Where did the colour go with BW process.

[Bob Carnie]

So have you every wondered why the prewash is always blue/cyan, but when you use no prewash the first developer is clear.

this is something that has perplexed me for over twenty years, maybe a stupid question but can anyone enlighten me to what is happening here.

 

[alienmeatsack]

I think it depends on your developer and what kind of developer it is.

I've noticed that Diafine A tends to take on the color of the dye used heavily without a prewash. I'll presoak my 120 Arista films just so my Diafine isn't bright green. And other developers just come out looking like they went in even without a presoak. Maybe it's something to do with the developer canceling the color of the dye in some developers formulas perhaps?

 

[Bob Carnie]

Ok so the developer is ID 11 were there is no prewash.

 

[removed account4]

hi bob

it is magic !

and i have poured a tray of AH dark blue into a clear tray of developer
it vanished ! ( i use ansco 130 to do this parlor trick )

 

[Vaughn]

Keep the lakes and oceans blue -- prewash your films!

 

[ntenny]

There's nothing special about blue, as far as I know. The old Efke films had a dye that came out in an attractive cherry red, and I think I remember reading that the dye in Tech Pan came out jet black.

But in general I haven't seen the dye disappearing completely in the developer. I mostly use HC-110 and PC-TEA as one-shots, and the used developer generally has the color of the AH dye, although over time it does tend to fade. Maybe it's only certain developing agents that do the job quickly.

Personally, I kind of like the ever-evolving colors of the Diafine A solution, by the way.

-NT

 

[jim appleyard]

Try Rodinal with either APX 25 (don't know if it works with other Agfa films) or Foma 100. A lovely shade of green with dump out of the tank.

 

[Bob Carnie]

Thats interesting, I am happy with my developer but wondering why no colour with D76 or ID11, maybe part of the components counter acting the AH>

Try Rodinal with either APX 25 (don't know if it works with other Agfa films) or Foma 100. A lovely shade of green with dump out of the tank.

 

[Gerald C Koch]

I think it depends on your developer and what kind of developer it is.

I've noticed that Diafine A tends to take on the color of the dye used heavily without a prewash. I'll presoak my 120 Arista films just so my Diafine isn't bright green. And other developers just come out looking like they went in even without a presoak. Maybe it's something to do with the developer canceling the color of the dye in some developers formulas perhaps?

The dyes used have no effect on development so presoak is a waste to time. Developer just has to work its color doesn't matter. In fact Ilford states not to do it with their films. AND the last time I used Diafine it specifically said not to presoak the film. Divided development depends on the dry film absorbing developing agent from the first bath. Presoak interferes with this and can lead to loss of film speed.

 

[Rick A]

My experience is the blue is neutralised in developer but not water. Sometimes it dissolves in the fixer and turns it blue, just depends on the film and developer I use.

 

[cowanw]

It's the same as DiDi 7.

 

[Gerald C Koch]

My experience is the blue is neutralised in developer but not water. Sometimes it dissolves in the fixer and turns it blue, just depends on the film and developer I use.

Some dyes are de-colorized by reducing agents such as the sodium sulfite in developers.

 

[MattKing]

In fact Ilford states not to do it with their films.

In fact, Ilford states that a pre-soak is not recommended with their films.

And quite recently, Simon Galley clarified further, that by "not recommended" Harman means, "not necessary", rather than "recommended against".

Pre-soaking works fine - just be sure to be consistent with whether or not you do it.

 

[lensmagic]

In fact, Ilford states that a pre-soak is not recommended with their films.

And quite recently, Simon Galley clarified further, that by "not recommended" Harman means, "not necessary", rather than "recommended against".

Pre-soaking works fine - just be sure to be consistent with whether or not you do it.

Thank you very much for clarifying that.

 

[ntenny]

Some dyes are de-colorized by reducing agents such as the sodium sulfite in developers.

Aha---if it's the sulfite, that would nicely explain the cases where I do and don't see the color persisting. No sulfite in PC-TEA or HC-110.

-NT

 

[Steve Smith]

So have you every wondered why the prewash is always blue/cyan, but when you use no prewash the first developer is clear..

Believe it or not, two days ago I processed a 120 film without pre-wash for the first time ever and wondered exactly the same thing. I usually use a few washes until the water doesn't come out blue but decided not to bother just to see if there was any difference in development (there wasn't).

Ok so the developer is ID 11 were there is no prewash.

I was using D76, so basically the same.

I was thinking about starting a thread here, asking the same question!


Steve.

 

[photo buddy]

To shed some light on your mystery the color in the prewash is backing dye, the color of the dye is PH sensitive that is to say some dyes go colorless at certain PHs and are colored at others.

 

[photo buddy]

Here is somthing you might try the next time you prewash keep some of the colored solution and add to it some acetic acid see if the color changes then take some of the solution and add some sodium carbonate or some sodium hydroxide see if the color changes. if you get a color change measure PH. I can also tell you different developing agents have different PHs as do the final solutions.

 

[Mustafa Umut Sarac]

I experienced more than the magic , I bought AGFA Isopan 120 film , 20 years ago and developed with d76. All the developer turned to cherry red and 5 hours later , it was the purest black green , after 5 hours again , it turned to water transparency. It was one of my first experience with developing films and my hat blown !!!

 

[Xmas]

Try Rodinal with either APX 25 (don't know if it works with other Agfa films) or Foma 100. A lovely shade of green with dump out of the tank.

Dark grey to black with APX400S a PET based film.

 

[Bob Carnie]

I think this answers my question

Some dyes are de-colorized by reducing agents such as the sodium sulfite in developers.

 

[Bob Carnie]

Great minds think alike? or would simple minds be more appropriate.

Dinesh this is not an opening for one of your purile comments.

Believe it or not, two days ago I processed a 120 film without pre-wash for the first time ever and wondered exactly the same thing. I usually use a few washes until the water doesn't come out blue but decided not to bother just to see if there was any difference in development (there wasn't).



I was using D76, so basically the same.

I was thinking about starting a thread here, asking the same question!


Steve.

 

[ic-racer]

So have you every wondered why the prewash is always blue/cyan, but when you use no prewash the first developer is clear.

this is something that has perplexed me for over twenty years, maybe a stupid question but can anyone enlighten me to what is happening here.

My Jobo dumps into the sink. So after the prewash there is still some colored water in the sink. Then, when the developer dumps out, I can see dramatically how the developer turns the colored water clear.

 

[CatLABS]

Bob,

Each film (or manufacturer) has its own dye type embedded it in. I used to like to think that this universal dye insertion was a way to tell you what films you are actually running in case you had no packaging. red, blue, green, black etc'... but in fact its just a part of the construction of the film, where PE when you need him?

As noted above the dyes get de-colorized/dissolved in the developer as part of its working process.

If you take your pre wash water which is colored, and drop just a few drops of developer in in there, you will see all the color vanishing before your eyes.
I used to do that demo at the first day of classes, it really is magic...

If you dont pre wash, the dyes get dissolved in the developer anyways as you run it, and you get clear developer when you pour it out.

 

[Rudeofus]

Each film (or manufacturer) has its own dye type embedded it in. I used to like to think that this universal dye insertion was a way to tell you what films you are actually running in case you had no packaging. red, blue, green, black etc'...

I believe that PE has stated a few times that these are sensitizing dyes. Remember, that AgBr by itself is only sensitive to UV light, and even AgI would only "see" blue or UV light. It's these special dyes that make an emulsion responsive to the parts of the light spectrum we want. After exposure these dyes are no longer needed.

As noted above the dyes get de-colorized/dissolved in the developer as part of its working process.

If you take your pre wash water which is colored, and drop just a few drops of developer in in there, you will see all the color vanishing before your eyes.
I used to do that demo at the first day of classes, it really is magic...

It would be interesting whether it is the alkaline property (as suggested by photo buddy) or the Sulfite ion (as suggested by Gerald Koch) which does the work. Next time I'll save some of that wash water and treat it with Sodium Carbonate and a pH 6 mix of Sodium Sulfite and Sodium Metabisulfite. I shall report here if nobody does that test first.