) with the subsequent layers. (Check intermittently using the negative, and start to print when the images align perfectly...) Dampening the back of the paper with a moist sponge may help...

and/or

If still everything fails, print the negatives for subsequent layers by shrinking the image according to the image size on paper. (Few trials will give you the shrinkage ratios on each step...) In other words; print the first negative, print the layer using it, measure the image size, and print the second negative to measure. (You'll workout the ratios, and be able to print all three or four negatives together later...) Pay extreme attention to the grain direction of the paper, though; shrink ratios vary according to grain direction...

also

You may opt to affix the paper on a dimensionally stable support using removable dry mount tissue such as this one. But you need a dry mount press to do that... (This is Keith Taylor's method, mentioned here.)

Hope this helps,
Loris.

Xandros · Aug 13, 2010

Thak you for this explanation Loris !

Yes i'm using 1+2 gum. I'll try with more water, but I may be mistaken but I have the feeling that it will only make the layer less pigment-dense (hence more layers needed) and take more time to dry. How could this affect the shrinking ?

For the second part, you mean to print first layers when the coating is extra dry, and the next ones when the paper is still a bit damp on the back ? (not fully skrinked to dry size)

I didn't think of making multiple negatives, but yes it seems to be the easiest option if the shrinking is consistent.

I have read this method already a few months ago but do not have such kind of hardware ...

2F/2F · Aug 13, 2010

Do you have "The Book of Alternative Photographic Processes" by Christopher James? I believe it lists a few different sizing formulas to try if plain water isn't working for you.

Loris Medici · Aug 13, 2010

Xandros,

Yes, the water will thin the emulsion, but that may work/help if you're currently printing an unnecessarily thick layer. The thicker the layers are, the more shrinks the paper. (Proportional to image that is - look at the back of the print, you'll probably see the embossed image...)

I don't mean extra dry, but considerably drier than the subsequent layers. E.g. if you're waiting 30 minutes before printing, wait 10-15 for the first layers, then more for the next ones... And if the paper shrinks too much, you can always slightly moisten (not wetting! just moistening...) the back to relax the fibers.

A good sizing helps in stabilizing paper strenght. Do you size after pre-shrinking? (If not, lay a hardened 3-4% gelatin sizing before the first layer.)

Loris Medici · Aug 13, 2010

Also, print the light colors (yellow / magenta) first. The paper usually doesn't change dimension much after the first couple of layers... Since the dark / contrasty content (cyan / blue / black) will be put on paper after this stage, you won't notice much blurring etc...

Colin Graham · Aug 13, 2010

Try to always hang the sheets from the same corners when drying, especially big prints.

Hexavalent · Aug 13, 2010

Xandros said:
Hi all,

I tried pre-soaking the paper in different manners, tried pre-soaking and drying twice before the first coat, tryed let it soak a full day, no avail.

Are you pre-soaking in hot water? For troublesome papers I pre-shrink twice, using hot (130 F) water, letting the paper sit for 1/2 hour, dry, repeat, then size. After that, I rarely see any shrinkage problems.

-Ian

Xandros · Aug 13, 2010

You're right, I'm coating the paper with alum-hardened gelatin after pre-shrinking.

I only print with black pigment.

Ian, yes I let it 1 hour in hot water, fully dry, 1 hour in hot water, dry, size, dry, coat, ...
What paper are you using ?

Loris, first you said

"Wait a little longer in the first layers (to let the paper dry to the touch), wait less (still has to be dry to the touch, though...) with the subsequent layers."

and now

"wait 10-15 for the first layers, then more for the next ones..."

Isn't it the contrary of the first statement ? or did I miss something.

I don't know, I am thinking of trying a first gum/dichromate layer only without any pigment, the paper will be less pure white after that but maybe it will help, what do you think ?

Loris Medici · Aug 13, 2010

Oops! Yes, I wrote it in reverse; the first one is true... E.g. Wait 30mins for first layers, 15mins for subsequent ones. Sorry for the confusion...

Hexavalent · Aug 13, 2010

Xandros, I managed to salvage some otherwise useless Arches Aquarelle by double-shrinking. When I'm feeling rich, I use 300 lb. Canson (it's almost cardboard).

I harden my gelatin sizing with formalin or glutaraldehyde - it's sturdier than alum hardening, which is prone to swelling. For cheaper papers like Cotman, I sometimes size twice, first with a very dilute mixture .5 - 1% gelatin to 'lock' the paper fibres, and then, after drying, size again with 3% to provide a 'top-coat'.

-Ian

Colin Graham · Aug 13, 2010

Usless Arches Aquarelle? Maybe it's a climate thing, but the 140 lb works perfectly here in western Washington, at least as stable as Fabriano EW with a single shrinking.

Hexavalent · Aug 13, 2010

Colin Graham said:
Usless Arches Aquarelle? Maybe it's a climate thing, but the 140 lb works perfectly here in western Washington, at least as stable as Fabriano EW with a single shrinking.

I should have noted: "Useless" as it was bad batch, either flawed in manufacturing, or in storage - uneven wetting, curl etc.,
Turns out there was a good reason for it being on sale cheap.

-Ian

Xandros · Aug 13, 2010

Thanks for the precision Loris

Ian, I use cold pressed 140lb Lanaquarelle watercolor paper for now. The gelatin sizing formula I use (found somewhere) is about 4-5% gelatin, 10% alum. I don't have any formalin or glutaraldehyde here unfortunately, so maybe I should try two coats ?

the ambient humidity seems to be meaningful indeed. i'm performing some size measurements with a test paper strip right now ...

Loris Medici · Aug 13, 2010

In any case, feel free to bend the figures, OK?

Xandros said:
Thanks for the precision Loris

PVia · Aug 13, 2010

Xandros, how are you registering your prints? Just curious...

Here, I use Fabriano EW, both hot and soft press and have no problems with small sizes (up to 8x10) without preshrinking or sizing. I've been able to do the same for a 9x14 print as well - see this link:http://www.flickr.com/photos/viapiano/4667167861/in/set-72157624234247830/

Rives BFK shrinks a lot more than the Fabriano, but I rarely soak any piece longer than 5 minutes in lukewarm water. Humidity is usually 40% and below here, and temps are 70-95 degrees F.

Try some Fabriano, without shrinking and without sizing...you may be pleasantly surprised. I should mention that I use 1 gram of tube pigment to 9ml of gum, and then use that mixture 1:1 with the dichromate. I register with pushpins.

Xandros · Aug 13, 2010

I register with pushpins.

BFK is unusable to me, shrinks way too much. Im not sure I have that Fabriano EW here, not all papers in the world are available unfortunately

Is it Artistico EW 140lb (300g/m) ?

I'm making some tests right now with a strip of paper, and after 2 times 1hour soaking in hot water + drying, the lanaquarelle paper didn't move at all. i'm proceeding to first gum coat now.

Loris Medici · Aug 13, 2010

A last note: Try to keep your workplace at same temperature and humidity. Same for the place that you dry your papers. (Not necessarily the same conditions as the workplace, but it has to be a stable environment...) If you keep your paper somewhere else, bring some to the workplace in advance, to let them stabilize under working conditions... (Consistency is very important and one of the keys to success.)

Loris Medici · Aug 13, 2010

Xandros said:
...
not all papers in the world are available unfortunately
...

Where are you Xandros? (Name suggest Greek origin, are you in Greece or Cyprus? Actually a silly question, since there are Greek people all over the world; Continental Europe, U.S.A., Australia...) We have all the variants of Fabriano "even" here in Istanbul, Turkey. Therefore I'm sure you'll be able to find Fabriano in your part of the world, if you aren't in a extremely remote place... To me it's the best paper for gum! (Any variant is good - given you like the base color and texture of the variant in question, plus it's >= ~300gsm...) Try to source some...

Xandros · Aug 13, 2010

It's a nickname, and I'm not greek but Russian origin

But, I'm in Brussels, Belgium. There are some fabriano papers here at the local shops, but not all of them. It looks however that the same paper somehow works without shrinking for some people but not for others. There is something I must be doing wrong Thanks for all your help anyway !

I'm continuing my test strip experiment and will let you know the results ...

Loris Medici · Aug 13, 2010

BTW, in order to prevent any probable misunderstanding, I'm talking about Fabriano Artistico (that Paul mentioned) specifically. (Traditional White / Extra White bases with hot press / satin / cold press surfaces...) Fabriano 5 also works well, FWIW. But Artistico is what you really want!

Regards & good luck,
Loris.

Xandros · Aug 13, 2010

Thanks, will have a look indeed !

paper shrinking problem, don't know what to do any more ...

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