Developer Dilution confusion

[marsbars]

I am playing with the idea of processing my own films soon but am confused about dilution. I am looking at starting with Ilford DD-X that comes in a liter bottle. I understand that it is a one shot at 1:4. Now my confusion comes from the literature that states that a 1L bottle will develop 16X36exp rolls. Now is that dependent on tank capacity? This leads me to the next question. I am planning on starting with a single reel tank to get the hang of it. Now if I decide to develop 4 rolls in an afternoon then would I mix up only enough to do that? Or does one mix the whole L with 4L of water?
I am such a n00b that I am really confused.:confused:

 

[MattKing]

Take what follows with a bit of a grain of salt, because the capacity recommendations from the manufacturers are sufficiently conservative as to leave a little wiggle room, and because there is a small range of volumes of chemistry that is sufficient to work in each tank.

When you determine how much developer (at working strength) to use in a tank, you have to be careful of two things:

1) that there is enough volume in the tank to ensure the film develops evenly; and
2) that there is enough active chemistry in the working strength developer to ensure that the developer doesn't exhaust itself before the job is done.

Now with the DDX and the instructions you have been given, it appears that 1 liter of stock will do 16 rolls, so you need at least 62.5 ml of stock per roll. If you were to dilute 62.5 ml of stock 1:4, you would end up with 312.5 ml of working solution of developer. If the tank you use requires that amount or more {EDIT} if you use the amount of working solution necessary, the developer will be able to do its job and the results will be fine{End EDIT}.

The downside of having a tank that requires more than that 312.5 ml, is that you won't be able to get 16 rolls of development out of the 1 liter bottle at 1:4. In order to maximize the yield of a single bottle of stock, you may want to dilute that 62.5ml of stock a bit more (say 1:4.5) in order to get enough volume of working solution to suit the tank.

If the tank holds less than 312 ml, you will need to change your dilution to something like 1:3.5, because there must be at least 62.5 ml of the stock in the tank for the developer to do its job.

If you end up increasing the dilution/decreasing the concentration, you may have to adjust your time up a bit. If you end up decreasing the dilution/increasing the concentration, you may have to adjust the time down a bit.

Those with more experience than I with DDX can give you a better idea as to how much "wiggle room" you can count on.

Hope this helps.

Matt

 

[srs5694]

Now my confusion comes from the literature that states that a 1L bottle will develop 16X36exp rolls. Now is that dependent on tank capacity?

Yes, although you may be able to fudge that -- say by diluting more than the manufacturer recommends, as MattKing describes. His post has given some good advice (although I think he meant "If the tank you use requires that amount or less you are fine" rather than "If the tank you use requires that amount or more you are fine"). I've not seen much discussion that suggests that people try to get exactly n rolls of film out of a bottle of developer by tweaking the dilution, though. Rather, I think most people just use one of the recommended dilutions and then, when the bottle runs out, either discard whatever fraction remains or combine it with developer from the next bottle. Used in this way, your cost for chemicals goes down if you use a tank that requires less solution.

Stainless steel tanks are generally best in this respect, although they cost more up-front. I've got a Russian plastic tank that's almost as frugal as my stainless-steel tanks (in fact, I use 250ml for a single roll in either tank, although there's almost no margin for error at that volume with the Russian tank). My AP-brand plastic tank requires 350ml per roll, IIRC.

The danger to using smaller-capacity tanks comes when you try to use a very dilute developer; there'll be fewer moles of developing agent in a smaller tank, so if the developer is diluted to the point that there's barely enough developer to do the job in, say, a 350ml tank, using the same dilution with a 250ml tank could become an issue. This is seldom a problem with common developers and dilutions, although it could be with some. (I've seen claims that using XTOL at greater than 1+1 dilution can cause problems with some films, for instance.)

This leads me to the next question. I am planning on starting with a single reel tank to get the hang of it. Now if I decide to develop 4 rolls in an afternoon then would I mix up only enough to do that? Or does one mix the whole L with 4L of water?

As I posted in another thread, I see no reason to favor a 1-reel tank unless you think you'll never want to process more than one roll at a time. You can always process fewer rolls (with less solution) in a bigger tank. Past a certain point it'll get awkward to handle a bigger tank, but that's not likely to be an issue when moving from one-roll to two-roll (35mm) tanks.

To more directly answer your question, with most developers you dilute from a stock solution or from a liquid concentrate to the working dilution just before use. So if you had enough rolls that you had to do them in more than one pass (or if they required different times, thus necessitating multiple passes), you'd normally dilute the amount you need for each pass just before doing it. You could, of course, dilute the total amount and then measure it just before use, but that would leave the developer diluted for longer, and developer that's diluted for use will normally go bad more quickly than the stock or concentrated form. I doubt if this effect would be significant for most developers, assuming you did the rolls back-to-back, thus using the amount you mix within an hour or two. Still, it's not much more work to dilute immediately prior to developing each batch vs. diluting it all beforehand.

 

[MattKing]

Yes, although you may be able to fudge that -- say by diluting more than the manufacturer recommends, as MattKing describes. His post has given some good advice (although I think he meant "If the tank you use requires that amount or less you are fine" rather than "If the tank you use requires that amount or more you are fine").
....

The danger to using smaller-capacity tanks comes when you try to use a very dilute developer; there'll be fewer moles of developing agent in a smaller tank, so if the developer is diluted to the point that there's barely enough developer to do the job in, say, a 350ml tank, using the same dilution with a 250ml tank could become an issue.

srs.....

Actually I did mean it the way I posted it, and I think that the second part of your post shows the rationale (in a particularly clear and cogent way, I might add).

If it helps, you can say it as follows:

If one uses working solutions at the same dilution, bigger tanks end up using more of the original stock solution.

Personally, I use HCC110, which is far more concentrated than DDX.

Clearly, what we really need is Donald Qualls posting to this thread. He doesn't seem to post here anymore, but IIRC he has great expertise at getting the most out of every milliliter of developer.

If Donald is watching, best wishes!

Matt

 

[marsbars]

I can now see the pros of using a 2 reel tank but now the next question. I have heard that the plastic ones are easier to load than the stainless ones but the stainless ones last longer. Is that really such an issue or not. I like the idea of a tank that will outlast my lifetime if I take decent care of it. I am not opposed to spending a little more on a better tank.

 

[MattKing]

Marsbars:

If you search through the archives here, you are likely to see arguments on this issue that are almost religious in their fervour.

My take on the matter - the high quality steel reels are harder to learn to load, but assuming you are able to do so, they work better and, if you treat them reasonably (don't drop them) will last forever.

In my case, I think steel reels work great for 35mm, but I struggle with 120.

If you are thinking of going to 4x5, Jobo offers alternatives for all three.

Matt

 

[srs5694]

srs.....

His post has given some good advice (although I think he meant "If the tank you use requires that amount or less you are fine" rather than "If the tank you use requires that amount or more you are fine").

Actually I did mean it the way I posted it, and I think that the second part of your post shows the rationale (in a particularly clear and cogent way, I might add).

If it helps, you can say it as follows:

If one uses working solutions at the same dilution, bigger tanks end up using more of the original stock solution.

I agree with your latter phrasing; I just don't understand why you'd say that "you are fine" (which, in context, I take to mean you'll get the claimed 16 rolls or more out of the 1l of developer) when using tanks that require more than the 312.5ml solution you computed. It's the other way around, as you state here. Obviously you meant the correct thing; I just interpreted your sentence in a way that would necessitate "less" rather than "more," and I'm still not clear on how "more" would be correct in that context. Maybe I'm just too tired right now. In any event, it's moot; I think it's been expressed very clearly by now....

I have heard that the plastic ones are easier to load than the stainless ones but the stainless ones last longer. Is that really such an issue or not. I like the idea of a tank that will outlast my lifetime if I take decent care of it. I am not opposed to spending a little more on a better tank.

As MattKing says, this is a matter of personal preference that verges on the religious. My own experience is that plastic reels tend to jam up partway through loading, particularly in humid weather. (Even a little water makes them almost impossible to load.) I'll also add that if you go with stainless steel, you should be sure to get a good brand of reel. Personally, I like Hewes reels (which are sometimes sold under other brand names, confusingly). These reels are made from slightly thicker metal, and their 35mm reels have two prongs at the center of the reel. You attach the film's sprocket holes to these prongs, which automatically centers the film. Other brands have clips in the center of the reel, which makes it harder to get the film centered. The result can be loading difficulties -- the film can "jump" grooves, resulting in the film touching itself and areas of no development in the final roll. The downside to Hewes reels is, predictably, that they cost more than most other brands.

 

[MattKing]

marsbars:

srs5694 is right - my use of "you are fine" definitely invited confusion. I was of course referring to whether or not the developer would do its job correctly, and not whether it would process as many rolls as you might want. This does, however, highlight the difficulties and benefits of learning through online forums - on the good side, you have received input from two photographers almost 3000 miles apart, while on the bad side, we (I??) might have ended up confusing you thoroughly!

For that good reason, don't hesitate to ask for clarification, if there is anything in an answer (in particular my answer) that requires it.

By the way, I have now edited my earlier post, to try to avoid the earlier confusion.

Matt

 

[srs5694]

re: The "more" vs. "less" thing: It just occurred to me that MattKing and I were thinking in two different ways, which may be important to make explicit for marsbars' benefit:

1. I was thinking in terms of the volumes required, at the specified dilutions, to get the specified number of rolls (16) out of the product (1l of Ilford DD-X) using the specified dilution (1+4). To get 16 or more rolls, you need a tank that uses 312.5ml or less of solution. This ignores what I believe MattKing was thinking about....
2. MattKing was thinking in terms of the required capacity of the developer to completely develop a roll of film. If the claim of a 16-roll capacity is based on this, then you'd need to use at least 312.5ml of solution to be sure of complete development.

I don't know in which way Ilford means its "16-roll" claim. My assumption (perhaps a mistaken one) is that products marketed to hobbyists would use meaning #1; after all, the manufacturer doesn't know how big any individual's tank is, and so would create recommended dilutions that would work well even with small-volume tanks and number-of-rolls claims that are reasonable given typical tank capacities. It'd certainly be disastrous to the product's reputation if people tried to develop rolls in smallish (say, ~250ml stainless-steel) tanks using the recommended dilution and encountered failures.

I'm not very familiar with Ilford DD-X, but Ilford does have loads of information on their Web site. You might be able to find a document there that clarifies this matter.

Edit: I wrote the above while MattKing was writing his latest reply; I didn't see it until after I posted mine!

 

[MattKing]

re: The "more" vs. "less" thing: It just occurred to me that MattKing and I were thinking in two different ways, which may be important to make explicit for marsbars' benefit:

1. I was thinking in terms of the volumes required, at the specified dilutions, to get the specified number of rolls (16) out of the product (1l of Ilford DD-X) using the specified dilution (1+4). To get 16 or more rolls, you need a tank that uses 312.5ml or less of solution. This ignores what I believe MattKing was thinking about....
2. MattKing was thinking in terms of the required capacity of the developer to completely develop a roll of film. If the claim of a 16-roll capacity is based on this, then you'd need to use at least 312.5ml of solution to be sure of complete development.

I don't know in which way Ilford means its "16-roll" claim. My assumption (perhaps a mistaken one) is that products marketed to hobbyists would use meaning #1; after all, the manufacturer doesn't know how big any individual's tank is, and so would create recommended dilutions that would work well even with small-volume tanks and number-of-rolls claims that are reasonable given typical tank capacities. It'd certainly be disastrous to the product's reputation if people tried to develop rolls in smallish (say, ~250ml stainless-steel) tanks using the recommended dilution and encountered failures.

I'm not very familiar with Ilford DD-X, but Ilford does have loads of information on their Web site. You might be able to find a document there that clarifies this matter.

Edit: I wrote the above while MattKing was writing his latest reply; I didn't see it until after I posted mine!

srs5694:

I'm not sure about Ilford, but I expect they do this in the same way as Kodak - capacity claims are based on the effective developing capacity of the stock solution prior to any dilution, rather than the volume of diluted chemistry.

The clue to this is that they (Kodak) also say that one 35mm - 36 exp roll is equivalent to one 120 roll which is equivalent to one 8x10 sheet - all of which would involve wildly varying amounts of working strength chemistry, depending on the developing method.

I'd be very surprised if the instructions respecting capacity that are packaged with DDX would be directed just to hobbyists. I would expect that they would be intended to serve the needs of MF and LF photographers too.

I grant you though, that my take on this matter is based on assumptions, although I am confident that this is the way it works with the Kodak materials I've been using for a long time.

marsbars:

The info to be gained from this is (if I'm right in my assumption about Ilford) is that the capacity figures quoted by the manufacturer are related only to chemical "capabilities" of the stock chemistry and not to the volume of diluted working solution used. In contrast, the recommended volumes on the tanks are just how much developer, stop or fixer you need to put into the tank to cover the films sufficiently.

As I said earlier, I use Kodak's HC110. There is a huge variety of dilutions used for that developer (I favour 1:63). Many of the users of HC110 use it as a one-shot and measure out relatively tiny amounts of the stock (e.g. 5 ml) for each roll they develop. When you think of people working that way, you can see that capacity information from the manufacturer only makes sense if it refers to the capability (not volume) of original undiluted stock solutions, as they come from the manufacturer.

Sorry if we have ended up confusing you, rather than helping

Matt

 

[marsbars]

I think that I am starting to grasp the ideas here. It isn't that I am trying to be a cheap skate but I was confused to the process and wouldn't be able to stand using 4 times the developer solution than needed to process a certain quantity of film.

 

[dancqu]

...the capacity recommendations from the manufacturers are
sufficiently conservative as to leave a little wiggle room, Matt

More than a little. ACU-1 is good for at least 50% more and
Rodinal can be an easy 100% more. Of course the increased
dilutions call for an increase in development time. I'd gamble
24 rolls from that liter of DD-X. Make that 25 rolls. Each one
will need 40ml of the concentrate. If Ok go for 32. Dan