Can I mix only part of a bag of D76?

InsuredDisaster · Feb 1, 2012

EDIT: AW CRAP! I see this has been answered before. First post and I just post an overasked question. My bad. Mods, feel free to delete this turd.

I'm a cheap bastard and have 100+ rolls of BW film sitting in a big box so I figured rather than buy 1 gallong bags of D76, I'd buy a 10 gallon bag. But then it arrived (actually Legacy Pro L76) and suddenly I've got cold feet. My plan was to just use 10% of the bag at a time, but my concern is that I'll pour in an unbalanced mix of powered chemicals. I'm assuming that there are actually a number of different powered chemicals in the bag, and instead of having a mix of 50-50 (say if there were only 2 chemicals) I'll end up with a mix of 30-70 or something awful like that and end up with a useless batch off D76.

So, can I mix just 10% of the bag at a time or would that ensure a disaster?

Thanks.

markbarendt · Feb 1, 2012

Not reliably, doesn't mix/isn't mixed in a uniform manner as a powder so you don't really know what you will get if you mix a partial batch.

keithwms · Feb 1, 2012

I mix partial batches all the time, it works well without any issues.

EASmithV · Feb 1, 2012

You're not supposed to, but i've done it before without any ill effects.

tkamiya · Feb 1, 2012

I think your reel will unroll and film tank will explode if you do that.

Thomas Bertilsson · Feb 1, 2012

tkamiya said:
I think your reel will unroll and film tank will explode if you do that.

Definitely explode. Yes...

fotch · Feb 2, 2012

Hello InsuredDisaster and welcome to APUG. Interesting name, I won't ask you how to came to choose that. Anyway, rather than risk having a problem, mix up all of it and then use as much of it as you can. It does keep awhile if in bottles filled to the brim.

Perhap if there are other photographers near you, you could share it with them.

RalphLambrecht · Feb 2, 2012

InsuredDisaster said:
EDIT: AW CRAP! I see this has been answered before. First post and I just post an overasked question. My bad. Mods, feel free to delete this turd.

I'm a cheap bastard and have 100+ rolls of BW film sitting in a big box so I figured rather than buy 1 gallong bags of D76, I'd buy a 10 gallon bag. But then it arrived (actually Legacy Pro L76) and suddenly I've got cold feet. My plan was to just use 10% of the bag at a time, but my concern is that I'll pour in an unbalanced mix of powered chemicals. I'm assuming that there are actually a number of different powered chemicals in the bag, and instead of having a mix of 50-50 (say if there were only 2 chemicals) I'll end up with a mix of 30-70 or something awful like that and end up with a useless batch off D76.

So, can I mix just 10% of the bag at a time or would that ensure a disaster?

Thanks.

yes, you can, but you may get sa partly developed film

Steve Smith · Feb 2, 2012

The people who advise not to do this are being guided by questionable reasoning such as logic and common sense.

If you think you can give the dry ingredients a good mix before you divide it up, there should be no problems.

Steve.

Rick A · Feb 2, 2012

Not questionable reasoning, just a cautious aprehension to seperating dry chems that most likely are not a true homogenous blend. But, what the heck, go for it. The worst that can happen is not all rolls will develope the same. The best that can happen is you are happy with the results.

Steve Smith · Feb 2, 2012

Rick A said:
Not questionable reasoning, just a cautious aprehension

You misread my post. I agree with you really!

I was saying that logic and common sense would suggest that it wasn't a good idea. However, it's sometimes a good idea to do things which are not a good idea (?) as if we don't, we won't learn or discover new things.

Steve.

RalphLambrecht · Feb 2, 2012

Steve Smith said:
You misread my post. I agree with you really!

I was saying that logic and common sense would suggest that it wasn't a good idea. However, it's sometimes a good idea to do things which are not a good idea (?) as if we don't, we won't learn or discover new things.

Steve.

serendepity is rarer than one thinks

keithwms · Feb 2, 2012

RalphLambrecht said:
serendepity is rarer than one thinks

But it is also very valuable.

~~~

I agree with Steve; if I hadn't simply done my own experiments, I wouldn't have discovered that what some people were saying was complete parroted nonsense. Not just in this case but in many others cases where somebody said you can't, you shouldn't....

Notice how some people here are saying they did it and it worked; others are saying maybe you will get this or that.... implying that they haven't actually done it.

I've been doing partial batches of all photographic chems for years. No issues whatsoever. Am I just lucky? Undiscerning? Assisted by the gods of good fortune...? Maybe karma will come up and bite me in the ass one day and one whole roll of film will be slightly misdeveloped, ouch.

faustotesta · Feb 2, 2012

Once i put this question to the shop where i buy chemicals (they're very competent) she told me not do that. In her advice all the powder should be mixed at the same time. In any case i wouldn't do it. In case the partially mixed solution doesn't work properly your roll is lost forever. Consider that the mixed solution has a reasonable expiry time range (if i'm not wrong it's about 6 months when properly stored). Buona fortuna

Thomas Bertilsson · Feb 2, 2012

I have an idea for you.

Purchase one 1 liter packet and mix that up. Then take 10% of the powder you bought for the 10 liter bag, and mix another liter. Mix the two together for a 2 liter batch, which you keep to use. When you are down to 1 liter, you mix another 10% and add it to the existing liter, and so on.

This minimizes the impact of a possible slight difference there might be from one portion of your large bag to the next.

Be very careful to store the remaining D76 powder in a container with as little air in it as possible, and without moisture getting to it.

InsuredDisaster said:
EDIT: AW CRAP! I see this has been answered before. First post and I just post an overasked question. My bad. Mods, feel free to delete this turd.

I'm a cheap bastard and have 100+ rolls of BW film sitting in a big box so I figured rather than buy 1 gallong bags of D76, I'd buy a 10 gallon bag. But then it arrived (actually Legacy Pro L76) and suddenly I've got cold feet. My plan was to just use 10% of the bag at a time, but my concern is that I'll pour in an unbalanced mix of powered chemicals. I'm assuming that there are actually a number of different powered chemicals in the bag, and instead of having a mix of 50-50 (say if there were only 2 chemicals) I'll end up with a mix of 30-70 or something awful like that and end up with a useless batch off D76.

So, can I mix just 10% of the bag at a time or would that ensure a disaster?

Thanks.

keithwms · Feb 2, 2012

Take the larger bag, mix it thoroughly, pinch it off half way.. no air will reach the unused portion. Aha! Tie it off, and that half bag is now as virgin and untouched by the foul elements as before; if any air is in there, it was the exasperated last gasp of a Kodaker in the factory...

If I were a salesperson I would probably also suggest buying a smaller bag rather than dividing: you pay more for the same amount.

Leigh B · Feb 2, 2012

NO. Absolutely not.

The constituent ingredients do not disperse uniformly throughout the volume,
so a portion of that volume will not have the right amount of each ingredient.

- Leigh

keithwms · Feb 2, 2012

If you simply shake it well ahead of time and divide as I described there will be no issues. I have been doing it for years with absolutely no ill effects. So... either I am just a lucky guy or this salesman's theory really is as much bunk as it sounds like.

Leigh B · Feb 2, 2012

keithwms said:
I have been doing it for years with absolutely no ill effects. So... either I am just a lucky guy or this salesman's theory really is as much bunk as it sounds like.

No, not lucky. I suspect your standards of quality are not up to those of the manufacturer.

Shaking WILL NOT evenly disperse powdered chemicals in a container. I don't care how hard you shake it or for now long.

That's utter nonsense.

- Leigh

paladin1420 · Feb 2, 2012

I generally make a gallon of D-76 at once, but I store it in multiple half gallon or smaller bottles, filled to the very top. I have had stock solution stored like this perfectly usable after a year or more. If the year old D-76 is in any way less worthy than the brand new stuff, I have not detected it. Partially filled containers get yellow within a month or so.

keithwms · Feb 2, 2012

LOL I guess I'll just have to keep enjoying my nonsense then Leigh. The thing is, you probably never even tried it. If you had you wouldn't disagree with me, guaranteed.

Leigh B · Feb 2, 2012

Yes, I have tried it, with chemical analysis.

It failed, which is why I don't do it.

Amazing what science tells you that opinion hides.

- Leigh

Roger Cole · Feb 2, 2012

OTOH, others have tried it with film and got results they were happy with. It's amazing what application will tell you that analysis may not.

I think the real lesson here is that most photo chemistry is pretty non-critical. Witness all the people who mix D23 using teaspoons and tablespoons to measure the sulphite and metol. It doesn't matter if they mix perfectly, or even particularly well; all that matters is that they mix well enough for results and repeatability that the user is happy with.

So far, every single person who has posted about trying this with real film has reported good results. Has ANYONE here actually tried this, with film, and been unhappy with the results and consistency? Not analyzed the powder, not theorized, not worked it out mathematically, but simply mixed the powder as well as possible, mixed a partial batch, developed film with it, and compared the results to film developed by mixing an entire package?

Personally it's cheap enough I'd rather just mix the whole thing and toss after a reasonable time, but not everyone wants to do that, or can afford to toss half a gallon of D76 worth $3 every six months. (Yes, that's some sarcasm, but I'm also serious about the fact that so far, every single user who has posted about trying this with film has been happy with the results.)

keithwms · Feb 2, 2012

What did you do Leigh, leave one side open for a day? Must have. I'd love to hear about your scientific method. My result is clear that it works well. P.S. don't presume to lecture me on science, it's what I get paid handsomely to do.

litody · Feb 2, 2012

So how does baking a cake work then?

Can I mix only part of a bag of D76?

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