Dilution ratios What does it do?

Thinking of trying a different B&W film stock, and also in how we are developing the stock we are using now..
But have confussion on dilution ratio's. What are these ratio's really doing?
OK.. forgetting about agitation for the moment, say using D76 stock, does it give you a better development 'look' for a specific need? Or does it just decrease the developing time? (Can't believe that!)
Then there's Hc110, the other developer we use, has so many different ratio's, what's the advantage?
Background:
Have been doing D76 1:1 & HC110 at dilution H, and got the timing and agitation, for the B&W film we are currently using to what we like, but now want to expand horizons.

With respect to XTOL, replenished XTOL gives better results and is more economical than dilution. When replenished is better and cheaper than one shot dilutions why dilute?

For solvent developers, like D-76, the stronger dilution will result in more softening of the grain and a bit less acutance; the weaker dilution gives greater acutance but more pronounced grain (Kodak states this very clearly...). Otherwise, dilution affects developer activity, which, as you point out, increases development time. The obvious advantage here is to keep development times from being too short, which can result in uneven development.

Another consideration is fog. Very active developers often produce more base fog. Diluting the developer can help reduce the amount of base fog.

Also, having less of the developing agent per unit of volume also can promote compensation effects where the developer exhausts in areas of high density before the developer in the less dense areas, resulting in a kind of proportional decrease in development as a function of exposure. This, of course, is dependent upon agitation technique; too frequent agitation and the developer in the denser areas has no or less time to exhaust. This is also somewhat developer dependent.

Best,

Doremus

HC-110 was originally created to serve the commercial developing market. It was designed to be a usable replacement for a number of different developers - most of which were commonly found in deep tank, continuous replenishment systems. Kodak was able to market it to different users and to say things like - you can replace the developer in your D-****** line with HC-110 dilution X and your developer in your D-****** with HC-110 dilution Y, which allowed the labs to reduce the size complexity of their inventory.
Home and individual users cottoned on to the advantages of that flexibility - thus "unofficial" dilution H and 1+49 .

Note that what Doremus wrote is true, but "stronger dilution" means a smaller value second number. From strongest to weakest are:
1:0 (stock solution)
1:1 equal parts stock and water
1:2
1:3
Note that with D76, your highlights are likely to be overdeveloped and "blown out".

Most developers work better diluted, but give slightly more apparent grain, better gradation, "compensation", and accutance. Compensation is where the highlights are develped to a lesser extent than the shadows.

If you want a different look from what you are now getting, you'll see a bigger difference by going to a different class of developer than making changes to the dilution. Both D76 and HC110 are solvent developers, for fine grain; XTOL is also a solvent developer. Try going to a non-solvent developer (also called high definition developer) like Rodinal, FX-1, or FX-2. FX-1 is one of the highest definition developers, but the gradation is sometimes described as "soot and chalk", very low shadow values and overblown highlights (at its worst).

The answer can be complicated and depends on the particular developer. However in general it can be said that with dilution the development times will increase and acutance may also increase. The complexity of the problem is that not only does the concentration of the developing agents change but also everything else in the developer.

I used HC110 for years and found I liked the 1:63 ratio because of the slower development time. If you a consider scenes that might need a boost in contrast, a 1:31 mix could easily be over developed when going from say normal 6 to 6:30 minutes. However giving an extra 30 seconds for a normal 12 minutes is not that risky when using more dilute mix. The fill and drain time of your tank can have an impact on density and timing, going more dilute helps you reduce the impact a bit. Example: Fill 10-15 seconds, put on lid, start timer, begin initial agitation ,,, remove lid, Dump during last 15 seconds, pour in stop for 15 seconds... Strong developers are still working during those fill and dump times, and any mishaps amplify the errors on film.

Thanks for all the the replies..

voceumana said:

Note that with D76, your highlights are likely to be overdeveloped and "blown out".

Click to expand...

Hmmm.. are you talking any dilution, or just the stock solution? Don't think ever have ever blown out D6 highlights.

esearing said:

I used HC110 for years and found I liked the 1:63 ratio because of the slower development time.

Click to expand...

Yes, Dilution H, is what we use also, but with Arista 400 @ 200 out here in the sunny southwest, it has a tendency to blow out the sky.. but in shadowed scenes, has a look that appeals to me.
Because of this, we started using D76 1:1 and the sky highlights are good, but the look is softer.. One of the reasons wanting to experiment with this film stock we have, been using almost extensively, and finish up some 4x5 HP5+ that haven't shot since 2015, (Its refrigerated)
Time to graduate, seem to have learn how to shoot the MF and LF cameras, there developing sequence, so time to move on mack-duff.

I personally like a dilution of 1+49, Easy to measure. There is a 1+47 dilution which provides development times as the two dilutions are very close.

I should have said with "undiluted D76" the highlights are likely to be blown out. Diluting to 1:1 solves the problem.

Rodinal is a great example. Stronger ratios give more grain (I've tested the heck out of this, not an internet guess) and also move the "curve" around. I'm not a densitometer guy, but the shadows close up more, and the lower mids become more prevalent, around 1+25 to 1+35. This can be nice for portraits, as eye and face details can pop more, and the drama seems to go up a notch. 1+40, 1+50 - you get more low mids detail and open-ness, a bit flatter feel, less grain but plenty of sharpness still. In my testing with grade 2 or 3 fiber prints, the dilution difference is quite noticeable. When you look side by side, you'll tend to like a face in stronger dilution - so you need to open up fill light a bit when it's in your control. I've also found a 10% developer change correlates pretty well to a 10% time change, which is handy to know.