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  #1  
Old 4th November 2022, 10:43 PM
Nat Polton Nat Polton is offline
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Default PMK Safe ?

https://www.ebay.co.uk/itm/125446095...Bk9SR6jGz8yIYQ

This advert says that PMK Developer is safer than Pyro 510.
Is this true?
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Old 5th November 2022, 12:21 AM
Mike O'Pray Mike O'Pray is online now
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Nat I'd look at the ingredients in both and then decide My understanding is that PMK is based on pyrogallol as is 510 Pyro.

In liquid form which is what this seller sells then provided you wear gloves when dispensing it neither is particularly dangerous but greater care has to be taken when mixing pyrogallol powder to make either developer

So I think the short answer is that in liquid form both are equal in terms of danger/safety

I'd be curious where the seller gets his info?

It might be that he has read something that he is repeating or he might be just trying to persuade buyers that his product is safer to sell it

A lot of people say things that they have just "heard"

I keep on thinking of the song in "High Society" where Frank Sinatra sings: Have you heard it's in the stars, next July we collide with Mars! Well did you ever? What a swell party this is"

Mike

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Old 5th November 2022, 07:57 AM
John King John King is online now
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Default Unsafe?

When you say one chemical or mix of chemicals is unsafe, do you mean there is a risk of damage to the film or is one more poisonous than the other?
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Old 5th November 2022, 08:04 AM
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Bill Bill is offline
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When you read the advert he is saying that it is safer because it is less concentrated.
Ian Grant is probably the best informed man to comment on this.
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Old 5th November 2022, 08:50 AM
Lostlabours Lostlabours is offline
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Yes PMK is a lot safer than 510 Pyro as sold. When mixed and dilute there's little difference.

The issue is Pyrogallol, or for that matter Pyrocatchin, are slightly toxic, as is the TEA in 510 Pyro, but on their own that's not a problem.

If we start with PMK, Part A with the developing agents is acidic, contains Metabisulphite so the oxidising properties of the Pyrogallo is inhibited until diluted and Part B the alkali (Sodium Metaborate) is added, by which time all the chemistry is quite dilute.

However, with 510 Pyro the one part concentrate and the TEA component becomes highly alkali on contact with water unleashing the strongly oxidising properties of Pyrogallol, staining anything it can oxidise. A UK manufacturer is deliberately downplaying the toxicity of the concentrate, unlike The Photographers Formulary in the US.

When you get statements like this " Another quick note despite showing several warning diamonds on the banner image, 510-Pyro, while not 100% safe, is incredibly non-toxic, based on studies by the EPA and ECHA." you know there's something wrong. The EPA and ECHA have data on the component chemicals, but their properties change radically when mixed, and the EPA and ECHA have not looked at 510 Pyro.

There are also claims that it's far less toxic than Kodak Xtol which is patently untrue.

More importantly the so called reviews all show poor quality results using 510 Pyro. See Parallax Photographic images here. Both these reviews (and all others) show that 510 Pyro gives no or extremely poor shadow details.

Ian
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Old 6th November 2022, 10:07 PM
Stocky Stocky is offline
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If you're tempted by the convenience of 510-Pyro, as I was, I suggest a careful side-by-side comparison with Pyrocat-HD before you commit to important negatives. I'm sticking with Pyrocat-HD. The lack of shadow detail with 510-Pyro is a total deal breaker for me.

For those anguishing over toxicity of pyrogallol, it is poisonous certainly, but it is also found in smoked meat in small amounts and has been used in cosmetics and skin treatments in significant concentration until fairly recently (not that I'm recommending it). There is a huge toxicology report about it if you're interested. I could find the link if you want.
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Old 7th November 2022, 03:17 PM
Lostlabours Lostlabours is offline
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Quote:
Originally Posted by Stocky View Post
For those anguishing over toxicity of pyrogallol, it is poisonous certainly, but it is also found in smoked meat in small amounts and has been used in cosmetics and skin treatments in significant concentration until fairly recently (not that I'm recommending it). There is a huge toxicology report about it if you're interested. I could find the link if you want.
I have read the various reports, as well as the relevant EPA and ECHA data, in addition discussed Pyrogallol's toxicity with an organic chemist who's PhD was in this field.

What makes 510 Pyro different is the fact it's dissolved in TEA (as mentioned in my previous post above) and becomes a strong alkali on contact with water, as it;s also like a thick treacle it's very significantly more toxic and hazardous than any other Pyro developers.

Ian
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