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Edwal TG7????

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Paul Verizzo

Member
Joined
Jan 20, 2008
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1,648
Location
Round Rock, TX
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35mm
I was at the library today and was perusing a book that showed some film and developer curves. Holy moly, there was a developer I never heard of and it had the nicest shouldered highlights on TMX I'd ever seen. Edwal TG7. I cerainly knew of FG7, but not this.

I came home all ready to either research TG7 and/or buy some.........

Well, there is almost nothing on the internets about it, and even B&H doesn't carry it. No MSDS out there, just a few comments in the other forum and none in this one. What I could gather is that it was designed for T grain films - hmmm, Tg7 - and that several posters really liked it with T-Max and Delta films.

Does anyone hear know anything about it? Chemistry? How to use? If there is a secret stash anywhere?

Thanks!
 
My Recolection of Edwals TG-7

I used Edwals TG-7 years ago with T-Max films. I thought it was a godsend, especially when used with T-Max 3200 and a dose of sodium sulfite. It yielded negatives that had minimal grain and tamed the highlights that were difficult to deal with when using T-Max developer. The downside was short shelf life for once opened, and that it was not universally available. I learned about the developer from a favorable article in the old Camera and Darkroom magazine. Falcon Safety Products was the original distributor, and when Falcon sold the photochemical business to BKA, the product faded away. Its formula, I believe, remains secret.
 
O Fernandez said:
I used Edwals TG-7 years ago with T-Max films. I thought it was a godsend, especially when used with T-Max 3200 and a dose of sodium sulfite. It yielded negatives that had minimal grain and tamed the highlights that were difficult to deal with when using T-Max developer. The downside was short shelf life for once opened, and that it was not universally available. I learned about the developer from a favorable article in the old Camera and Darkroom magazine. Falcon Safety Products was the original distributor, and when Falcon sold the photochemical business to BKA, the product faded away. Its formula, I believe, remains secret.
Click to expand...

Thanks for all that info.

I did find some sites that contained a few bits. Like, TMX is developed 10.5 minutes with a 1:7 dilution. There was one forum entry that said he found that "too hot."

I'm not exactly a neophyte at developer formulations and characteristics. Yet, I am puzzled as to what the composition might have been. Since it converts a native straight highlight line to a nice curve, it must be either wearing out the developer in the highlights or the developer by-products trigger some kind of limiter.

Is it just a variant of good ole Beutler?

I want some!
 
Paul Verizzo said:
Thanks for all that info.

I did find some sites that contained a few bits. Like, TMX is developed 10.5 minutes with a 1:7 dilution. There was one forum entry that said he found that "too hot."

I'm not exactly a neophyte at developer formulations and characteristics. Yet, I am puzzled as to what the composition might have been. Since it converts a native straight highlight line to a nice curve, it must be either wearing out the developer in the highlights or the developer by-products trigger some kind of limiter.

Is it just a variant of good ole Beutler?

I want some!
Click to expand...

TMax development result descriptions sound somewhat like those produced by Windisch Pyrocatechin or perhaps Crawley's FX-1 (or, of course, Pyrocat).
 
Paul Verizzo said:
Wouldn't the pyro ones have staining? I know next to nothing about pyro or catchecol.
Click to expand...

Pyrogallol, pyrocatechol and Hydroquinone are all capable of producing image stain in proportion to the amount of exposure. Sodium sulfite added in sufficient quantity to the developer can prevent stain from forming.
 
There is also Pextral's Pyrocatechol based Two-bath staining developer.

Staining developers can be very effective at clamping highlights.

(there was a url link here which no longer exists)
 
Back on track, guys! Thanks for the thoughts, but my pondering was specifically TG-7 and how Edwal accomplished that S curve with a single bath developer in 7-11 minutes and no mention anywhere of staining. Sounds magical. Or at least, very clever.
 
Paul Verizzo said:
Back on track, guys! Thanks for the thoughts, but my pondering was specifically TG-7 and how Edwal accomplished that S curve with a single bath developer in 7-11 minutes and no mention anywhere of staining. Sounds magical. Or at least, very clever.
Click to expand...

If stain played a role, you can tell by bleaching a developed sample and/or by performing transmission densitometry on a developed sample that has been exposed to a 21 step Stouffer step wedge (or equivalent).
 
Tom Hoskinson said:
If stain played a role, you can tell by bleaching a developed sample and/or by performing transmission densitometry on a developed sample that has been exposed to a 21 step Stouffer step wedge (or equivalent).
Click to expand...
Here are my transmission densitometry results of a staining development example of Kodak TMAX 400 (TMY) developed in Pyrocat.

(there was a url link here which no longer exists)

The visual channel results show the silver image density and the blue channel results show the stain image density.
 
Going back to TG-7 for a moment, I used to use it exclusively with my TMax films. It is sadly no longer available. It would be nice if someone would publish the formula for it so it could be resurrected. It was so much nicer than any other T-grain developer available at the time. I didn't have a problem with exhaustion because I was going through so much film at the time that it never went bad before I kicked the bottle.
 
Tom Hoskinson said:
Here are my transmission densitometry results of a staining development example of Kodak TMAX 400 (TMY) developed in Pyrocat.

(there was a url link here which no longer exists)

The visual channel results show the silver image density and the blue channel results show the stain image density.
Click to expand...

Thanks for the help, but I'm not a subscriber.....

What kind of curve does it have?
 
TheFlyingCamera said:
Going back to TG-7 for a moment, I used to use it exclusively with my TMax films. It is sadly no longer available. It would be nice if someone would publish the formula for it so it could be resurrected. It was so much nicer than any other T-grain developer available at the time. I didn't have a problem with exhaustion because I was going through so much film at the time that it never went bad before I kicked the bottle.
Click to expand...

Do you still have any information TG7? Printed matter, whatever.

I'm beginning to think that it may just be a generic low developing agent quantity in a high alkalinity carrier. Not unlike Rodinal?
 
Paul Verizzo said:
Thanks for the help, but I'm not a subscriber.....

What kind of curve does it have?
Click to expand...

Paul, I will send the Excel spreadsheet (data plus curve) to your website email address.

The Silver Image density curve versus Log Exposure has a long linear portion that starts rolling over as the exposure increases.

The Stain Image density curve versus Log Exposure also has a long linear portion that starts rolling over as the exposure increases:

When the Silver Image density curve reaches a density of 1.0, the Stain Image density curve is at 1.12. Thus, the two curves diverge.

When the Silver Image density curve reaches a density of 1.12, the Stain Image density curve is at 1.27.

When the Silver Image density curve reaches a density of 1.49, the Stain Image density curve is at 1.75.

Hope this helps you visualize what is going on.
 
Thanks for the H&D curves, Tom. However, I don't see any type of shouldering, er, developing. The several I saw in that book weree distinct, virtually like XPx films.

I was amazed and sure would like to duplicate that type of curve.
 
Paul Verizzo said:
Thanks for the H&D curves, Tom. However, I don't see any type of shouldering, er, developing. The several I saw in that book weree distinct, virtually like XPx films.

I was amazed and sure would like to duplicate that type of curve.
Click to expand...
Paul, where on the D LogE curve does the "shoulder" you are looking for start? What is the maximum density level reached?
 
Paul Verizzo said:
I was at the library today and was perusing a book that showed some film and developer curves. Holy moly, there was a developer I never heard of and it had the nicest shouldered highlights on TMX I'd ever seen. Edwal TG7. I cerainly knew of FG7, but not this.

I came home all ready to either research TG7 and/or buy some.........

Well, there is almost nothing on the internets about it, and even B&H doesn't carry it. No MSDS out there, just a few comments in the other forum and none in this one. What I could gather is that it was designed for T grain films - hmmm, Tg7 - and that several posters really liked it with T-Max and Delta films.

Does anyone hear know anything about it? Chemistry? How to use? If there is a secret stash anywhere?

Thanks!
Click to expand...

I found it at VISTEK in Canada, with 16 oz with shipping cost me $35.00 WWW.Vistek.ca.
 
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