Tuesday, April 17, 2012

Designing a developer part 3. Getting chemicals and mixing the developer.

Chemicals, where do we get them?

In order to mix this or another developer, we obviously need some chemicals.

We need the developing agents,  the sulfite, the alkali, the acid to adjust pH, the restainer and the chelating agent.

Many chemicals can be bought from specialists in photographic chemicals, but a lot can be found on e-bay.

Most photographic chemicals can be bought from Silverprint in the UK or Photographers' Formulary in the US. In addition to them, Fototechnik Suvatlar in Germany has a lot of chemicals in store.

Links to this companies at the bottom of this article.
BTW, Fototechnik Suvatlar is the only one that I have found that sells the Fotoplex-2 or Dequest 2010 in europe. He has the 60% solution in stock, not the 99% powder as I got.

Well, after buying a lot of white powder, and hopefully got it through the customs without being incorrectly arrested for importing drugs, we are ready to start mixing the developer.

Not quite! To mix this developer we need wery small amounts of some chemicals. We can't miss on this. Using twice the amount of specified, may result in a non working developer.
It's obvious that we need a precise scale.
If you haven't got one, buy one and don't continue until you have it in your hands.

They don't cost an arm or a leg, just a few dollars.

Try this search on e-bay:

e-bay search for 0-300g electronic scale

The first one:0-300g scale is good enough for our use.

Next you will need some small bottles. 100ml is good.
You will also need some methylated spirits or denaturated alcohol to dilute developing agents and restrainers in.

Start with mixing a 1% solution of phenidone in 100ml methylated spirits.
Dissolve 1g phenidone in 100ml methylated spirits. This is your 1% phenidone solution.
Label it as Phenidone 1%.

Mix a 1% solution of potassium iodide. Following the same procedure, dissolve 1g KI in 50ml methylated spirits and 50ml water. Label it as Potassium iodide, KI, 1%.

Mix a 1% solution of hydroquinone. Following the same procedure, dissolve 1g hydroquinone in 100ml methylated spirits.

Why do we mix it in alcohol?
Because it doesn't contain water to any degree, so there is almost no free oxygen to destroy our developing agents.

Why the water in the KI solution? because it's easier to dissolve that way, and it doesn't go bad anyway, so water here is ok.

At this moment we can start mixing the developer.

Mixing the developer.

Let's summarize what we have decided to use.

10g Sodium Sulfite
0.25g Hydroquinone
0.35g Phenidone
4g Borax
1g Boric Acid.
0.01g Potassium Iodide.
1g Fotoplex-2 AKA Etidronic acid

If your tap water is clean, without chemical additives and with a neutral pH, boil 1.5 liter of it and let it cool down to no more than 30c.

If your water is alkalic or contains large amounts of clorine or other additives, use distilled water.

Start with 700ml water in your 1L graduated beaker.
Add the 10 grams of Sodium Sulfite to the water and stir until it's completely dissolved.
Add the 4 grams of Borax decahydrate and stir until it's completely dissolved.
Add 1g Boric Acid and stir until it's completely dissolved.
Add 1 g Fotoplex-2 or Dequest 2010 if you have the powder version.
If you got the 60% solution from Suvatlar, use 1.67ml of it.
To measure small amounts like this, it's best to use a  small syringe. Use a 5ml or 10ml size.
Add 35ml of the 1% Phenidone solution.
Add 25ml of the 1% Hydroquinone solution.
Add 1ml of the 1% Potassium iodide solution.
Top up with water to 1000ml.

How did I come up with the number of milliliters for the different solutions?
Lets take the 1% KI solution. It contains 1 gram in 100ml.
Each ml contains 1/100 of the one gram, 0.01 gram.

Why not just use the scale to weigh out 0.01gram since it has 1/100 gram resolution?
Well, if the scale displays 0.01 gram, it may be 0.0051 gram or even 0.0149 gram. The scale will display the same. In addition to this we have something we call precision. It is possibly 1/100 gram plus minus one digit. Take that into concideration, and you may even have 0.0249 grams and the scale still displays
When you weigh out 1 gram, the error may still be the same, but instead of disrupting our precision completely, it is 2.5% at most.
When you take 1ml of the solution, you will get somewhere between 0.0098 gram and 0.0102 gram.
That's more than close enough.

Fill the 1000ml of developer in a glass bottle. It should store ok, but if you want to increase shelf life, fill some lighter gas in the bottle on top of the developer. This will displace any air so it won't oxidize our developer.

When it has cooled down to 20c it's ready to be tested.

Testing wil be delt with in the next posting.
I have to keep you on your toes you know. :-)

Where to buy chemicals:

Silverprint in the UK.

Photographer formulary in the US

Fototechnik Suvatlar, on the homepage for Moersch Photochemie in Germany
Click the link "Preisliste Rohchemie" for a PDF pricelist.

Keten Chemicals in Poland 


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