Obsidian Aqua, catechol staining developer

[Regular Rod]

They dissolve in the distilled water at room temperature (say 20 deg. C) reasonably easily with stirring. You could speed the process by warming it up a little bit. Sodium Metabisulphite in first, dissolve all, then Catechol, dissolve all is the correct order.

RR

[Tony Lakin]

Many thanks, much appreciated

[Tony Lakin]

Hi
I wish to try Obsidian Aqua 1ml to 1 litre for Tech Pan, do I need to halve the sodium carbonate, ie 2.5 grams to 1 litre instead of the 5 grams required at 1 to 500 dilution?

[Regular Rod]

Hi
I wish to try Obsidian Aqua 1ml to 1 litre for Tech Pan, do I need to halve the sodium carbonate, ie 2.5 grams to 1 litre instead of the 5 grams required at 1 to 500 dilution?

Yes. Put in half the amount of solution B as well. So...

Solution A 1ml into say 500ml of water then add 6.25ml of solution B then add water to make up to 1litre.

RR

[steveo]

Can I ask a newbie question. If I bought a 2kg bag of Anhydrous Sodium Carbonate how much solution B would this make and how much of it would I add to the working solution? Also the working solution looks something like 1ml of A to ??ml of b topped off with water to make 500ml?

Edit: Found an earlier post by Regular Rod which suggests 1kg of the Carbonate to make 5l then using it 1:12.5 topped up to 500ml have I read this correctly?

[Taija71A]

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Please read:

http://hypercatacutancedeveloper.blo...dian-aqua.html

The answers to your questions are clearly explained above. Thank-you!
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Personally, I would start by making something like a 20% Sodium Carbonate (200g/liter) Stock Solution.
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Regards,

-Tim.
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[steveo]

Cheers Tim, that was the first one I stumbled across but I'm still a little confused by the second solution. Do you make up a large supply of very weak B instead of a stronger B?

[Taija71A]

... Do you make up a large supply of very weak B instead of a stronger B?

The Sodium Carbonate Stock (200g/liter) Solution (*That I suggest you make) ... Is your 'Stronger' B.

You of course, are 'free to make up' your Sodium Carbonate Stock Solution at a 'weaker' Dilution... But it won't keep as well.
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Cheers!
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[steveo]

Right, missed that sorry.
So you have 1ml A + 100ml B + 400ml water?

[Taija71A]

... So you have 1ml A + 100ml B + 400ml water?

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No.
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As a 'Starting Point'... Your 'Working' Developer needs to contain approx. 5g of Sodium Carbonate per/L.

You just added 20g of Sodium Carbonate to your 500ml of Working Developer.
(*100ml/1000ml x 200g/liter) = 20g.
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Please get back with the correct amount of 'B' Stock Solution to add -- Okay?
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Thank-you!

-Tim.
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