Discussion in 'B&W: Film, Paper, Chemistry' started by EASmithV, Apr 16, 2009.
How do I take negative BW film and develop it as a positive BW slide?
You develop it as normal, rinse/wash, then bleach it, then rinse, then pull it ou and hang it up to dry in light, then get it back onto the reel, develop again (no times for this, process to completion, ie you cant overdo it, just underdo it) and fix.
So I develop as normal, NO FIXER, THEN bleach & rinse with clorox, hang to dry, Re-spool, bleach until something happens in clorox, develop again in daylight until it looks good, and fix?
Not exactly, you don't use clorox, you don't hang to dry, but reexpose etc...
The whole process can be found here.
Btw, it's not the only method.
Are there any alternatives I can use for the bleach besides potassium permagnate and H2SO4? What about Lysol and stop bath?
The pure Lysol completely strips all emulsion off the film, developed or not.
I have often wondered if E-6 Reversal Bath will chemically fog a piece of b/w film, instead of pulling it out in the light. I have also wondered if plain-ol' pot. ferricyanide bleach would do the job of the Ilford bleach recipe.
Sure u can.
There are tons of recipes here in Apug.Look for them in the Articles section.
The separate E6 reversal bath should work fine after all all colour films are essentially B&W until developed in a colour developer.
The Ferricyanide bleach won't work as the Silver/Ferricyanide complexes formed are partially insoluble so don't wash out and the negative would partly re-develop along with the positive.
You should be able to use a colour bleach on it.
Hanging it to dry is easier, as you dont have to hold the reel and worry about re-exposing it to light for the correct time and making sure all the film gets enough.
You can't use a colour bleach as that will also remove the remaining un-processed silver halide as that you need to re-expose chemically or with light & develop to form the positive.
Our local photographic shop has a Tetenal kit for doing this. It's amongst a bunch of sale items and is going quite cheap. Does anyone have any experience of these kits?
You're thinking about a combined bleach and fix or when there is a bleach after last developing (followed by a subsequent fix)
The bleach doesn't remove silver halide, it converts metallic silver into bromide, (ie: the developed silver from the first bath), then second developer, develops the exposed silver (which is everything, bar what was developed in the first hence reversal).
The fix wont remove the second developed silver, but it will remove the first converted by the bleach silver.
Farmer's Reducer does remove the negative image. A ferricyanide bleach followed by a sulfite clearing bath also removes the negative image. The first development should be to high contrast. After the bleaching and clearing, the second development must be to completion, and Dektol or similar may be used.
That is the process in general, but I am not an expert at using it. There are some among us who are expert, aren't there, Jordan?
We make reversal chemicals for this process including chromate bleach.
A an image bleached in Fericyanide on it's own can be redeveloped even when no halide is added which is why it's not used in B&W reversal processes.
That's exactly what you don't want, the bleach needs to convert the silver into soluble silver salt that washes out of the image, If you convert the silver back to a bromide or chloride it will get re-exposed and re-develop with the positive.
Tetenal chemistry is extremely good, it should be worth buying.
The technique is called "reversal processing" and there are dozens of threads about it here and around the Net. A search will turn up lots of useful information here.
Agreed with Ian here -- for a bleach to be usable in B&W reversal, it must be able to completely solubilize the metallic Ag negative image without affecting the AgX positive image. This is not possible with iron(III) based bleaches, AFAIK. In practice the only commonly used bleaches for B&W reversal are dichromate- or permanganate-based.
Ok, a slightly different thing now-
Can you please look over this and tell me where I go wrong?
I'm going to reverse process Plus-X negative film in 16mm
First dev: HC-110 for 5 minutes
Stop bath for 3 minutes
Bleach in normal room light until it looks good (Farmer's reducer?)
Hold about 10 cm under a 60 watt incandescent light and re-expose on each side for about 30 seconds
Re-develop in normal room light with HC-110 until it looks proper
(I eventually want to try using Caffenol for the second developer)
Fix 5 min
With plenty of rinses of course
A few problems I notice, with my limited knowledge of photo chemistry:
1. You want to bleach before re exposing, not while re exposing.
2. Mr. Grant has pointed out that ferricyanide bleach will not work for this, as it does not remove the bleached silver of its own accord like the permanganate bleach listed in the Ilford recipe, but instead "marks" it for removal by fixer. If it is not removed before you re expose and re develop, the process will not work.
3. Farmer's reducer is ferricyanide bleach mixed with the main ingredient in fixer. If you use Farmer's Reducer as your bleach, it would make sense that you will also remove silver that you intend to re expose.
4. How are you going to handle the remjet layer?
Finally, what are you aiming to achieve? Saving about 18 cents per foot in processing costs ($18 per $100 feet)? If this is all, consider the volume you will be shooting and the time, chemical costs, and such that you will spend on this to determine if it is really worth while. If this is just a fun experiment, have at it, but if you intend to save a whole bunch of money, I would not count on it.
Remjet? Is that like anti-Halation dye? If so, doesn't that wash out with the first developer?
Not to be thick, but what is the difference between the bleach and clearing bath? Is the clearing bath just to remove all the bleach?
The clearing bath removes the bleach (or makes it possible to be washed away, perhaps). The Ilford data sheet talks about this. You really need to read some data sheets on the process to understand it better, IMO.
The remjet coating is put onto the base side of motion picture film. It works as a shield for the base side; to absorb the minor abuse of being run over the camera internals at high speed. It also works as an anti-halation layer and to cut down on static electricity due to the motion of the film. The base side of your film will not be glossy if your film has this coating. When processed at a movie film lab, I believe that the coating is removed prior to development. It does not come off with a simple presoak. There are ways to remove it if processing at home, though I have never looked that deeply into it myself.
According to Kodak:
• Remjet, a removable jet black layer, is the coating of carbon black particles in a water-soluble binder on the bottom of the film. It has four purposes: antihalation, antistatic, lubrication, and scratch protection. The remjet carbon layer is also conductive and prevents the build-up and discharge of static charges that can fog film. This is especially important in low relative humidity environments. Remjet also has lubricating properties. Like the supercoat on top of the emulsion, remjet resists scratching on the base side and helps transport the film through cameras, scanners, and printers.
Remjet is typically found on motion picture film which must go through the camera at a high rate of speed. I don't think Ilford uses it, even on their Motion Picture films. Kodak does use Remjet on Kodachrome, the only still film that uses it today.
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