Kirk, you were right! I re-ran the precipitation-experiment at 20C (instead of 30C), and sure enough, slight cloudiness became visible after 40 min instead of 20 min. That means at 24C, it'll be 30 minutes, so this rule applies to the concentrate:
Originally Posted by Kirk Keyes
"If using hard tap-water, develop promptly, making sure development is finished within 30 minutes after mixing."
But I'd like to do better than that, so I'll investigate chelating agents.
I also waited one hour and then developed a test-strip to see what harm this cloudiness does. I'll scan it in 1-2 days.
@Relayer: I haven't forgotten your request to test your modified formula. I'd like to in a few days as time permits.
Originally Posted by albada
I was still experimenting with my borax-carbonate version. LegacyPro 400 5.5min look ok. my other experiment is decreasing amount of sodium sulphite from 90g/l to 30g/l. amount of borax is same, but I need increase amount of carbonate for correct pH 8.3. formula:
Sodium sulfite 30g
Ascorbic acid 8.5g
Sodium carbonate 3.3g
compared to 90g/l version this developer give less density for same time. more grainly, but sharpness is excellent. sample images for LegacyPro 400 5.5min in attach
Thanks for the work on this, I've wanted to try XTOL but making 5 ltrs is impracticable. I'm about to purchase the chemicals and the Sodium Metaborate (Kodalk) I can obtain is 8 mol. Could you advise on any correction to the amount of this to use, although I did Chemistry that was over 35 years ago!
Sulfite helps the developer to develop faster, so when sulfite is reduced, density will decrease, even at the same pH. You need to develop longer if using low sulfite.
Originally Posted by Relayer
6.3 g of Borax has the same number of boron atoms as 6.7 g of metaborate, but it has much fewer moles of molecules, so I think buffering will be worse. I suggest increasing acid and alkalis to improve buffering like this:
sulfite=90, ascorbicAcid=9, borax=10, s.carbonate=??, phenidone=0.1
Adjust s.carbonate to give pH=8.3. More than 10g of borax would be better, but it might take too long to dissolve.
The left scan in your images looks like the scanner was slightly out of focus. It is difficult to focus scanners accurately to measure grain. Can you re-scan that negative with manual focus on that part?
Firstly, Welcome to apug! (I notice this is your first posting).
Originally Posted by richydicky
You'll need 9.1 g of sodium metaborate 8 mol.
The ratio of the molecular weights of 8 mol and 4 mol = 137.88/101.83 = 1.354, which multiplied by 6.7 gives 9.1.
8 mol contains more water than 4 mol, so if you're mixing it into propylene glycol, I suggest letting it sit for 15 minutes at 90C to steam-out the water.
Don't let it get much over 90C or the PG itself will evaporate. Don't ask how I know.
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What's in your tap water? Your local water bureau can tell you that. PE has said that Kodak had water with extra minerals found in some municiple waters on tap for use in their lab testing!
According to my shower, plenty of calcium. We get an annual report from the water district, and I'll look closer next time.
Originally Posted by Kirk Keyes
Last night, I let tap-water-based developer sit for an hour at 30C, which is roughly equal to two hours at 20C (thanks again for that correction). The test-strip shows no sign of speckling, despite obvious cloudiness in the dev. BTW, the precipitation was still staying in suspension, so it hadn't gotten far enough along to start settling to the bottom. This dev will be used soon after mixing, so I don't think any precipitation will progress enough to cause harm.
But remember that white cloudiness and scale in the concentrate (not water-solution) that I reported a week ago? It was triggered by mixing-in the Dimezone last, but did not occur when mixed first. Well, it even occurred in the concentrate where the Dimezone was mixed first. It just took a week to start. This also happened months ago with a highly concentrated dev I tried. But it has not happened in less concentrated samples that are six months old, nor has Alan Johnson reported it about his bottle of D316.
If you define "concentration ratio" as GramsOfPowders / MlOfFinalVolume, then the failing samples had ratios of .46 and .63, and the successful samples had ratios of .35 and .33. So I'm suspecting that when concentration ratio gets much above .35, the concentrate becomes susceptible to this crystallization-problem that PE described here. If so, then I need to reduce concentration, and I have some ideas for that. One is to reduce the ascorbic acid some, which will also reduce the metaborate. Another is to replace some of the metaborate with TEA. Or one could simply add more propylene glycol. If somebody has suggestions about this, I welcome them...
Just to confirm that D-316 is still clear with no precipitate at 6 months old.
It has a concentration ratio (2.2+4.5)/20 = 0.335
Get your hands on potassium sulphite or potassium metabisulphite (and react it with potassium hydroxide beforehand) if you want to make a high-sulphite concentrate.
I've made a very high phenidone-ascorbate concentrate, but using potassium ascorbate. React the AA prior with a potassium salt like KOH. Shouldn't need as much sulphite for preservative with high ascorbate content. If you want to add salicylic acid, just use supermarket aspirin, it will hydrolyse in solution to salicylate.
If then the only role left for sulphite is to act as a fine grain solvent. You could use a very small amount of potassium thiocyanate (as in a non-highlight clearing/non-reversal amount for the process times).
My current concentrate is a bit different I made is similar, 4-aminophenol, potassium ascorbate and CD-2, still good after over a year, with some floating precipitate (saturated solution, like this since fresh). It is 1+24 to 1+49 dilution (20 min for HP5+ etc at 1+49), produces a negative that has higher local contrast with better micro details, but prints on a higher grade filter for the same black to white range (good for high contrast subjects already printing at 0), has more accentuated grain though.
If you want a very high keeping life of concentrates, if you're going to split it into a 2 part solution anyway, making the part with the developing agents pH 4-6, with potassium metabisulphite and/or ascorbic acid etc, should increase the shelf life due to lower pH.
Last edited by Athiril; 07-27-2012 at 11:30 PM. Click to view previous post history.