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Minox Film Development

tank parts







Here is my procedure for developing Tri-X film (400TX) with EI 100-2000. Film is spooled in Minox cassettes, exposed with Minox subminiature cameras, and developed in a Minox Daylight Developing Tank using the Diafine two-step developer. Entirely without darkroom or changing-bag.

I use the quart size Diafine Two-Part Compensating Film Developer chemicals by BKA, 701 Corporate Woods Pkwy, Vernon Hills, IL., purchased from Calumet Photographic. The Diafine development process has two steps using two different chemical solutions. This process is not influenced by time and temperature, within reason (3 to 5 minutes, 70° to 85°F). However, temperature consistency is important to prevent deformation of the emulsion, so keep all chemical solutions at the same temperature (and this is one reason why I use water from a bottle instead of water from the spigot; another reason is that I use distilled water entirely). A stop bath is not needed to stop development because there is no development to be stopped; furthermore, with Diafine, a stop bath may be harmful to the emulsion.

With the Minox Daylight Developing Tank, I exchange fluids rather than agitate. This tank holds about 2 ounces - not much volume for agitation. So, I pour out almost a half ounce and immediately refill. This moves fresh chemical liquid over the film emulsion. The trick is to exchange enough liquid to keep active chemicals at the emulsion, but not so much that the film is not covered by liquid even for a moment. Liquid travels around chambers in the Minox tank to flow over the film emulsion from bottom to top and out the spout. For the developer and fixer chemicals, I pour that half ounce back into the working-solution bottle. For the water rinses and the wash-aid and Photo-Flo chemicals, I spill these into the sink.

Tri-X/Diafine provides extreme exposure latitude, preserving shadow and highlight detail, with the effect of compressing the 20+ stops of Tri-X down to 7 stops. Normally I use 1/100 second shutter speed for indoor photography. In bright light I use the grey (or green or yellow) filter and 1/1000 second shutter speed. In very low light I sometimes use my MeekFlashTM attachment. Otherwise I may set shutter speed according to light metering at 400ASA. Sometimes I bracket, taking shots two stops above and below these guidelines.

Loading Tank

Screw the spiral out of the tank in clockwise direction until it stops, then lift spiral with lid out of shell. Pull film out of the supply side of film cassette. Do not pull any film out from the take-up spool.

If you slit your own film there may be significant unexposed film after the last exposed frame, such that the first several exposed frames will not be loaded into the Minox tank and thus not developed. Cut at one [?] inch from the take-up spool. Save the remaining unexposed film as the fixer test strip, used in the HYPO step.

Invert spiral and place film cassette onto its tank chamber. 
Screw out the spiral until the screw aligns with the hole in the film. 
    The spiral has a small screw at the bottom where the film is attached. 
Slip film-end under spring and hook the hole over the screw. 
    Or, fold back end of film about 1/4" and slip under clip. 
    Film will "catch" on the screw and stay put. 
    Didn't catch? Fold the other way. 
Screw in the spiral to eliminate slack. 
    Do not pull any film out from the take-up spool.
Invert the shell and lower shell over spiral and into lid. 
    The spiral is already inverted.
Put a rubber-band around cassette compartment of tank
    to prevent accidental separation. 
Invert the entire assembly to upright position. 
Screw the spiral into the tank counterclockwise.
    As you turn the spiral, the film is pulled from the cassette
    and wound around the spiral, so expect some resistance.
    While screwing spiral into tank, there is resistance at first
    and gets lighter as film nears end, then suddenly resistance:
    STOP. Don't rip film off spool. 
Extend rubber-band to twist-loop over the top.
Put fixer test strip in tank spout area, held in place with rubber-band.

Develop Film

Development Procedure
Line-up the working-solution bottles, leaving spaces as indicated by subscript:
Loosen caps on all bottles. Smell HYPO for exhaustion (smells like rotten eggs, replace if needed). Let stand (about an hour) for temperature of liquids to stabilize.

Dust is the enemy of subminiature film (dust is big relative to the tiny size of film) and black&white scanning (infrared-dependent ICE is ineffective), so keep dust off film and out of chemicals.

Avoid bright light directly into top of tank loaded with film, especially with liquid.

All times can be a few minutes longer without harm.

Fill tank at center opening, not at the spout, until liquid appears at spout.

Note: fill tank procedure
 - fill tank from bottle (until liquid appears at spout)
 - tap tank lightly to remove air-bubbles from film emulsion
Note: tilt&fill procedure
 - tilt tank at 30° angle to remove about a half ounce
 - refill tank from bottle (until liquid appears at spout)
Load film into Minox tank. Put rubber-band around cassette compartment
      and twist-loop over top, to prevent accidental separation.
fill tank from DEVA bottle (five minute procedure)
 - each minute perform tilt&fill, returning liquid to DEVA bottle
 - then empty tank to DEVA bottle, tap tank lightly and invert thrice
fill tank from DEVB bottle (five minute procedure)
 - each minute perform tilt&fill, returning liquid to DEVB bottle
 - then empty tank to DEVB bottle
fill tank from AQUA bottle (five minute procedure)
 - each minute perform tilt&fill, spilling liquid to sink
 - then empty tank to sink; put AQUA bottle after HYPO bottle
fill tank from HYPO bottle (five to ten minute procedure)
 - place the fixer test strip in the pour-spout area
     use this to indicate when the fixer has cleared the film
     note the time film has been in fixer to the time film is cleared
       keep film in fixer for twice that time
     if total time in fixer exceeds ten minutes,
       use new fixer solution for next development
 - each minute perform tilt&fill, returning liquid to HYPO bottle
 - then empty tank to HYPO bottle
fill tank from AQUA bottle (one minute procedure)
 - after a minute empty tank to sink; put AQUA bottle after WASH bottle
fill tank from WASH bottle (half minute procedure)
 - after a half minute empty tank to sink
fill tank from AQUA bottle (ten minute procedure)
 - each minute perform tilt&fill, spilling liquid to sink
 - then empty tank to sink
fill tank from FLOW bottle (half minute procedure)
 - after a half minute empty tank to sink
Tap tank lightly and invert several times to remove all liquid.
Continue with Drying Procedure.
Development Procedure is done (total time under one hour).
Drying Procedure
I dry film after development with my Tank2DryTM device for dust-free film drying. Look at the cotton in the nozzle; replace if it looks dirty. Power-up the air-pump. Insert nozzle into the top of the Minox Tank. Park the assembly in a clean, dry location. Wait for several hours until dry. Store film uncut, emulsion on inside and put into clean large bottle cap, write date on cap, several in a zip-bag.

Refresh Working-Solutions
The developer and fixer chemicals are used over and over. All other chemicals are dumped after use. The Diafine developer solutions almost never go bad chemically. However, the solutions do get colored from dye in the film and some DEVA is absorbed into the film emulsion. If DEVA is less than half full, replace both DEVA and DEVB. Or, dump some of DEVB to equal volume of DEVA, then top-off each from storage-solutions. If HYPO smells bad or becomes too weak, replace. Replace or refill AQUA, FLOW and WASH as needed.

Chemical Disposal
Dye in the film is washed out by the liquids. The dye can stain a sink, so I dump liquids into a tub. If connected to a septic tank, take to a household hazardous waste collection facility. If connected to a sewer, everything can go down the drain because we're dealing with a very small amount of chemicals. Obey local laws.

Clean Equipment
Keep your equipment clean or suffer mysterious development problems.
Minox tank: shell, spiral, lid
Minox cassette: body, caps, spool
  remove caps (squeeze body at marks and gently lift cap)
  remove spool, separate from tape
  discard film fragment and tape
bottles, emptied or exhausted
eyedropper, measurement cylinder, etc.
While the Minox film cassette is inside the Minox tank, it is submerged in the several chemical solutions. The Minox cassette has felt pads where the film enters and exits. These felt pads need to be cleaned if you're going to reload with new film. Take care to not destroy the felt pads.
Rinse equipment under warm tap water.
Fill sink with detergent water as you would for washing dishes.
Wash as you would dishes, then rinse equipment and sink.
Fill sink with warm tap water and add one ounce from FLOW bottle.
Immerse equipment, let soak for one minute.
Remove equipment, one at a time, shake to drain.
Place equipment in a dust-free location.
Bottles and the Minox tank get an additional internal rinse with
  two ounces AQUA which can be used to rinse several bottles.

Copyleft Copyright 2009 John G. Derrickson     MeekFlash, SlitLoad, Tank2Dry, ScanDcam are trademarks of John G. Derrickson