Would I be missing anything if I use D-23 instead of D-76?

snusmumriken said:

I don't have that paper available, but taking the quote at face value, isn't he comparing metol in MQ developers with phenidone in PQ developers?

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Increased contrast with hydroquinone is also found with metol as illustrated in p173-177 here:

OK and thanks for the answers koraks and Yeshizu. I am a little clearer, I think, on why we can say that each film requires only 0.12g of Metol for development in theory as it were but there is no way that can be spread across all of a film properly in less than a very long time or seemingly even an eternity which isn't practical

Effectively you need a lot more Metol than is theoretically required for it to cover the whole film sufficiently in a reasonable time for practical development to take place

So from this might a reasonable conclusion be that the nature of Metol's action requires much of it to be wasted i.e. you have used with 4 films the full 1L of developer and its 7.5g of Metol and yet there is something like 7g of Metol that was not used at all?

There remains for me at least the practical question of what may still be the scope for scaling down in terms of the amounts of Metol and Sulfite. Maybe the answer is none and this was determined during testing by Kodak which was why Kodak stated that it was 7.5g of Metol and 100g of Sulfite? This was the right quantities of both chemicals to meet the requirements of D23? As Yeshizu says economising on the two quantities might be possible but you would end up with a different developer with different qualities

So in terms of "practical" economy it may be that the limits are 8 x35mm films or 4 x120 films with stock D23
using a Jobo rotary processor but only 4 and 2 respectively using inversion agitation

At 1+1 using a rotary processor the D23 stock involved drops to 70ml for a 35mm film and 120ml for a 120 . While 1+1 changes the qualities of subsequent negatives anyway, it raises the question of whether only 70ml stock is sufficient to get the same negatives as would have been obtained with inversion agitation with 125ml of stock?

Is the answer to that a Yes on the basis that the additional agitation from a rotary processor makes up for the lower stock quantity or No because the halving of stock to 70ml makes the D23 behave differently such that you would get usable negatives but they would not be the same as those from a 1+1 dilution using inversion agitation where the stock is 125ml?

Comments on my speculative thoughts are welcome

I have enjoyed this as a learning exercise

Thanks

pentaxuser

Based on previous formulas, I believe there are several approaches:

1. As you mentioned, agitation and proper loading can help reduce the required liquid volume.
2. Replenishment restores the working solution to its normal concentration after use.
3. Accepting some performance differences for lower usage—for example, switching to a developer optimized for low-concentration, high-alkalinity conditions, renaming it as Rodinal.
4. Adding a less ideal but inexpensive reducing agent to regenerate oxidized Metol, maintaining its concentration (part of superadditivity). For instance, use 2g Metol with more hydroquinone as in D-76.
This effect is more pronounced in phenidone-ascorbic acid developers, where phenidone can be used at mg/L levels, but continuously regenerated by about 2g/L of ascorbic acid. Compared to using phenidone alone at 1–2g/L, ascorbic acid is inexpensive, widely available, and non-toxic. If use 10 mg of phenidone per roll, 5 grams of phenidone can develop 500 rolls.

snusmumriken said:

I've been pondering the question posed in the title of this thread (Would I be missing anything if I use D-23 instead of D-76?). It almost boils down to 'What did hydroquinone ever do for us?'

My experience of metol-only development is chiefly with Thornton's 2-bath formula. For the vast majority of scenes, I get negatives that print straight or with minimal manipulation on grade 2 or 2 1/2 (Ilford Multigrade Classic). If they don't, it's usually because I have cocked-up the exposure. So why would I need more contrast? If I was routinely having to use grade 3 or higher, I might understand, but that's not the case.

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Price! Based on my current chemical sources, if I set the price of 100g phenidone at 100, the price of metol is only slightly lower (approximately 95), hydroquinone is about half the price (around 45), ascorbic acid (chemical grade) is roughly one-seventh (about 15).

On the Photoformulary, phenidone 10g is $14.95, metol 100g is $16.95, hydroquinone 100g is $8.95, and ascorbic acid 100g is $12.95.

While prices vary by location and package and grade, it is clear that, when producing and packaging in large quantities, using 2g of metol plus 5g of hydroquinone is significantly more cost-effective than using 7.5g of metol alone. Manufacturers like Kodak would seek to reduce raw material costs wherever possible, if they can provided product quality remains unaffected.

Yezishu said:

Price! Based on my current chemical sources, if I set the price of 100g phenidone at 100, the price of metol is only slightly lower (approximately 95), hydroquinone is about half the price (around 45), ascorbic acid (chemical grade) is roughly one-seventh (about 15).

On the Photoformulary, phenidone 10g is $14.95, metol 100g is $16.95, hydroquinone 100g is $8.95, and ascorbic acid 100g is $12.95.

While prices vary by location and package and grade, it is clear that, when producing and packaging in large quantities, using 2g of metol plus 5g of hydroquinone is significantly more cost-effective than using 7.5g of metol alone. Manufacturers like Kodak would seek to reduce raw material costs wherever possible, if they can provided product quality remains unaffected.

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My cynical alter-ego would like to believe this, but the Ilford Manual of 1958 (revised 1966) specifically said, "The success of these mixtures depends upon the fact that their photographic properties are superior to those of the components taken separately" [my emphasis]. Is the explanation that in 1966 emulsions needed that extra contrast, whereas with today's emulsions we don't really need hydroquinone but it makes good manufacturing economics?

Alan Johnson said:

Increased contrast with hydroquinone is also found with metol as illustrated in p173-177 here:

Developing The Negative Technique : Kurt I. Jacobson, Ralph Eric Jacobson : Free Download, Borrow, and Streaming : Internet Archive

Eighteenth edition, revised, updated and reprinted. Epson V750, Vuescan, ScanTailor, Adobe Acrobat

archive.org

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Sure, yes, I have that book and I understand about super-additivity. But my question was, why do we need that extra contrast if in most circumstances metol alone produces a negative that prints on Grade 2 or 2 1/2?

snusmumriken said:

Sure, yes, I have that book and I understand about super-additivity. But my question was, why do we need that extra contrast if in most circumstances metol alone produces a negative that prints on Grade 2 or 2 1/2?

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Some (not all) report that D-76 (or ID-11 etc) can be used to provide more highlight contrast than D-23, and more sparkle:

snusmumriken said:

My cynical alter-ego would like to believe this, but the Ilford Manual of 1958 (revised 1966) specifically said, "The success of these mixtures depends upon the fact that their photographic properties are superior to those of the components taken separately" [my emphasis]. Is the explanation that in 1966 emulsions needed that extra contrast, whereas with today's emulsions we don't really need hydroquinone but it makes good manufacturing economics?


Sure, yes, I have that book and I understand about super-additivity. But my question was, why do we need that extra contrast if in most circumstances metol alone produces a negative that prints on Grade 2 or 2 1/2?

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Uh, I want to say that price is one obvious factor from my perspective, but not everything else is equal. Ian mentioned some considerations at the time:


These factors may depend on the situation—for example, when I'm mixing for one-time personal use, I don't care about storage stability, or whether the developing time increases by 50%. The difference in cost per batch is also negligible to me(how many rolls can I shot each year?). But these factors might be important in commercial settings. Another example is the use of very tiny additives in commercial developers. These aren't as popular in personal mixing, because accuracy issues can lead to significant differences (for instance, if a formula calls for 3mg of something in 1L solution—if I have to mix 500 ml new solution each time, I may rather use a formula that doesn't require such precise measurements).

Yezishu said:

if a formula calls for 3mg of something in 1L solution—if I have to mix 500 ml new solution each time, I may rather use a formula that doesn't require such precise measurements

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If I had reason to use a developer that called for this (like the "homeopathic" amount of potassium iodide in one formula or another) I'd start by making a stock solution of known strength in a photographically inert solvent that lets the solution store well -- distilled water for things like potassium iodide and other simple salts, 91% isopropyl or propylene glycol or similar for active chemicals like phenidone. If I have a 1% solution w/v, then 1 mg is 0.1 ml -- easy enough to measure with a suitable syringe. Honestly, though, as home-mixed developers go, any advantages over D-23 are very small.

Dektol is a pretty nice developer for film, also. Especially for bumping up the contrast a bit. I also use Ilford's Universal PQ developer for this reason.

I use to use Microdol-X for Panatomic-X and later for 4x5 film...used at 1:3 with the thinking that dilulting the developer would reduce the concentration of the silver solvent and get a little bit more sharpness at the expense of a little bit more grain.

Girders, Golden Gate Bridge
Developed in straight Dektol
4x10 carbon print

Vaughn said:

Dektol is a pretty nice developer for film, also.

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Especially if fine grain isn't a primary driver.

Vaughn said:

I used to use Microdol-X [1:3] for Panatomic-X ...

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Same here.

I hold that fine grain developers are for fine grain films.

As stated before, I think TMax-100 in Microdol is the finest grain combination outside of Tech Pan.

Contrary to popular belief, using Microdol at 1:3 doesn't result in coarser grain with TMax-100. The grain does, hoewever, get a mushy appearance compared to FS - but to see it you have to enlarge 35mm to 16x24" and examine the print with a 10x loupe. At FS Microdol's grain has a nice salt-and-pepper texture, a bit like Plus-X in D-76 1:1.

Using Microdol 1:3 does preserve TMX's film speed, unlike FS where I find Microdol/TMX looses a stop and a half.

Microdol with TMax used to produce dichroic fog but I haven't seen that recently. Which is good as my supply of Microdol-X has run out and I am back to using plain-ole DIY Microdol.

Unfortunately the creamy large-format-like look of Tech Pan doesn't appear with the TMX/Microdol combination even though the grain is comparable. With Tech Pan the LF look begins to fall apart at anything larger than an 8x10 print.