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Photo Engineer
01-25-2012, 10:54 AM
Borates are difficult to dissolve and are not environmentally friendly to citrus crops and some other plants. That is one good reason to avoid them. TEA is a bit better and allows a concentrate to be made more easily with K2SO3.

Dimezone S is more stable and in some cases gives superior development than the other compounds in the Dimezone family.

PE

Alan Johnson
01-25-2012, 11:40 AM
www.mistralni.co.uk will apparently ship TEA in Europe and Scandinavia but the shipping cost makes it expensive.

albada
01-26-2012, 03:26 PM
I figured out a simple way to use a light-meter as a densitometer.

First, cut out a piece of pasteboard to use as a shield. Pasteboard is the thin cardboard used to hang small products on pegboard racks in stores. The product is typically shrink-wrapped onto the pasteboard. You see it everywhere. Pasteboard is thick enough to block all light. Drill or punch a 2 mm hole into the pasteboard. Or cut a triangular or square hole with an Xacto knife. You now have a thick card with a hole in it.

To measure density, place the hole over the desired part of the negative on the light-table, place the meter's cell over the hole, and measure. Subtract this measurement (in EV) from a base+fog measurement taken the same way, and you'll get density above base+fog in EV. Multiply that by .301 to convert to optical density.

Comparing my test-dev neg from my XTOL neg, a dense area in both had a difference of 0.06 (optical density). So I got tolerably close estimating densities by eye.

Some gotchas:


The meter's cell must be small (not Selenium), and have a flat bezel around it so it'll lie flush on the pasteboard to keep out stray light. I used a 70's-vintage Sears CdS meter from my junk-box. If lacking a flat bezel, cut a small piece of tubing or somesuch to block out ambient light.
Light-intensity varies over the surface of the light-table, so take measurements in the same location.
Florescent lights brighten over a few minutes as they warm-up, so allow 5-10 minutes of warm-up first.


Mark Overton

albada
01-27-2012, 09:42 AM
In this posting (http://www.apug.org/forums/viewpost.php?p=1286899 (http://www.apug.org/forums/viewpost.php?p=1286899)), Alan Johnson tested one of my developers-in-progress, called D316, and posted scans from his Epson V700 flatbed scanner. He kindly posted (mailed) the negatives to me, which arrived yesterday. Royal Mail is fast.

Here are two scans of the same negative developed in XTOL 1+1 at EI 400. The second scan was done with a slight reduction in analog gain to attempt to match contrast with the D316 scans that follow. The XTOL scans:
45131 - 45132

And here are scans from my test-developer D316. The left is EI320, and the right was the thinnest neg on the strip (unknown EI):
45133 - 45134

The scanner's settings were identical in all these scans, except as noted for the 2nd XTOL scan. The scanner was manually focused on the car's wheel.
Alan, do you recall the EI of the thinnest neg? It looks like you were bracketing in 1/3-stop increments, which would make it about EI 500.

Anway, it appears to me that D316 has finer grain than XTOL in all cases. But this was XTOL diluted 1+1; it would be interesting to compare with XTOL undiluted. In Alan's scans, XTOL had finer grain. I think that's because the focus of a flatbed scanner varies across the glass. Under extreme enlargement, the scan-lines for Alan's XTOL-image were blurred compared to D316, revealing uneven focus.

Mark Overton

Alan Johnson
01-27-2012, 12:50 PM
Mark,
The thinnest D316 negative was shot at EI=500.
As you know more about flatbed scanners than me I am happy with your explanation.
I wait with interest to hear if the part B can be made up with say 2 heaped teaspoons of sodium sulfite in 500ml when the part A is decided.

albada
01-30-2012, 01:49 PM
I've been experimenting with Dimezone S. Compared to Phenidone, I'm finding that Dimezone S:


Gives lower fog.
Gives a hair less shadow-detail (flatter toe).
Grain is about the same.
I need twice as much Dimezone S as Phenidone to get the same density. I even mixed a 2nd PG-based percentage-solution in case I botched the 1st. Same results from both: Need 2X. That's odd, because formulas typically use a ratio around 1.3X, not 2X. I mixed the 2nd solution at about 35-40C, so temperature-damage isn't the cause. Any idea what happened?

Mark Overton

Photo Engineer
01-30-2012, 01:54 PM
Maybe activity is not linear with pH?

IDK for sure. It may be the combination of ingredients.

PE

albada
01-30-2012, 02:34 PM
Maybe activity is not linear with pH?
IDK for sure. It may be the combination of ingredients.
PE

Hmm. My experiments have been at pH 8.0, which is low enough to be chancy. You are saying that the pH-activity curve might fall more rapidly for Dimezone S. I hadn't thought of that.
I'll have to try some experiments at pH 8.2. In particular, I'll try mixing some Mytol to verify its density is as expected, which will also verify that my Dimezone S is okay.

The formula is (or is similar to) this: http://www.apug.org/forums/forum37/98430-improved-version-ds-10-ryuji-suzuki-32.html
I found that changing the .05g of Phenidone to .1g of Dimezone S gives the same density, and in fact looks identical to XTOL in all respects.

Mark Overton

Photo Engineer
01-30-2012, 04:17 PM
Go for it Mark! If it looks like XTOL you are in the sweet spot.

PE

albada
02-03-2012, 10:39 PM
Do potassium/sodium thiocyanate have any role in a general purpose developer? In an experiment, I went low on sulfite -- only 22 g/liter -- which caused the test-strip to be thin. So I added 0.4 g/liter of potassium thiocyanate, and tried again, hoping the extra solvent would uncover more latent sites. No go; the result was even thinner.
What other chemicals can uncover latent sites? Does sulfite have a monopoly on this?

Mark Overton

Photo Engineer
02-03-2012, 10:49 PM
Mark;

You are pitting or comparing solvent effects vs pH effects. You must differentiate between the two

PE

albada
02-03-2012, 11:29 PM
Mark;
You are pitting or comparing solvent effects vs pH effects. You must differentiate between the two
PE

(As I'm typing this, I'm listening to your radio program)

I've created an array of developers changing only sodium sulfite and sodium metaborate, keeping pH and dev-time constant. The density-curve is flat at 75 and 45 g/L. There's a slight drop at 33, and a big drop at 22. All at pH 8.0. Any idea why the curve drops at 22? (I mixed the 22 version twice to be sure it wasn't my error.) I'm guessing there's not enough sulfite to uncover latent sites. Or maybe TMY-2 just doesn't like that mixture of alkalis?

Mark Overton

Photo Engineer
02-04-2012, 10:59 AM
I'm guessing that the film you are using is made of 2 or 3 emulsion components. The one that drops has a component in it that is sensitive to these conditions. As this is a guess, the proof would be to test it with another film and see if the problem remains or vanishes. If it vanishes then the film you used first is sensitive to those conditions and it means that not all films can go through developers of that type.

If the problem remains then it just proves that the developer in question is no good. ;)

And, if I am right, then it indicates a typical problem seen in small development labs. You have to design a developer that will work evenly with all films and doing that is expensive.

I hope you enjoyed the podcast.

PE

Michael R 1974
02-04-2012, 11:25 AM
Mark, by the way I noticed APUG member Greg Davis is selling a densitometer over in the classifieds if you're interested.

albada
02-04-2012, 10:45 PM
Mark, by the way I noticed APUG member Greg Davis is selling a densitometer over in the classifieds if you're interested.

Thanks for the pointer. Looks like somebody else snarfed it first.

I've been playing with what I call SMAP developers. SMAP stands for Sulfite-Metaborate-Ascorbic-Phenidone. It's surprising how much you can do with just those four components. Well, here's a combo that's similar to the D316 that Alan tested, and works great:


Sodium sulfite ................. 45 g
Ascorbic acid .................. 4.5 g
Sodium metaborate ........ 2 g
Phenidone ...................... 0.05 g
Target pH=8.0. Starting times are twice XTOL's times. For TMY-2: 13 min @ 20C.



D316 has 2.2 g of metaborate and this has 2 g; that's the only difference. This formula can be formulated as a concentrate (with sulfite added separately). It gives grain that's at least as fine as XTOL's or a hair finer, a hair better shadow-detail, and slightly worse sharpness. This formula appears to do little or no sharpening, and sharpening makes quite an improvement when something isn't in perfect focus. XTOL has reasonable sharpness, and I'd like to know why.

That's my question: What is in XTOL that causes sharpening?
Perhaps Dimezone S is sharper than Phenidone? I've done some experimenting with Dimezone S, and want to get back to it.

I know everything is a trade-off, and I'd be willing to have a little more grain to gain some sharpening.

Mark Overton

EDIT:
I discovered why XTOL had better sharpness: It was the first frame on the roll, and the film there had some bend in it which changed focus there a little. False alarm. In other places on the neg, the difference in sharpness is barely perceivable, but still in XTOL's favor.

Gerald C Koch
02-05-2012, 09:23 AM
Mark.

The increase in sharpness of Xtol is due to the nature of ascorbic acid. The oxidation products of this developing agent inhibit further development while those of say hydroquinone encourage further development. Sharpness is a product of less infectious development.

Jerry

Rudeofus
02-05-2012, 09:55 AM
Jerry, Xtol uses Dimezone S (similar to Phenidone) and ascorbic acid, just like Marks recipe above. What I do notice, though, is that Mark uses a ratio of ascorbate to Phenidone of 90:1, and he has enough sulfite to renew used ascorbate. If Mark wants sharpness aka edge effects, he needs to design a developer which breaks down locally from heavy use. He can do that either by using a higher dilution, by weakening his buffering (less ascobate and metaborate for same pH), reducing agitation or by making sure that oxidised ascobate won't get replaced&restored (less ascorbate&sulfite). As one can expect, all of these measures will have an impact on grain size and/or speed.

To be honest: designing a developer, using only four easy to obtain components, which smacks Xtol in grain, sharpness and speed in more than very few special cases sounds like a very ambitious task. Attempting it may teach us a lot about developers, though, even if we never reach the declared goal. I've home brewed ID-68/Microphen in the mean time and got good looking negs from Delta 400 @ ISO800. Once I get my pH meter (in 1-2 weeks) I will definitely give your recipe(s) a shot either with TriX or Delta 400/3200. I wouldn't dare to brew a pH 8.0 developer without a pH meter.

Richard Jepsen
02-05-2012, 10:13 AM
I shoot maybe one roll a month in 35mm, and I can't use my 5 liters of XTOL before it goes bad. A concentrate that gives XTOL-quality would be perfect for hobbyist-shooters like me,

I also can not use 5L in 9 months. Find another photo friend and split 5L of XTOL.


There is no money in darkroom products. At this point and time, there is not.

We are at the end of an industry. What a great job men and women did to improve photographic products for nearly 2 centuries.

Equipment now sells for pennies on the dollar. The best is affordable. Its a great time for a serious hobbyist to keep printing beautiful, unique, gelatin silver prints. Its worth doing. Everyone can do digital...

Alan Johnson
02-05-2012, 10:37 AM
I don't think you need to use dimezone-s in a propylene glycol concentrate because phenidone will not hydrolyse in propylene glycol, IIRC there are reports of PC-TEA concentrate lasting for years.
In water solutions in a full stoppered bottle I have found the phenidone in Mytol does hydrolyse and in long stored water solutions dimezone-s would presumeably have an advantage but that is not the case here.

Michael R 1974
02-05-2012, 11:40 AM
I know everything is a trade-off, and I'd be willing to have a little more grain to gain some sharpening.

Mark Overton

EDIT:
I discovered why XTOL had better sharpness: It was the first frame on the roll, and the film there had some bend in it which changed focus there a little. False alarm. In other places on the neg, the difference in sharpness is barely perceivable, but still in XTOL's favor.

Mark, regarding grain/sharpness, perhaps also consider the lower activity of your formula vs XTOL, the longer development times allowing more solvent action. Not sure.