Mixing Dektol

Carol · Oct 16, 2005

I have recently acquired a small tin of Dektol developer. According to the instructions I should mix it with water which is 52C. Is there an easy way to guess 52C or am I going to have to buy a new thermometer as mine only goes to about 40C? Sorry if this seems a bit basic, I'm having a senior moment.

Cheers
Carol

David A. Goldfarb · Oct 16, 2005

It's not that critical. It should be pretty warm, but not boiling, and if you mix it a day in advance, it can settle so everything is dissolved.

Carol · Oct 16, 2005

Thank you David. I wasn't game to give it a go without a bit of reassurance. Much appreciated.

PhotoJim · Oct 16, 2005

52 is pretty warm (but not burning hot) shower water temperature, if that helps. Run the water so that it's very warm but not excessively hot to your skin, and you should be close.

John Cook · Oct 16, 2005

Carol, here is the web address for two temperature converters:

http://www.fone.net/~thovezak/intern15.html

http://65.247.222.38/cgi-bin/fahr2cel?temptype=2&temperature=52&submit=Convert

As you can see, 52 C = 125.6 F.

My experience has been that if you are perhaps ten degrees below the ideal temperature, some ingredients fail to go into solution. On the other hand, ten degrees over can "fry" some of the other ingredients, leaving the fresh solution lightly brown-colored and partially exhausted.

This phenomenon is, of course, more critical with film developers like D-76.

fschifano · Oct 16, 2005

Hot tap water, at least in my house, is pretty close to what you need for mixing Dektol. However, I don't recommend using tap water from the hot water heater. Often, the water will pick up impurities like rust and these might be detrimental. Dektol is not terribly sensitive to this, but some film developers are, so be careful. I find it best to start with cold tap water and heat it on the stove.

Tom Hoskinson · Oct 16, 2005

D-76 and D-72 (Dektol) are not very different chemically. If you are mixing either one from scratch, add a pinch of sodium sulfite first, then dissolve the Metol (aka Elon).

If the mixing water is too hot, you may oxidize the developing agents.

D-76 (there was a url link here which no longer exists)

D-72 (Dektol) (there was a url link here which no longer exists)

rbarker · Oct 16, 2005

If you started mixing the Dektol at 7:00 this morning, Carol, you should still be stirring the stuff.

fhovie · Oct 17, 2005

Man - am I glad I don't use Dektol. Actually - many chemistries mix better if you add some sulfite the the water first. Of course that is pretty difficult if you are mixing from a kit. Man am I glad I make my own. My hot tap water is 125F. It is too hot to put your hand in. I have never seen overheated water based chemistries turn color. I have mixed similar chemistries in TEA at 225F and they have turned brown - and still worked perfectly. I am not sure that they loose any performance if they do change color. I use a one liter bottle when I mixed powders and fill the bottle 2/3 full of hot tap water - (also never had a problem with tap water) I add the chemicals (sulfite first) cap and shake violently. The shaken bottle mixes better and faster than stiring. When the last powder is mixed in, I top it off with cold water. This leaves me within 20F of where I need it to be. An hour of soaking the bottle in cold water has it tempered and ready for use.

Carol · Oct 17, 2005

Lol I never thought of putting it in a bottle and shaking it. I went out and bought a cheap plunger type paint stirrer today because that was suggested in the instructions and you know how us womenfolk love reading instructions.

I haven't mixed it yet because I'm waiting for some Selectol Soft and I expect that'll need mixing too. I always use demineralized water for mixing chemicals as our town supply is bore water and my rainwater is fortified with bird droppings and possum poo so it only goes on my potplants.

Thank you all for taking the time to reply.

Tom Hoskinson · Oct 17, 2005

Carol said:
...I haven't mixed it yet because I'm waiting for some Selectol Soft and I expect that'll need mixing too.

Here is the formula for Kodak D-52 (aka Kodak Selectol).

(there was a url link here which no longer exists)

You will notice that D-52 (Selectol) contains the same chemicals - different proportions - as D-72 (Dektol).

To get the equivalent of Kodak Selectol Soft, dilute the D-52 stock solution 1:3 with water.

If you want Soft AND Warm, add Potassium Bromide (up to 1.5 grams/liter) to the 1:3 dilution working developer.

Gerald Koch · Oct 17, 2005

Metol (Elon) is said to be difficultly soluble in sulfite solutions. However, Kodak has developed a way that D-72 and some other developers can be manufactured as a single packet dry mix. If you follow the instructions by using 125F water the mix will completely dissolve within 15 minutes. Avoid aerating the solution by too rapid stirring.

I once was mixing D-76 from scratch and while I added a pinch of sulfite then forgot to add the Metol until after the sodium sulfite had all been added. Heating the solution to 125F and using a magnetic stirrer enabled me to dissolve the Metol without much difficulty. I then added the remaining ingredients and everything was fine.

fschifano · Oct 17, 2005

Whatever you do, don't shake the bottle to dissolve the contents. That introduces a lot of air into the mix and oxygen is a developer's worst enemy. Stir it plenty if you must, and try not to stir too much air into the mix. If it doesn't all dissolve within 15 minutes or so, don't worry about it. bottle the stuff up and let it sit for a while. Most everything will go into solution overnight and a small bit of particulate material at the bottom won't matter.

fhovie · Oct 17, 2005

fschifano said:
Whatever you do, don't shake the bottle to dissolve the contents. That introduces a lot of air into the mix and oxygen is a developer's worst enemy. Stir it plenty if you must, and try not to stir too much air into the mix. If it doesn't all dissolve within 15 minutes or so, don't worry about it. bottle the stuff up and let it sit for a while. Most everything will go into solution overnight and a small bit of particulate material at the bottom won't matter.

I have never had any developer failures even out to a year doing this - The air comes out of the fluid by the time it cools and the mixture is mostly H2O - among other things there is a ton of deterioration waiting to happen the moment it gets mixed. I understand the idea but in practice it seems I get all the chemicals disolved easily this way.

craigclu · Oct 18, 2005

For this type of mixing, I use a 1 gallon glass thumb jug. I slowly roll it back and forth. It seems to not over-stir/agitate, avoiding driving air into the mix and the container makes a perfect decanting source when you bottle it off into smaller containers.

Gerald Koch · Oct 18, 2005

One of the best investments I ever made was a magnetic stirrer. It gently stirs the mixture without whipping in any air. Saves the old wrist too.

Gerald Koch · Oct 18, 2005

One of the best investments I ever made was a magnetic stirrer. It gently stirs the mixture without whipping in any air. Saves the old wrist too.

John Cook · Oct 18, 2005

Carol, I'm definitely with fschifano on this "shaking" issue.

I have been making my living with Dektol and D-76 since 1965. In that time, I have probably gone through more developer than some of these novices have drawn bath water.

It has been "common knowledge" for a century that oxygen ruins developer. Strong stirring or any kind of shaking introduces oxygen into the solution. The bubbles rise to the top, but the oxygen remains.

You will eventually figure these things out for yourself. Either the easy way from listening to old-timers or from the school of hard knocks.

Bighead · Oct 18, 2005

rbarker said:
If you started mixing the Dektol at 7:00 this morning, Carol, you should still be stirring the stuff.

ha ha.... My girlfriend, a schools photo lab assistant, uses a drill with a 3ft long mixer attachment to mix that crap... Its friggen hilarious....

John Cook · Oct 18, 2005

As we now begin to drift into the winter months here in the northern USA, powdered chemicals begin to (once again) make a lot of sense, even with the stirring.

Having to thaw plastic bottles of solid ice that was once developer, while checking for expansion splits, after a long ride in the back of unheated UPS trucks can be friggen hilarious as well...

Mixing Dektol

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