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  #21  
Old 28th February 2009, 01:49 PM
Ag-Bromide Ag-Bromide is offline
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Originally Posted by Mike O'Pray View Post

Equally in this case it may have failed on both counts and served only to puzzle or even annoy which was not my intention.


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I was not annoyed, but I was puzzled as to why Technidol was mentioned.
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  #22  
Old 28th February 2009, 04:27 PM
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Originally Posted by Ag-Bromide View Post
Yes and it`s very similar to Perceptol. The MSDS that I have for Microdol-X show the ingredients as Elon, Sodium Sulphite, Sodium Chloride and Diboron-Trioxide (anhydrous boric acid). This isn`t mentioned in the current MSDS. The grain might possibly be a bit finer with the Kodak developer.
I have a 5 litre size package in a tin can and a 1 litre size. I also have Perceptol, although my own personal favourite developer for general use is Kodak D-76.

http://www.kodak.com/eknec/PageQueri...q-locale=en_GB
That close similarity to Perceptol is I guess why its rare in the UK.
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  #23  
Old 14th March 2009, 03:52 PM
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agenoria2 agenoria2 is offline
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THis formula is D23 with added Sodium Chloride & has been known for many years.

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Originally Posted by Peter Hogan View Post
The one stop loss in speed when using Perceptol comes from the fact that metol is the sole developing agent. In most developers it would be mixed with Hydroquinone to make a super-additive developer, and maintain the speed. Nevertheless, it is a fine developer, and I have used it often. Just didn't like losing speed...
Quite incorrect, D23 gives no drop in film speed it's comparable to D76, as any Kodak handbook will tell you, and it is a Metol only developer. The drop in film speed is entirely due to the chloride.

Ilford published a paper about this in 1965, ID-11 can be turned into a Extra Fine Grain developer by adding 40 g/litre Ammonium Chloride and doubling the dev time and increasing exposure by 50%

Microdol-X has metabisulphite and boric acid as preservative to help stability in the powder form, although metabisulphite is used in D25 to turn a fine grain dev into an extra fine grain dev by reducing the alkalinity.

Ilford also use a very small amount of Metabisulphite in some of their powdered devs (for example Bromophen) along with the developing agents.

Mac
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  #24  
Old 18th June 2009, 06:10 PM
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Originally Posted by agenoria2 View Post
THis formula is D23 with added Sodium Chloride & has been known for many years.



Quite incorrect, D23 gives no drop in film speed it's comparable to D76, as any Kodak handbook will tell you, and it is a Metol only developer. The drop in film speed is entirely due to the chloride.

Ilford published a paper about this in 1965, ID-11 can be turned into a Extra Fine Grain developer by adding 40 g/litre Ammonium Chloride and doubling the dev time and increasing exposure by 50%

Microdol-X has metabisulphite and boric acid as preservative to help stability in the powder form, although metabisulphite is used in D25 to turn a fine grain dev into an extra fine grain dev by reducing the alkalinity.

Ilford also use a very small amount of Metabisulphite in some of their powdered devs (for example Bromophen) along with the developing agents.

Mac
There is a very long thread about this developer over on apug. The post by Bill Troop are quite revealing if you search for Microdol-X. I think I have sussed out the formula for the replenisher as well as the developer and discovered the anti-stain agent used from a patent, but I`m keeping it under my hat for the time being.
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  #25  
Old 19th June 2009, 08:45 PM
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Not being a chemist, what does the Sodium Chloride actually do other than reduce the effective film speed? The Perceptol 'look' is very different to thet with D23 - so how does is work?

Rob
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  #26  
Old 20th June 2009, 03:13 PM
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Quote:
Originally Posted by Rob Archer View Post
Not being a chemist, what does the Sodium Chloride actually do other than reduce the effective film speed? The Perceptol 'look' is very different to thet with D23 - so how does is work?

Rob
Hi Rob,
It might be easier to ask either Bill Troop or Ron Mowrey (Photo Engineer) for an in depth explanation if you don`t mind being blinded with science.
In the thread (on the other side) Bill mentions that Richard Henn who formulated D-23, D-25 and DK-25R replenisher, wanted to avoid using bisulphite in the Microdol formula because of the very long development times required.
Henn also found that the amount of Elon in D-23 was excessive for the newer thin emulsion films that were then becoming available, hence 5 grams per litre of stock. I`m not sure of how the chloride works to make the grain finer.

Provided the weight of sulphite and chloride in the replenisher is the same as in the developer, then an approximate formula for that would be:

REPLENISHER.

Metol = 6.3 grams
Sodium sulphite, anhydrous = 100 grams
Sodium chloride = 30 grams
Sodium carbonate, monohydrate = 8 grams
WTM 1 litre of stock.

In the commercial Kodak developers, there is a very complex method for packaging developers which are compounded into a single-powders, that involves the use of boric anhydride to protect them reacting with the other components until they`re mixed with water, but that`s another story which is better explained by Ron and others in the know.

Microdol-X is said to be Microdol with the addition of an anti-stain agent which helps to prevent dichroic fog.
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  #27  
Old 18th October 2009, 03:07 AM
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Thanks Pete, that recipe will save me hunting all over Singapore for Perceptol next week
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  #28  
Old 19th October 2009, 12:08 PM
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Originally Posted by Barry View Post
That's interesting Pete. Most of the rumours regarding the composition of Perceptol have suggested that it is D23 with 30g of Sodium Chloride. Well that's just about correct except the Sodium Tripolyphosphate. Anyone know what this does?

My understanding is that sodium triphospahte sequesters calcium and magnesium ions- in other words it acts as a water softener.

It also acts as a pH buffer.

This answer is perhaps not a lot of practical use, but it does close out Barry's question above.

Niall
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  #29  
Old 19th October 2009, 06:55 PM
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Originally Posted by Niall Bell View Post
My understanding is that sodium triphospahte sequesters calcium and magnesium ions- in other words it acts as a water softener.

It also acts as a pH buffer.

This answer is perhaps not a lot of practical use, but it does close out Barry's question above.

Niall
Indeed, thanks Niall.
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  #30  
Old 30th November 2010, 09:04 PM
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I have just come across this thread whilst having a look around and sat next to my ex chemist wife. What is Metol? Where would one buy these chemicals?

How much cheaper does it work out mixing your own?
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