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Old 19th February 2009, 03:31 PM
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Default Perceptol Formula

Would you be interested in the formula for 'Perceptol'? I got it from a bloke who worked in Ilford's Woodman Road, Brentwood factory when it was being closed and all the gear was being given away to photo colleges or thrown away and workers lost their jobs.
Sodium Tripolyphosphate 3.5 gms
Metol 5.0 gms
Sodium Sulphite anhyd.100.0 gms
Sodium Chloride 30.0 gms
water to 1 Litre
I suppose the Sodium Tripolyphosphate could be left out if SOFT or DISTILLED water is used.
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Old 19th February 2009, 08:05 PM
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Interesting. I never knew what the formula was, but in hindsight should have guessed. The sharpness comes from the metol, obviously - metol is known for it's sharpness. 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...
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Old 19th February 2009, 08:25 PM
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THe strange thing is that for almost all film speeds, Perceptol has dev time for EIs that are at least 1/3rd stop less or more usually one stop less. Then you get to D3200 where it lists time for box speed. OK I know that D3200's real speed is said to be about 1000-1250 but yet Perceptol allegedly "works at EI 3200.

How are these seemingly contradictory situations reconciled i.e. no times for slower films at box speed and yet a time for Ilford highest speed film at its highest speed?

Mike
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Old 19th February 2009, 08:40 PM
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are you saying those speeds are obtained or that they are claimed.
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Old 19th February 2009, 10:03 PM
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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?
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Old 22nd February 2009, 01:04 PM
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Quote:
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?

Most big chemical producers, besides using the normal developing agents, will add various chemicals to try to overcome the huge differences in tap water around the world. Tripolyphosphate is one of those chemicals. You can safely leave it out if you're mixing your own.
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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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Old 30th November 2010, 09:22 PM
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Quote:
Originally Posted by cowasaki View Post
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?
To give a very unscientific answer, metol is a compound that is a very good developer when mixed with other stuff. It's available from several suppliers with links here. I use Silverprint, whose customer service is excellent. As far as cost goes, I reckon that litre for litre, home made chemicals are around 2/3 cheaper than ready-made.

The main benefit (for me, anyway) of home-brews is that, as you learn more about the different properties of the chemicals it is possible to modify the recipes to get just the results I want. It just takes a little care, and a close eye to healt and safety issues (although most photographic chemicals are relatively benign if you follow the rules). Try getting hold of 'The Darkroom Cookbook', by Anchell & Troop - you'll find plenty of mention of it on FADU.

Rob
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Old 30th November 2010, 09:29 PM
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Quote:
Originally Posted by Rob Archer View Post
To give a very unscientific answer, metol is a compound that is a very good developer when mixed with other stuff. It's available from several suppliers with links here. I use Silverprint, whose customer service is excellent. As far as cost goes, I reckon that litre for litre, home made chemicals are around 2/3 cheaper than ready-made.

The main benefit (for me, anyway) of home-brews is that, as you learn more about the different properties of the chemicals it is possible to modify the recipes to get just the results I want. It just takes a little care, and a close eye to healt and safety issues (although most photographic chemicals are relatively benign if you follow the rules). Try getting hold of 'The Darkroom Cookbook', by Anchell & Troop - you'll find plenty of mention of it on FADU.

Rob
Thank you, that was a nice quick answer!

I am currently typing this with virtually no skin on either thumb and 4 other digits with leathery skin thimbles waiting to fall off too! This was due to using Ilford ID-11 + Ilfostop + Ilfofix without gloves and just the chemicals that came out of my not very liquid proof and since replaced film dev tank whilst agitating it! With a chemist as my other half I think it might be worth having a mess with the contents of that book. Being able to mix chemicals in the amounts I want from dry might work out better anyway.
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Old 19th October 2009, 12:08 PM
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Quote:
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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