An eclectic collection of different topics mostly relating to my interest in photography. This reflects on my impulse to experiment, create, and develop my technique and new ideas. Some entries are meant as lab notes to record experiments and experiences or tutorials. I also try and cultivate other topics in photography. Please comment and I will try and respond. Find me on Flickr https://www.flickr.com/people/12328247@N00/
Print Flattening Revisited: Arbitrary Print Sizes
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Introduction
Fiber-based print flattening has a lot of suggested solutions, not all of them
have been very satisfactory to me. When I first started print fiber-based
paper in earnest I researched different suggestions on forums. They varied
from very simple to more complex. There are lots of solutions and many people
have their favorite method.
Hang the prints back to back (this was never very satisfactory for me).
Sandwich the prints between sheets of blotter paper that is weighted with
books. (I only got moldy prints from this.)
Vacuum bags. (never tried)
Use of watercolor tape (this lead to this solution
I am not here to challenge other techniques just share what works for
me.
The solution I settled on back in 2014 was based on a method that used water
color tape which has a water based adhesive. The idea was as the print
dried the paper shrunk and the taped edges held the paper in tension and
resulted in a flat print. One draw back was you cut the paper edges where the
tape was applied off so you needed generous margins. I couldn't find the
specified tape at the time but I thought about this more and decided to try
and clamp the edges of the paper instead. A very simple way to fabricate this
was to have Perspex or acrylic sheets cut to spec and use bull dog clips to
provide the clamping force. This method would allow anyone to fabricate
the parts without special tools or skills.
I built a version for 8x10 prints and then subsequently made increasingly
larger versions.
My experience with this method has been very positive. The prints come out
very flat on a consistent basis. One person
used it to flatten commercial prints; I was really happy to hear they liked the results. One person used wood and
wingnuts (also mentioned in linked posts) so this is possible as well. The
paper will get a slight curl in humid air over time as the paper and emulsion
swell differently. I find it offers no problem when mounting with PMA however.
The group that adopted it for the business added an extra step of storing the
print between two sheets of Perspex using the bulldog clips again. This keeps
it absolutely flat until mounted.
Some drawbacks and lessons are
A small risk of paper tearing. I had this initially with some Foma paper
but never since. (The user who used wing nuts and wood blocks experienced
this with larger paper.) I think the clamp force may be too high. One
benefit of bulldog clips is the force is limited and consistent.
The clamped edge of the paper becomes slightly glossy. I don't find this
an issue as the picture frame or matte will cover this. This is about
4-5mm typically.
Because I use Perspex the paper edges take 2-3 times more time to dry as
the bulk of the paper. This is because edge is clamped on both sides and
it takes a while for the water to wick out. This can result in edge
puckering if taken out too soon. (I have some ideas how to remedy this.)
The clamp blocks don't need to be so wide. I made them about 30mm wide but
would be fine at half this width and easier to use. Since they fill the
throats of the bulldog clips the positioning of the paper has to be made
more carefully. Done again I would change this.
Finally the system works well for standard paper sizes. Recently however I
have been cutting to different odd dimensions like 8x12", 12x12", 6x6",
9x9" etc. I find myself trying to make due with the parts I have then
drilling holes in clamps and backing boards. Generally a hassle with
unsatisfactory results.
(I should mention that we are firmly in DIY territory now and the method I
outline requires access to woodworking tools and the associated skills. (Update: I have now fashioned simpler version so if the DIY warning here has put you off try looking at this one...)
A Solution for Odd sized Prints
This final point was what became the forcing function for my next iteration.
One easy solution I have resorted to is to make my print on a full (uncut)
sheet of standard sized paper and then dry it in one of my standard sized
fixtures. I then cut the paper to size once dried and flattened. (I did this
on a 12x12" print printed on 12x16" paper for instance. This works and is
simple. However it wastes paper and fixer having to fix big blank areas of
paper.
I had two ideas in mind. This first would be to use magnets glued into the
clamps and using a backing board from perforated steel that has been painted
to prevent staining. The perforations would enhance drying and magnets would
allow continuous adjustment. Different lengths of clamping blocks would be
need to to add up to the different dimension differences. I imagine my prints
will probably be in fixed dimension increments of one or two inches so clamps
need to be made to different lengths to sum up to these dimensions.
I struggled to find a vendor that would take a small order cut to my specific
dimensions so I moved onto my second idea. I may revisit this in the future as
it seems quite elegant.
Update: I finally completed the perforated steel sheet version which can now be found here. So far it seems as good as the solution outlined here but simpler to build and to use.
My second solution was to use plywood routed with T-slots at intervals with
T-bolts used to clamp the blocks down. T-slots are slots in the shape of an
inverted T in a sheet of plywood. This allows a T-bolt to locking the slot. A
special router bit is available to makes these slots.
T-Slots
T-bolts have a special head that fits the T-slot in the narrow head dimension.
These T-slots are 9mm wide. The bolts are M5 threads (5mm shaft). I had to
order there off of eBay from China. I generally avoid buying directly from
China but could not find any local stock.
T-bolts
T-bolts in T-slots
I started with an objective to support up to 12x16 prints. I allowed for
an extra inch on all sides so I cut a sheet of 18mm plywood at 18x22".
(Sorry for the mixed units! I am an American living in Europe so have
become comfortable with both!)
I then routed T-slots at 50mm intervals. (I recently bought the DeWalt
cordless router and highly recommend it. Well made easy to use and no
cords.) I left an area about 8x10" unrouted in one corner. This allows
prints down to that size. If I want to go smaller the opposite corner can
support prints smaller than 8x10. This saved me some time and effort
with the slot routing.
Print Flattening Board with T-slots
Next I fabricated the clamps. I used 40mm wide 12mm thick plywood strips I
had left over from a prior project. I routed 4 slots for the T-bolts
offset from one edge of the plywood clamps. I made a number of 200mm (8
inch clamps). One of these I cut in half to made two 100mm (4 inch) strips
one of which I cut in half again to make two 50mm (2 inch) clamps. This
gives the ability to support print sizes to 50mm (2 inches) increments. I
may make some 25mm (1 inch) versions as well.
I made the slots off center to give me some flexibility in using them on
the edge of the board. All the wooden parts I painted with polyurethane
to waterproof them and keep the wood from staining the wet print.
I also glued sandpaper along edges on one side of the clamps and left it
smooth on the other side. This gives me the option of with and without
sandpaper. The idea of sandpaper edges is to perhaps allow better drying
of the paper edges by making it easier for moisture to escape. It will
also grip the paper better and this may lead to tearing of the paper. (I
used 400 grit wet/dry paper. Coarser paper may be better. Wet-dry paper
is formulated o be used wet so should not deteriorate with contact to
the wet prints. ) Experience will tell. (If sandpaper does not work I
may try felt instead.)
Clamp blocks with offset slots and sandpaper edging on one
side.
I needed something to tighten the clamps. Wing nuts would work
but I opted for using threaded inserts in wood handles. I milled a
simple pine strip and drilled holes for the inserts then cut them
apart.
Now with tightening blocks.
Finally, I found an odd sized print to try out. I used a recent 10x16"
print. On the two fixed edges I used my Perspex clamps and secured two
edges using bulldog clips. (One issue is the 18mm plywood is almost too
think for the clips and the Perspex clamps. I may route a thinner section
on these two edges on the back of the plywood to make it easier to apply
them.
Next I slid the T-bolts into the T-slots and the put the clamps over
the T-bolts and threaded the tighteners on the clamp slots. I used two
8" (200mm) clamps for the long direction and one 8" (200mm) plus a 2"
(50mm) clamp for the short edge to make my 10x16" image. I made each
clamp slightly shorter than the nominal dimension to allow them to fit
between blocks. I adjusted them for the small 3-4mm overlap on each
edge of the paper and then tightened them.
Print in Flattening Fixture
I was pleased so far the clamps are easy to use and adjust. Its is
easy to get them very tight and that might be a problem. However since
I continue to use the bulldog clips on two edges there should be some
ability for the paper to move if needed.
Results
After few hours to dry the print came out very flat and perfect. No
tears. The sandpaper seemed to work but even the edges under the
Perspex seemed to dry well. Perhaps the wood surface under was rough
enough to encourage drying. It is also possible the had plenty of time
to dry as I wasn't in a hurry. There is none of the glossiness on the
edges where the sandpaper was in contact though it is present in the
areas under the Perspex.
I am extremely pleased with the results. Next I will try a 12x12"
print.
Flattened print with clamps removed
Video
Here is a short 10 minute video showing its use and the results. (View on YouTube here... )
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