The paths are many, no matter how high the mountain. The best path is the way you make it. Take your path up the mountain
Contact processes require negatives as large as the finished print. The iron processes, being significantly less sensitive to light that the silver process, require big negatives.
Carbon, gum, platinum, cyanotype, etc. are contact processes. The film and sensitized surface are in ‘contact’ during exposure. The exposures are made using much brighter lights as well as, typically, longer exposure times.
The decline in film use has affected the supply of large film (sheet film) more than the roll films (135, 120).
In overview, to make an 11×14 print, as an example, we need an 11×14 negative. Supposing we begin with a smaller negative, say a 135, or 4×5 negative, we need either a ‘DIRECT” negative, or an intermediate POSITIVE. These are intermediates in the process. They will reduce some of the original technical quality introducing generational artifacts – altered contrast, sharpness, grain, and such.
The problem: available materials for large negatives is limited. Litho type films are designed to make dense high contrast negatives suited for offset, silk screen, etc. ink print process. They do fine for screened negatives, but not as well for continuous tone negatives. They provide high density, but limited shadow, or highlight values.
Need: place density as well as adjusting contrast using high-contrast emulsion.
Problem: dilute developers exhaust rapidly, the lith films exhaust developers quickly, these factors can result in mottled, uneven development, or inconsistent process results between test and final product
Need: replenish often. work quickly. don’t take 2 hour breaks. measure amounts of chemical for use in small batches. Old dye transfer adage: mix for 4, develop 3.
Schematically, the direct method of enlarged negative is the best – it introduces the fewest process artifacts – lens, chemical, emulsion deficiencies. That’s N to N. The worst way is 2 stage one from: original to interpositive, to enlarged negative (internegative). If you have a good enlarging system, enlarge the interpostive, otherwise make a contact positive, then enlarge that. With an enlarged positive, make a contact negative to print from.
- Kodak SO-132 (4168) direct duplicating film
- TMAX Reversal
- Kodak Professional Copy Film (4125)
- Kodak Gravure Positive (4135)
- Kodak Commercial Ortho (Type 3)
- Ilford Ortho Plus
- Arista Whatever Lith
- TMAX Reversal – of some sort
- Digital Film Print – like Pictorico — This is the most widely used means of producing large film negatives for contact printing.
There are few silver intermediates possible, even the digital ink method films are sometimes unavailable, with few people doing enough volume to keep the companies filling the dwindling need. Once large scale coating companies have converted to production of employee ID badges as a larger, more consistent revenue source.
Control of contrast is done by monitoring shadow exposure in the positive. The flash is done for 20-60 seconds for lith film. The second, bump exposure uses an OA safelight 3 feet from the film. This exposure adds highlight density, seemingly lowering contrast of the lith film. The process of control by ‘flash’ and ‘bump’ was common in litho shops where control of dot amount and density was being managed under widely ranging original.
The inter-positive will look dark and flat. The internegative will have to be higher contrast. If the internegative film is Ilford Ortho Plus it should be developed in D-19, D-11, or some other higher contrast developer.
Ilford Ortho Plus
Ortho Plus is my choice for achieving continuous tone enlarged dupes. It doesn’t come in as large size as Whatever Litho, but it is easy, reliable, well document product to use. With PQ Univerasl, and D-76 good intermediates can be made from common original negatives. Ones that could be printed on normal grades of paper can be duplicated for use in cyanotype, gum, and similar alt-processes. Adding D-19, or Phenisol to the cupboard means you can cook negatives for Platinum/PtPd processes. Phenisol at 1+4 can get a negative with 1.8+ gamma.
A changeable target. This is a re-badged something litho film designed for screened film — dots as in magazines or newspapers – these are meant to be black, or white. A binary thing that codes grey by relative sizes of the dots. Litho developer, that A+B stuff, is the pathway to high contrast negatives/positives.
The paths of lith.. dots, or tones. 2 tone, or continuous tone. Litho film is inexpensive film sold in large enough sizes to serve as negatives for contact process such as gum, platinum, collotype. Getting the film to produce gradual, long tonal scale negatives is difficult – chemicals, and exposures must be managed closely- not easily done for the casual or occasional lab worker. Most people use dektol since it is probably already being used as their paper developer. Dektol diluted up to 1+6 is a good enough standby to be considered a standard trial point.
Without direct dupe film, nor ready reversal chemistry available, I use the 2 step approach to dupe enlarged negatives. The testing I’ve done with reversal chemistry has not been as fruitful as using the longer, standard of 2 steps.
Step 1: make positive from original
Step 2: make negative from the step 1 interpostitve
My interpositive film is Ilford Ortho Plus. It comes in 4×5, & 8×10, so makes good positives for use in enlarger (4×5) or as contact positive for final negative. The step 2 film is either Ilford Ortho Plus, or Arista Ortho if a negative larger than 8×10 is needed. The ortho film is also useful for higher contrast effects than can be gotten using the continuous tone Ortho Plus.
Light Source Start Point
I have several light sources available, with the Beseler 45 being an easy to use favorite enlarger. It is hooked up to an fStop timer and exposure meter. Additionally, I use a light meter made by Darkroom Automation to set light levels. In the table below, “dupe neg exp standard,” the DA reading with the enlarger configured with a 150mm lens wide-open, set 23 inches away from baseboard, the meter reads 9.10. Changing the height of the head, and adjusting the aperture to 9.10, requires the indicated Exp Adj. This knowledge permits me to test one setting, and apply results to others. This process allows me to get to high quality dups with less wasted material.
- Step 1: 9.51 seconds exposure. developed in PQ universal (1+9) 4 min.
- Step 2: 4 seconds exposure. developed in D76 (1+1) 8 min.
- alt Step 2 (arista ortho): 12 seconds exposure. developed in RLC (1+4) 11 minutes.
- alt Step 2 (arista ortho): 14 seconds exposure. developed HC-110 (1+30) 5 minutes.
The step times above are based upon the enlarger configure as above. After getting the enlarger set, I stop the lens down by 2 more stops. My exposure times are with the lens set from 2 to 3 1/2 stops down from wide open (DA reading of 9.10).
My way of working is just that, my way. There are more possible ways, however, what I’ve presented above will get you into control of your way. Following are even more details on paths you can take to making your own enlarged/dupe negatives.
Low Contrast Developers
Off the shelf:
Rollei RLC developer for technical film materials with very steep gradation, which produces normal contrast negatives which will print easily.
Mix From Scratch
Paper as the interpositive or duplicate negative. Slavich has a very thin single-weight paper suited for interpositives, or use RC paper from any supplier. RC paper doesn’t present as much texture to print through as does fiber paper. The best fiber paper is one that is very thin, hence the recommendation for using Slavich Unibrom SW (grade 2)
The real way, the common pathway of making large negatives is by digital negative route. Shoot digitally, or scan film, then output to transparency film using a digital printer. This can be using altered inks, special software RIP, or specially developed methodologies sold by such places/people as:
- HP DesignJet Z3200 using black and green inks. promoted in 2011.
- Easy Digital Negatives – Peter Mrhar
- Ron Reeder
- Dan Burkholder
- Harrington – QuadTone RIP (basis of most digital neg methods. suited only for Epson printers (pre 2016 models))
- PIEZODN – Cone & Blackwell – NOTE: check to see if your printer is supported. (post 2016 models)