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Roll Film, p. 3

July 24, 2013

COATING ROLL FILM — Many Options

Coating table set up with removable 10" x 36" x 3/16" glass sheets.

The glass is set on pieces of non-skid rubber fabric to keep it from slipping around during coating. I coat five strips of emulsion, let them dry, cut them up, and then take off the glass strips and fabric. The 2x4 ft. glass-topped table underneath is a perfect all around darkroom work surface. A string of red LED mini-lights is excellent illumination.

Coating tools: mix and match to taste.

It turns out that coating film isn't near the challenge we've all made it out to be. There are any number of options. The only goal is to get a smooth path of emulsion down at a consistent thickness. A puddle pusher, prepped with tape "risers" does the trick. An emulsion well of some sort helps, but just a bit. The best thing is to play and find out what works best for you. The nice thing is that all the play and practice work together. While you are perfecting your emulsion making itself, you are getting plenty of material to practice coating with. (And it will take practice.) It takes about ⅓ cup of emulsion to coat a strip of film approximately 5 x 30 inches. With a double recipe of Ammonium Bromide Plain Silver emulsion that comes out to ten rolls of 120 film.

One goal. Two different ways to go.

On the left: the film is clamped hard and dead flat along both sides of the glass sheet. A well and puddle pusher are pulled down along the left-hand side.

On the right: the two square wood dowels are separated the width of the puddle pusher, plus a fraction of an inch. Hold the puddle pusher in your working hand at the top of the sheet and pour emulsion in front of it. Immediately pull the puddle pusher forward between the guides.
Note: I used freezer paper to illustrate the emulsion. The appearance of a dried strip of emulsion is almost identical, except that a bromide emulsion is faintly yellow rather than white.

CUTTING STRIPS OF FILM

When the emulsion is completely dry, remove one wooden dowel. It will be glued to the plastic by the dried emulsion, so it's best to cut it off with a utility knife. Later, you can pull off the film and clean up the dowels. Clamp your cutting guide in place, top and bottom, and cut close along the edges of the guide. The emulsion will be thick along the selvages, so don't include those. I go back and forth on whether or not I prefer a cutting mat under the film (placed before you clamp on the guide.) A commercial self-heal cutting mat or just a piece of clean mat board will do the job. It makes the cutting easier and avoids scoring your glass, but it is an extra step. Art supply stores sell cutting surfaces and large individual sheets of mat board.

After you've cut the strip, and when you release the guide, the film will curl. A little experience will tell you the best way to deal with that. Try to handle everything with clean cotton gloves and as gently as possible to avoid fingerprints and scratches.

ROLLING THE FILM

Everyone's work space is different and requires slightly different strategies, but the basics are the same. You need clean and convenient.

Clamp a roll of backing paper down. One clamp goes on the paper at the head of the roll. Another goes at the end of the roll above the film spool, which is in place with a couple of wraps at the end of the roll. Then, take your strip of film and clamp it firmly so the emulsion starts about an half inch below the attachment point. When you cut the strip you included an inch or so of uncoated film.

Now, stretch out the film toward the spool and hold it in place with a weight or clamp.

Remove the spool-end clamp. Grab hold of the spool and pull the roll taut. Tightly roll the backing paper until it just catches the end of the film. If things move on you, your clamps aren't strong enough.

Turn over the backing paper and see where the numbers are. If your strip is shorter than the format, you can see how many exposures you'll get on that roll. Make a note.

This information will follow the roll of film from now until processing.

Roll up the film. The only "trick" is keeping the film from scooting sideways off the backing paper. You'll avoid this if you roll with two hands while pulling straight back from the head clamps. Roll tight. When you're done, you'll need to have the roll a little bit narrower than the ends of the spools. If it isn't, unroll everything and start over. When you get to the end, remove the clamps from the film, but not from the backing paper. The emulsion should now line up with the attachment point (more or less). Tape the film to the backing paper. I use white artist tape. Remove the last clamp and finish rolling. Fasten the leader end to the roll with a small piece of tape.

Put the film it its own bag or box and label it with a piece of tape. Record the recipe name, the date made, and how many exposures are on the roll. When you load your camera, transfer the information tape to the back of the camera.

In most respects our handmade and rolled film is treated just like commercial. An exception: our film shouldn't be stored or loaded and unloaded in bright light. A roll of commercial film is manufactured to be used once. When the machines are rolling the film, they manage to crimp the edges just enough to keep light out. When we re-use a roll of backing paper, the crimping is gone and light can pipe (i.e. leak) into the edges of the roll. You'll know light piping has happened when you develop the roll and the edges are black. This doesn't mean you have to have a darkroom to change film. Just be aware of the issue and experiment with your solutions.

Continued...



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