wiki:darkroom:chemistry:formulas:thornton_two_bath
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Barry Thornton’s two bath developer
Formula for two bath (divided) development.
Yields a compensating effect.
Preparations
Prepare stock solutions as described below:
Part A
| Water (@ 50 degrC), | 750 ml |
| Methol, | 6.5 gr |
| Sodium Sulfite, | 80 gr |
| Water, | to make 1000ml |
(This is a modified Kodak D-23 solution)
Part B
| Water (@ 50 degrC), | 750 ml |
| Sodiummetaborate | 12 gr |
| Water, | to make 1000ml |
As a substitute to sodiummetaborate, the following solution can be used (ref. Anchell)
Substitute
| Sodiumhydroxide, | 9.5gr |
| Borax (decahydrate) | 45.4 gr |
| Water, | to make 1000ml |
10ml of this solution substitutes 1gr of sodiummetaborate
Instructions for use
Develop the film according to the procedure below:
- Fill tank with part A.
- Agitate each half or full minute; frequency not very important
- After specified time, dump part A (back into bottle).
- Without a intermediate rinse, fill tank with part B.
- Make sure to dislodge air-bubbles from film surface (dunk tank into table-top or similar)
- Agitate sparingly; one agitation half-time through development should be enough.
- After specified time, pour off part B.
- Stop and fix as normal
Development times
Time per bath is approximately {3min, 4min, 5min} for films with ISO {50, 100, 400} respectively.
Capacity and shelf life
- Part A: should keep for approx. 12 month. Capacity is approx 15 films per liter.
- Part B: Capacity is approx 15 films per liter.
Notes
For lower contrast and finer grain, a plain solution of borax can be used (36 gr per liter) as part B.
Modify the proportion of sodiummetaborate in part B to adjust for the films SBR. Use {7gr, 12gr, 20gr} for {high, normal, low} SBR respectively.
wiki/darkroom/chemistry/formulas/thornton_two_bath.txt · Last modified: 2022/01/20 18:35 by henpe