High Acutance Develper

[Ian Grant]

In his book "Photographic Processing Chemistry" (1974 Focal Press), L.F.A. Mason lists a typical High Acutance Developer.

This may possibly be the formula for Hyfin, which was Ilford's High Acutance developer, available from 1961 until the early 1970's. Mason calls it a typical formula:


High Acutance Developer

Metol 0.5g
Sodium Sulphite (anhyd) 5g
Sodium Carbonate (anhyd) 5g
Water to 1 litre

Development times 15-25 minutes
Requires a minimum of 600ml of chemistry per 35mm or 120 film.

Mason notes that additions to the formula have been proposed, either 0.1g/litre Potassium Bromide or 5ml of 0.0001% Potassium Iodide solution. (He may be referring to other similar formulae like FX-1 etc)


Hyfin was sold in packets containing 5 sachets of developer each one making up 600ml of solution. I have two packets of Hyfin & will weigh the contents of a scchet next time I'm in the UK.

Hyfin instructions were:

Pan F & FP3 - 18 minutes @ 20°C
Continuous agitation for the first 10 seconds then 5 seconds every minute.
Gives 1 stop more effective film speed



In the early 60's there were 3 High Definition devopers availabe in the UK, lford's Hyfin, Kodak's High-Definition Developer & Johnson's Definol.

It's no co-incidence that Hyfin & HDD are very similar to Beutler's High Definition developer, sold as Neofin Blue, and another similar developer is Crawley's FX-1 formula.

The major differences are that Beutler has 1g Metol/litre & Crawley's FX-1 only 2.5g Carbonate + 15ml 0.0001% KI, compared to the formula above. The decrease in the Metol level compared to Beutler is likely to increase the edge effects & acutance further.

The addition of Potassium Iodide is likely to have little or no effect now as most modern films contain far higher levels in their emulsions, particularly Tmax & Delta films. It may have been more important with certain films Crawley speculates that it was needed in HDD for Pan-X

Mason would have known Crawley and his work, Ilford began manufacturing his chemistry for Paterson around 1963.

Ian

[2F/2F]

Instead of doing it the way that was posted, I am thinking of:

4 g metol
40 g sodium sulfite
40g sodium carbonate
water to 1 L

...to make a stock solution that is then diluted 1:7 to make a working solution. It would be easier for me when doing multiple batches the same night (primarily sheet film developed individually in a tray).

This developer working solution seems to have similar chemical concentrations as would D-23 1:15, with the addition of just as much sodium carbonate as there is sodium sulfite.

What I mean is:

D-23 1:15 contains approx. 0.5 g metol, and approx 6 g sodium sulfite per liter (0.47 g and 6.25 g respectively, to be exact).

This formula contains 0.5 g metol, 5 g sodium sulfite, and 5 g sodium carbonate per liter.

So, it is basically a highly dilute D-23 with added sodium carbonate.

Is that added carbonate just serving the function of making the highly dilute D-23 more active?

Any idea of what the pH "should" be, Ian?

[Ian Grant]

No idea of the actual pH but it will be be considerably higher than D23, possibly > p11 compared to around maybe pH 8.5 for D23. So the two developers work quite differently, D25 reduces the pH of the developer even closer to pH7 by adding Sodium Metabisuphite to D23.

A stock solution has a very short life, and is not recommended for storage by Ilford with Hyfin, or Beutler, Crawley etc who's developers are all quite similar. There's insufficient sulphite compared to the Carbonate to preventthe the Metol oxidising in solution. Crawley suggested a 2 part stock solution for a developer like this keeping the Carbonate separate.

Ian

[2F/2F]

Thanks, Ian. In that case, I'll mix it into two parts, and will probably use them up rather quickly by doing a few batches in a night.

It raises the question in my mind as to whether D-23 would work at a 1:15 dilution, or whether carbonate must be added to convert it into this other brew in order to get it to work.

[Ian Grant]

D23 might work at 1:15 but the development times would be extremely long, you'd need a large volume to ensure sufficient developing agent and then the sulphite level would be low in solution so that you'd almost certainly start to get oxidation of the Metol before development finished.

But then D23 + Carbonate is close to Beutler etc and the higher pH changes the activity very significantly.

Ian

[Photo Engineer]

With that amount of Carbonate, and considering that you have to neutralize the acid in the Metol, I doubt if the pH is much above 10.

PE

[Ian Grant]

It's almost impossible to guess without a pH meter, but the Metol level is low, so even pH10 would still be considerably higher than D23 and the developer far more active.

Ian

[Alan Johnson]

Mason's formula is very similar to FX-1 without iodide.
Its pH will be around 11.5
Developing times for FX-1 at 68F:
Pan F 12m, FP4 13m,T-max 100 20m
Plus-X 12m, Adox 50 17m, Adox 100 ~17m
The last three are old emulsions and give good edge effects if agitatated only every 3 min and the development extended by 50%.Medium format is better as the resolution is not very high,but the prints have an interesting unusual appearance of being made up of sharp grains with slight haloes round dark objects.

[gainer]

Some points I have learned about sharpness, etc. Your eye will see Mackie lines at a knife edge that has no intrinsic Mackie lines. The truest sharpness is obtained at the edges where there is the steepest gradient between light and dark. If you want to see if the mackie lines you perceive are in the image or in your vision, look at an edge with a magnifier.

I had a go-round some years ago with an advocate of Acutol. I was brash enough to tell him that PC-TEA was as good as Acutol. In fact, the advert showing the comparison between the Acutol characteristic curve and others was not possible, and in any case not desirable. I compared the actual characteristics of the Acutol and PC-TEA and showed that there was very little difference. I sent him a complementary sample of PC-TEA stock to play with. I have heard no more from him.

So, before you mourn the loss of Acutol, try PC-TEA. You might like it.

[Tom Kershaw]

Patrick,

What benefits were Paterson claiming for Acutol?

Tom

[Ian Grant]

Acutance, it was OK but the grain was more than Aculux or ID-11 and tonally it wasn't quite as nice. But the negatives were sharp.

Ian