Most economic way to develop C-41 at home?

gazefuzzy

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I've purchased two Arista C-41 kits from Freestyle to develop C-41 at home. The first kit I disposed of because I mixed them and let them sit around for over a week, then realized I hadn't been storing the chemicals in airtight containers and bought a new kit to be safe. I've gotten good results from a couple of rolls of developing with the new kit, but it has been mixed for over a week now, and after the third roll I attempted to develop last night the developer got dramatically darker in color (went from a light yellowy pink to dark gray suddenly). I realize the developer will darken in color due to the dissolving of the anti-halation layer, but would this much of a color change make the developer unusuable? My kit did not come with specifics on shelf life of the chemistry after it is mixed, and I tried calling Freestyle who couldn't give me a specific answer but advised that the developer probably would not last for more than a few weeks.

Maybe the most economical way for me to develop is to buy a powder kit, only mix up a bit at a time and reuse that bit only a few times and then throw it out? How do you all strategize your C-41 chemistry? I am trying to be able to process around 25 rolls per month but not spend more than $30 per month on chemistry.
 

MattKing

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You cannot reliably use portions of a powder mix - it is impossible to ensure that each portion is the same as each other, because it is impossible to ensure homogeneity.

That being said, it seems to me that the people using these kits are getting at least a month of use out of them - I'm sure some of them will chime in here.
 

Sirius Glass

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I buy the least expensive C-41 kits from FreeStyle [http://www.freestylephoto.biz/10123-Unicolor-Powder-C-41-Film-Negative-Processing-Kit-1-Liter] and when I have enough film, about 12 to 16 rolls, I develop film in a series of batches over several days. While I am saving up exposed film, I put the film in Zip-Lok plastic bags and store them in the refrigerator. I wait until the film has come to temperature before I remove the film from the plastic bags to load the reels.

Do not mix partial batches of dry chemicals, ever. While some post claims that it works, it is asking for problems because the powders are not uniformly mixed and settling occurs. Photo Engineer has warned against mixing partial packages. One can get away with mixing partial batches but sooner of later problems will occur.
 

MattKing

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wildbill said:
don't mix it all at once.
there are dozens of threads discussing these kits. Read up.
Click to expand...
I could be wrong, but I think Vinny may be referring to the kits that come in liquid form.

Those kits permit mixing up partial amounts.
 
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gazefuzzy

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MattKing said:
I could be wrong, but I think Vinny may be referring to the kits that come in liquid form.

Those kits permit mixing up partial amounts.
Click to expand...

That makes sense. I hadn't thought of the unreliability of using partial powder kits, thanks for everyone's help on this. If I were to mix up portions of a liquid kit though, that brings up the question of how long would the unused portion of the liquid kit last before mixing?
 

Sirius Glass

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MattKing said:
I could be wrong, but I think Vinny may be referring to the kits that come in liquid form.

Those kits permit mixing up partial amounts.
Click to expand...

I agree that mixing partial batches of liquid chemicals is an accepted normal procedure.
 

canvassy

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I use the same Unicolor / Tetenal kits that Sirius Glass linked to. I get about 20 rolls out of the 1 liter. I just switched to the 2 liter kit and I'm hoping to get 40 rolls out of it. They're the cheapest kits and it ends up being roughly $1 a roll for me to develop this way. In my experience the shelf life of the kits is easily 6 months+ once mixed.
 

Sirius Glass

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Thank you. I did not know that one could get six months out of mixed C-41 chemicals. I thought that two months was the maximum. Does any one have experience with more than two months?
 

railwayman3

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I leave some of my C-41 and E6 to the lab, particulary if I need the results quickly. If I've more time, I will accumulated, say, 12-20 films, set aside a "processing" day, and use a single small fresh kit to exhaustion. Perhaps a bit tedious, but saves setting-up and putting-away, and some decent music or radio on the MP3 player makes it quite relaxing.
 

RPC

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I always mix the developer all at once. Stored in glass bottles, filled to the top and tightly sealed, I have had Kodak developer last several years! Oxidation protection is the key. It hardly changed color and still gave great results. I don't know about other brands. You cannot get this kind of life from partially filled bottles.
 

bvy

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Sirius Glass said:
Thank you. I did not know that one could get six months out of mixed C-41 chemicals. I thought that two months was the maximum. Does any one have experience with more than two months?
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I use the Kodak Flexicolor 5 liter kit. I mix everything at once and store it in 600ml bottles filled to capacity. The surfer girl in my gallery was from a roll developed with 12 month old working solution.
 

Wayne

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Sirius Glass said:
Thank you. I did not know that one could get six months out of mixed C-41 chemicals. I thought that two months was the maximum. Does any one have experience with more than two months?
Click to expand...

IIRC David Lyga stores it in small full bottles and uses it up to a year. But I think he also may do some unconventional things like diluting it so I better not say too much.
 

Jim Taylor

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I use Kodak flexicolor chemistry - the "makes 20l" concentrates and mix it up 500ml at a time. I replenish at the rates given in the literature and store the mixed solutions in glass bottles with pet stoppers. I store unmixed concentrates in a cool place in the containers they are supplied in (my DR is in a basement, in the UK, so high temps never a problem!!) Same with Kodak e6 chemistry. I last bought a batch of all of this over 2 years ago and no problems so far... No blackening of any of the developer parts either (like you can get with RA4 concentrates).
 

mts

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Your most economical method is scratch-mixing. You will have to spend some time finding bulk chemical components and expect in today's market to spend several hundred dollars to do so. I have used this method for many years and find the negatives (stored in notebooks and in the house) are all still just fine. I wait for 6-8 rolls of 24 exposures to accumulate and then mix 1 liter of chemistry to process over a one to two week period. If you process 6 rolls once a week that will do what you wish. Note that it is only necessary to mix new developer. The stop bath, fixer, and bleach last a long time and are good for more rolls. Stop and fixer should be good for perhaps a month and bleach (re-halogenated) perhaps longer. Only mix these chemicals when they are close to exhaustion which you determine by noting the time it takes to bleach and fix. As times lengthen to double or less than the process time, then mix fresh and start over. Developer is lost after processing perhaps a dozen rolls or a month if not used. The rest of the chemistry stays stable for months if stored in air-tight bottles and not used. Stop and stabilizer is so easy to mix that I replace it more often. Using this method, your cost will be pretty much the expense of developer which should turn out to be a couple of bucks per liter. The bulk chemicals are stable for years. Mine are over ten years old and were bought in at least 1 Kg quantity.

I don't store chemistry in the fridge since it is hard to tell bleach and used developer from Guiness.
 

alanrockwood

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MattKing said:
You cannot reliably use portions of a powder mix - it is impossible to ensure that each portion is the same as each other, because it is impossible to ensure homogeneity.
Click to expand...

The problem of using portions of a powder mix reduces to the same problem as unbiased sampling of a powder mix. There is an extensive literature on this topic, and the bottom line is that it is possible to do a pretty good job of it. Given that photography is not quite a high-precision science, it should be possible to use portions of a powder mix and get reasonably good results.

Three well-known techniques are to use a spinning riffler (probably not practical for the home chemist), a riffle box (probably not practical for a home chemist) and the cone and quartering method (practical for the home chemist). Here is a quote from the wikipedia page on this last method:

"The technique involves pouring the sample so that it takes on a conical shape, and then flattening it out into a cake. The cake is then divided into quarters; the two quarters which sit opposite one another are discarded, while the other two are combined and constitute the reduced sample. The same process is continued until an appropriate sample size remains."

Obviously, for a home chemist one would not discard portions of the sample, but simply use the method to divide the original powder sample into smaller sized portions.

There are a also several other ways of dividing a powder sample into smaller samples while minimizing bias in the sampling. There are advantages and disadvantages to each, and none are perfect, but they are nevertheless useful.

Riffling techniques tend to produce the best results (depending somewhat on the properties of the mixture) whereas cone and quartering is simple and does not require special equipment.

By the way, adding to my original post, there is also another relatively simple sampling/subdividing method called the long pile method.
 
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Gerald C Koch

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When you consider the cost of home kits and all the associated bother the cheapest choice is to have a reliable processing company do the work. Believe me I have been down both paths.
 

mklw1954

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bvy said:
I get mine (5 liter kit) through Unique Photo in New Jersey.
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Can you say exactly what Flexicolor items you get from Unique (product codes, etc.) to do C41?

I use Unicolor powder kits but would like to try Flexicolor. I don't live too far from Unique and pick up Kodak RA4 Ektacolor chemicals for color print development from them.
 
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