Quick Question (D76 1:1)

[bvy]

I've read that if I'm going to dilute D76, to dilute it just before developing -- i.e. don't keep or store diluted developer. I use it 1:1. What about bringing it to temperature? Should I bring the stock solution and water to temperature separately then mix the working solution, or can I mix the working solution then bring it to temperature? Or does it matter?

And just as a matter of curiousity, roughly how long does diluted developer keep? Thanks.

[cliveh]

Allow me - The method I use is one I picked up some years ago and assuming
You’re using tap water as part of your developing solution and not distilled or
Deionized water, this method is fairly easy.

To make a 1:1developing solution for one 35mm film, you will need 150ml of water
mixed with 150ml of developer = 300ml (I know it says 290ml on the tank, but 300ml
and its division by ½ to 150ml is easier to remember). This mixture of developer and
water should ideally be at a temperature of 68F/20C.

Pour 150ml of developer into a measuring jug and measure its temperature. If it is
under or over 68F/20C, make a separate jug of water to compensate for the difference. Example – if the developer temperature is 18C, make the water to 22C, before adding 150ml of water to the developer. To get the water at the required temperature, put a thermometer in the empty jug and add hot and cold, either from two separate taps or a mixer taps. Don’t worry about the quantity as you can let the excess flow over the edge, just concentrate on getting the temperature differential you require. Then pour out the excess to leave 150ml and add to the developer in the separate jug.

Thus, you have 300ml of developing solution at 68F/20C

Discard after use.

[John Austin]

I would suggest you mix the 1:1 just before use as the additional water will carry oxygen which will speed up the decay of the metol and hydroquinonne - However, it will be OK for a reasonable time while you get the temp' right

An easy way to get the temperature almost right is to measure the temp' of the stock sol'n and adjust the water to the same number of degrees the other side of 20 deg' C to bring the mix back to 20 deg'

You will have plenty of time to make minor adjustments with the aid of a water bath, or use the sliding scale temperature chart thingie from Ilford

[Worker 11811]

I put the stock developer into a glass measuring beaker, stick in a thermometer and pour in hot (~100º F.) water a little at a time, stir and repeat until the temperature is what I want it to be. (Usually 68º F / 20º C) If your hot water is hot enough, you should easily get your mixture up to temperature without going over the target volume.

Next, I get my faucet running at the temperature I want. (68/20) I let it run, slowly, into a plastic tub so that it overflows. Just a trickle is all you need. This does two things: First, it buffers my water against sudden temperature fluctuation. A small ±1º change will easily be absorbed by the volume of water in the tub. Second, it gives me a reservoir of pre-tempered water to dip from whenever I need it.

Now, I have a partial beaker of developer/water at the right temperature and a reservoir of tempered water at my disposal. All I have to do is dip out the right amount of water to top up my beaker of developer to the volume I want and stir.

I'm ready to develop and no math is involved.

[ParkerSmithPhoto]

I mix mine up 1:1, just a bit below the total volume. Pop it into the microwave for a few seconds on low power, and then check the temp again. You'll be surprised how easy you get the hang of this. If you go over just a touch, add an ice cube to bring it back down. Super easy.

[bvy]

Thank you all. I should have mentioned that I use distilled water, so developer and water are at the same room temperature when I begin. My idea was to prepare the solution in a pet bottle (easy to squeeze out the excess air), and drop it into a water bath to bring it to temperature. Will it keep for however long that takes? How long will it keep for that matter?

It sounds like switching to tap water might be easier.

[Blighty]

or can I mix the working solution then bring it to temperature? Or does it matter?

And just as a matter of curiousity, roughly how long does diluted developer keep? Thanks.

I dilute stock first and bring it up/down to temperature as required. Usually, I'm ready to go well within 30 minutes of dilution and on a couple of occasions it's been (a lot) longer than that. But, regardless of how long a delay between dilution and use, I can't say I've ever noticed any difference in neg quality whatsoever.

[Smudger]

If you put your developer into a stainless steel beaker,and dip it into a container of hot water,while stirring with a thermometer,you can bring it to temperature within a few seconds. The rapid heat transfer does the trick.

[bvy]

If you put your developer into a stainless steel beaker,and dip it into a container of hot water,while stirring with a thermometer,you can bring it to temperature within a few seconds. The rapid heat transfer does the trick.

Interesting idea. I don't have a beaker but I do have a spare stainless steel developing tank (I use Paterson tanks for developing). Seems like that might work just as well.

[Worker 11811]

That's one of my backup plans when my cold water temperature goes above 68º in the summer. Hot or cold water bath to bring the solution to the temperature needed. I usually use plastic margarine tubs that would have ordinarily been tossed into the recycle bin. Just make sure you clean them really well, first. (The dishwasher usually does the trick.)

Another option you can use when your solutions are warm is to use an ice cube or two. Drop one into the solution and stir while it melts and cools the solution. Repeat one or two cubes at a time until you have the solution at the right temperature.

BTW: Not picking on you but you don't absolutely need to use distilled water for your working solutions, provided your tap water is not crazy out of whack. Most commercially produced products have chemicals in them to counteract a certain amount of hardness or other problems so that the developer will work normally. It saves you a fair amount of work hauling jugs of distilled water home from the store unless you have a distiller at home.
Yes, you should mix your stock solutions with distilled water but, when mixing working solutions from stock, it's not necessary.
But, then, again, if you have bad water, keep doing what you've been doing.