(101 to 161 of 161 replies)
imagesfrugales 11:45pm, 23 May 2011
Thanks to Rob (Robbek) for his inspiration. I used iodized kitchen salt as a restrainer substituting potassium bromde. About 6 g/l may be a good starting point for medium speed films, and 10 - 12 g/l for high speed films. Worked fine with FP4+ and HP5+, the latter even with Caffenol-C-L and semi stand development. No need to adjust anything else, the pH remains the same. Also much cheaper than peanuts. Bingo.

Maybe that's a real breakthough for people having problems getting bromide. And the FP4+ had a very clear base.

There's also a salt with iodates and fluorides. I didn't use that, but only iodized salt. Fluorides might cause some trouble, but don't really know.

First samples:

Cheers - Reinhold
(101 to 161 of 161 replies)
Hannu_E_K PRO 5 years ago
I'll ponder on it... If you have ideas, let me know. I'm working daytime 'CET' timezone, so don't expect too quick answers ;-)
f6point3studio 5 years ago
It may be that the Iodides and Chlorides are not so suitable for the Kodak T-grains.

- Certainly the Iodides will restrain AgI better than AgBr, but this may be very dependent on the emulsion (one should ask Kodak what's inside).

And if you take cranberries and stew them like applesauce, they taste much more like prunes than rhubarb does.

...you guys make my head spin.
RobbeK 5 years ago
The salt and Iodides (Iodates) work well on the PolypanF film.
Here the Chlorides may have a positive effect.

Eirik0304 PRO 5 years ago
Regarding TMAX films. I had great success with TMX, in fact its more or less bombproof in C-C-M. But have yet to get a good grip on TMY-2, very varied results indeed. The former needs no restrainer, whereas the latter does. I've only used KBr until now. I wouldn't say T-grain films in general are a problem, Acros works very well too. Maybe its just a case of TMY-2 not being compatible with our efforts to restrain it? Anyone got any older TMY to compare with?
Hannu_E_K PRO 5 years ago
I have, after the above attempts, realized the salt I have is double strength of Reinholds. Not paying enough attention...
ᛒᚢᛁ᛫ᛋᛁᛒᛁᚢᚱᚾ᛫ [deleted] 5 years ago
I just developed some Adox CHS 50 using 10g/l of the same salt as last time when developing the Adox Pan 25 and even tho they´re drying now I can already say that they look pretty wierd. They have a odd bluish foggy look plus the usual overall brownish stain to them and look extremely dense even tho I exposed them at ISO100 .. Give me 1 hour or so and I´ll have some scans for you!
ᛒᚢᛁ᛫ᛋᛁᛒᛁᚢᚱᚾ᛫ [deleted] 5 years ago
So here it is, didn´t come out as bad as I thought.. The CHS stains a lot more than other film and even more so using salt, some fog is evident in the (not so) clear borders of the negative but definitely usable.

Here´s a colorscan of the neg, no adjustments at all.

inetjoker PRO 5 years ago
The salt is not needed for slower films... Why add another problem?
ᛒᚢᛁ᛫ᛋᛁᛒᛁᚢᚱᚾ᛫ [deleted] 5 years ago
No restrainer in C-C-L and 4X5 = Uneven development..

Thats why! :)
inetjoker PRO Posted 5 years ago. Edited by inetjoker (member) 5 years ago
About Morton Iodized salt for you Americans.

Morton® Iodized Salt contains potassium iodide, dextrose to stabilize the iodide and calcium silicate which is an anti-caking agent. This product is fine for baking, cooking and for the table. However, because the anti-caking agent in this product is not water-soluble, we do not recommend this salt for some canning recipes as the calcium silicate may settle at the bottom of the jar.

This may also apply for other iodized salts you folks may use. I wonder if filtering the solution may be in order to remove the calcium silicate.

In 1924 Morton became the first company to produce iodized salt for the table in order to reduce the incidence of simple goiter. Dextrose is added to stabilize the iodide. Iodine is vital to the proper functioning of the thyroid gland and the prevention of goiter. Actually, the amount of dextrose in salt is so small that it is dietetically insignificant. Morton® Iodized Table Salt contains 0.04 percent dextrose or 40 milligrams per 100 grams of salt. Morton® Plain Table Salt contains neither iodine nor dextrose. All Morton Salt products containing potassium iodide are labeled as such.
ErikPre Posted 5 years ago. Edited by ErikPre (member) 5 years ago
Dextrose is a sugar, in oits own that is a restrainer (Ole Tjugum, APUG moderator).

Iodine also helps to prevent damage to the thyroid gland from nuclear radiation, like in Japan these days, they hand out KI-tablets, I'm sure.

In europe the caking agent is SiO2 - silicate dioxide. That stuff is so small (less than 1/1000 mm) that we need not concern ourselves, it is way smaller than what we call grain, I'd wager that is the same holds true for calcium silikates too.....

Thanx for the update, valuable datapoint.
Colusite [deleted] 5 years ago
I have also found a bit of Morton's to significantly help with even development.

These shots are on 120 Plus-X and developed with Reinhold's Caffenol C-M recipe with a bit of salt added 4g/l:

Crystal City

Spilt Coffee

Think I need to wash them some more - the second shot has a good bit of staining.

I used TF-4 alkaline fixer.
cwroe 5 years ago
Sorry if I missed it, but is there an updated recipe chart with salt?
Hannu_E_K PRO Posted 5 years ago. Edited by Hannu_E_K (member) 5 years ago
the "update" consists of insights in how much Iodine (the active component) there is in your salt. Some info is here:

The base data is about Swedish salt, but will have you realize that it might not be as simple "just add 5g salt per liter".
inetjoker PRO Posted 5 years ago. Edited by inetjoker (member) 5 years ago
The way I read it American Morton salt has almost double the Iodates as the European salt. Europe still has goiters. :-)
stragatto 5 years ago
Due to the reducing action of vitamin C and the Na2CO3 I think thar we can suppose that all the iodine, in whatever form is added, is reduced to iodide. The iodized salt of my nearby supermarket has 0.005% KIO3. The same label reports the iodine content: 3 mg per 100 g of salt. This is correct, because 5 mg of iodate correspond to 2,94 mg of iodine.
The calculation is easy:
iodine=iodate*(Atomic weight iodine)/(Mol. weight iodate), that is :
iodine= iodate*126/214.
Now i think that if we find the correct amount of iodine expressed as concentration, everyone can easily calculate the corresponding quantity of salt from the label data of the available salt. Moreover, I think that once we express the needed value in terms of iodine concentration, also other sources (e.g. iodine tincture) can be investigated.
inetjoker PRO Posted 5 years ago. Edited by inetjoker (member) 5 years ago
So say we put 100g of iodized salt in a liter of water where does that leave us? let us use this as a base line as we know more will dissolve in the water and that is if we use a solution to add to the developer and not the salt in it;s self. Thus this brings me back to a post I made a few months ago about using tincture of iodine in a solution to add to the mixture and was told it would kill the developer.
imagesfrugales Posted 5 years ago. Edited by imagesfrugales (member) 5 years ago
Hm, the molar masses listed in Wikipedia:

potassium iodide, KI: 166 g/mol
potassium iodate: KIO3: 214 g/mol

So the conversion factor would be only 214/166 = 1.28


So how do we calculate properly?

Maybe you can check the comments concerning Morton salt here? caffenol.blogspot.com/2011/05/iodized-kitchen-salt-can-re...

Thank you, Reinhold
inetjoker PRO Posted 5 years ago. Edited by inetjoker (member) 5 years ago
No let us make this easy .Say I dissolve x amount of Morton into one liter of water How many ML do I add to the y amount of developer? y to make it simple is 500ml. You all must remember Caffinol is something to teach people not chemist.

What is X into 1000 ML and what is y into the 500ml of developer.

Now if we are using the Mortin directly from solid what would we do I wanted to make it easy and just have a salt solution I could add to the developer.

Alchemist not chemist.
stragatto Posted 5 years ago. Edited by stragatto (member) 5 years ago
I proposed to calculate all as iodine (not as iodide) as is in the label of my salt, thatś why I used the factor 126/214. Even if really all the iodine is in solution is in the reduced form of iodide. If the salt contains both (iodide + iodate) I think that could be easier to calculate all them as iodine.
I made a worksheet where can be introduced the % amount of iodine, iodide and iodate, and the corresponding total of iodine is calculated.
Once introduced also the required mg/liter iodine, the corresponding grams per liter are calculated, along wih the grams of salt for a given volume of solution (e.g.300ml)

The required mg in terms of iodine are obviously the requred iodide mulltiplied by 126 and divided by 166. I can refine my worksheet adding the input as iodide mg/liter.
imagesfrugales Posted 5 years ago. Edited by imagesfrugales (member) 5 years ago
OK, I got it.

1 mol iodate contains 1 mol iodine
1 mol iodide contains 1 mol iodine

214 grams of iodate contain 1 mol iodine
166 grams of iodine contain 1 mol iodine
126 grams of iodine is 1 mol iodine

So the ratio is 126/214 for iodate and 126/166 for iodide.

PS: decimals in the sheet must be noted with a komma, so 2,5 instead of 2.5 f.e.

So the salt I use (iodate 2.5 mg/100g) contains 2.5x126:214 = 1.5mg/100g iodine. The brand is ChanteSel iodized salt from Lidl. I use 5 to 15 g/l of this salt.

I guess we are on a good way. Thanks a lot. Now we need data for other brands.

A more simple sheet where you only specify the used brand from a drop down list would be great.

PS: decimals in the sheet must be noted with a komma instead of a dot, f.e. 2,5 instead of 2.5

PPS: that translates to 0,3 to 1mg/l required iodine that I use.

PPPS: That's great
imagesfrugales Posted 5 years ago. Edited by imagesfrugales (member) 5 years ago
stragatto, could you add a % value as an alternative input. Many packages say f.e. 0,0025 % iodate

You are my today's hero!
Dcaffenol Posted 5 years ago. Edited by Dcaffenol (member) 5 years ago
thanks for pointing out that a salt solution can't be used as a fixer
i think it was patrick gainer that suggested over on apug that
it might work ... but i never tried it ...

sea water is about 10% salt ... with iodine and selenium and ...
would it have too much of "the other stuff" and not enough iodine to be used as a developing restrainer ?
i live near the sea and i was thinking of boiling some
sea water to kill the living stuff, and then making caffenol with unroasted beans and brine instead of tap-water ...
stragatto 5 years ago
The percentages are grams/100grams, so it is very easy to read 0,0025% as 2,5 mg/100g . I used OpenOffice Calculate italian version, so for me the decimal separator is comma. Do you see it as dot?
Anyway, I will think to other versions . A table with contents for most brands of salt should be added: at present I know for sure only 2 of them.
Hannu_E_K PRO 5 years ago
<Think... Groan... Think...> Ahh... Now I see - I got the molar weights wrong in my calculation!
(Note added to post in other thread to have people not use the numbers)

Now if we can make all calculations end in "x mg Iodine per 1000 gram Salt". (1000g = 1kg)

Then we can tell to create a water/salt solution with a specific Iodine content - which will be asy to measure up.

Just need to get it work in practice also :-)

Now, might it be possible to use the fact that 359g NaCl is soluble in one liter water?
That would be 35.9g per 100ml
<=> 3.59g per 10ml
<=> 0.359g/ml
Hannu_E_K PRO Posted 5 years ago. Edited by Hannu_E_K (member) 5 years ago
OpenOffice Calc: Tools > Options > Language > "Decimal separator key"
As this is a tick to mark "Same as locale setting", I really don't know if it is changeable within Calc.
Check Control-panel, Locale/Language/Country - settings.
Hannu_E_K PRO 5 years ago
For a list of selectable objects in OO:Calc, a description of how to do it is in the third comment here:
The remainder of the info might come in handy too ;-)
inetjoker PRO 5 years ago
We are working on it thanks people.
Hannu_E_K PRO Posted 5 years ago. Edited by Hannu_E_K (member) 5 years ago
After sweeping out my bogus calculation in the other thread...

I have been trying out the Calc-sheet above. But have hard to come to another conclusion than that there is something backwards:

The Lidl salt is stated to contain 2.5mg Iodine per 100g salt.
The Jozo salt has the double, 5mg Iodine per 100g salt.
... and seing it like this tells me that I should use HALF the amount of salt - agree?

But now, I tried to -fool-proof-verify- with the calc-sheet... it tells me that:
4.25 <- provided by me grams/100 of Potassium Iodate (KIO3) is the same as 2.5mg Iodine per 100g salt
With this salt I should add 15g salt to have a 0.6 mg Iodine per liter changed that 0.5 to 0.6 too, to get the 15 grams per liter .

Check: 2.5mg/100g => I want 0.6 / but have 2.5 = 0.24 (keep ratio) => Then 0.24*100g = 24g! (excel sheet is wrong - in my opinion)

And further If I change the input to contain 6.5 grams/100g salt of Potassium Iodide (KI) to get 5mg Iodine per 100g salt (which is the same as above, the salt I have).
Then the output changes, but in the wrong direction... 29.6g of salt.

The correct amount should be 12. Because there is double the amount of iodine in this salt (5mg/100g instead of 2.5mg/100g). So the logicla outcome is "half the salt of double strength".

I'll try to dig a bit more in the excel sheet to understand where it goes wrong...

Or, is it me again? 8-}
Hannu_E_K PRO Posted 5 years ago. Edited by Hannu_E_K (member) 5 years ago
Ahh.. There should be a
in cell C9

This changes the iodine concentrations created by the 5 to 15 grams of Lidl salt into some thing like 0.1 to 0.4 mg per liter (with a little slack).

I wonder if it wouldn't be more convinient to use a saturated salt solution and a syringe.

359g of salt can be mixed into one liter water, so adding 60g of salt into 100ml wold make 60-35.9 = 14.1g salt slur around at the bottom.
Using a syring on the water on top would then contain 3.59g/10ml.
So 20ml = almost 7.2 grams - seems easy... :-]
inetjoker PRO 5 years ago
I think I asked that the other day about a salt solution but it went off track.
RobbeK 5 years ago
stragatto Posted 5 years ago. Edited by stragatto (member) 5 years ago
Hannu, you're right: in C9 there should be =100*B9/E6. I am going to put in the server the correct version. Of course, the desired quantity can be measured as ml of saturated salt solution. But I prefer to apply a weight measurement, because I am not confident about the time necessary for reaching the saturation equilibrium in the solution. For measurement in terms of ml of saturated solution, I would suggest to prepare it about one day before the use, and to agitate it thoroughly some times after preparation.
ErikPre 5 years ago
The simple solution is to dissolve 30 grams in 100 ml, or in my case 75 gram in 250 ml. That will dissolve in all climates, except here in a cold cellar during the winter, but we know how to deal with that.....

10ml is 3 gram
50 ml is 15 gram

This is easy to do right, and easy to remember, and doesnb't confuse people with saturated solutions and what to do when you gets near the bottom. Easy does it!
Endemoniada PRO Posted 5 years ago. Edited by Endemoniada (member) 5 years ago
This was the result of doing Caffenol-C-M with 5g of Lidl iodized salt (0.0025%) and developing Kodak Tri-X 400 for 15min@20C:


Not bad, huh? I love how the clouds are visible even though the entire photo is pretty brightly exposed.

This recipe is definitely a keeper, and while I haven't got anything to compare to myself, I think the iodized salt really does the trick.

Edit: Someone commented on shadow detail in this photo, but I think the development really is quite good. It's my scanner that's fucking up my photos. See this photo (also compare in original size) to see the difference. The shadow detail is there (that's an untouched TIFF, which has lots of potential for adjustment), the grain is really nice, and the entire photo is evenly developed and with plenty of detail.
Hannu_E_K PRO Posted 5 years ago. Edited by Hannu_E_K (member) 5 years ago
regarding saturated solution...
You suspect it to be slower to get into solution as it gets closer to saturation?

Seems quite unsensitive to tempertaure according to the diagram (image) here:

hfandrep: You're right.

Second thoughts: It might be that putting the salt into solution frees the Iodine for vaporisation. See RobbeK's post above.

edit: a few hundred typos `8-i
Hannu_E_K PRO Posted 5 years ago. Edited by Hannu_E_K (member) 5 years ago

In this post you spoke about Iodine tincture,

Could you have a look on the package and tell what it reads regarding the content?
stragatto Posted 5 years ago. Edited by stragatto (member) 5 years ago
the iodine tincture is a medical standard everywhere, and 100 ml of tincture contain 5 g iodine plus 7 g potassium iodide. Translating all into iodine are 10,31 g. One ml tincture corresponds to 103 mg iodine. It is necessary to prepare an intermediated diluted solution, let's say 1:100 and calculating the ml of this solution to be added to our Caffenol mixture.
inetjoker PRO 5 years ago

I went back and found I had posted it in another group where this conversation is also ongoing.
ErikPre Posted 5 years ago. Edited by ErikPre (member) 5 years ago
Stragatto : for our purposes that would be a 10% solution, no?

Use as is, add 10 ml per liter for 1 gram, or 3 to 5 ml for a normal tankful. I'll be talking tio my MD when visiting this week if I need a prescription for iodine tincture, I have a log cabin, cutting wood for the winter, wood splinters in the hands are dangerous bacteria sources! hehe.

Going to the docter for dev. chemicals is hillarious!

PS the picture above from Martin, the street view did it, I'm won over by you salt addicts!
Hannu_E_K PRO 5 years ago
According to the current Calc-sheet:
> This changes the iodine concentrations created by the 5 to 15
> grams of Lidl salt into some thing like 0.1 to 0.4 mg per liter
> (with a little slack).

Say that you create an intermediate solution that contains 0.5mg Iodine per 20ml.
20ml is 1/50 of a liter => 0.5*50 = 25mg for a full liter.
That would mean to have one ml tincture diluted in 4 liters of water.
(take an extra step in diluting and you do not need to mix up that much).
inetjoker PRO 5 years ago
Now we are on the road.
Hannu_E_K PRO 5 years ago
But as above, for the salt solution: It might be that putting it into solution frees the Iodine for vaporisation. See RobbeK's post above.

If it does vaporise, it will fade from effective to nothing with time.
ErikPre 5 years ago
Given the concentrations of the different constituets in this salt, I bet the main effect observed comes from NaCL, ordinary table salt.

Has anyone for the sake of accurate observation ever done any side-by-side test between ordinary, non-iodized salt and this mix?

I'm asking because noone has done any side by side comparison to KBr....

Keep in mind that films are made mainly from AgBr with a little AgI (between 200:1 and 500:1) and paper from AgBr and AgCl (Chlorobromide papers), I have checked this up the restraining process is a lot more chemically complex affair than it is usually given credit for....
Chloressigsäureethylester PRO Posted 5 years ago. Edited by Chloressigsäureethylester (member) 5 years ago
Potassium iodide is a potent restrainer in the sub-gramm area... but...

I have to say that iodized table salt (at least here in Germany) ONLY contains iodate (and no iodide(!!!)) between 15 and 25mg (that are 0,015g to 0,025g) per KILOGRAMM(!!!).
When you add 4g table salt per liter devoloper that are only 0,00006g iodate/l.

There is a little chance that the caffeic- or ascorbic acid are reducing the 0,00006g iodate to ~0,000043g active iodide, but the concentration would be still too low to see anything noticable from the iodide, even if you put 100g table salt in your soup.

Anyway I tested it myself. Table salt works as an restrainer. So I think that NaCl is the active ingredient. Chlorine has also a lot of known crossaction towards bromine and iodine in chemistry, so that isn't that absurd.

There are other ingriedients in table salt which might play an active role in devolopment --> anti baking agents like calcium stearate. They are easy to remove if you like to test: Dissolve the salt first in a tiny amount of 20°C cold water and filter off the (much harder to dissolve) calcium stearate. Then pour the (now clear) solution into your soup.
stragatto Posted 5 years ago. Edited by stragatto (member) 5 years ago
my supermarket iodated salt contains 3 mg of iodine ( 5 mg of potassium iodate) in 100 g, that is 30 mg iodine per kilogram, i.e, 0.03 grams per kilogram. I use 15g/liter iodated salt, that means and it works well. Potassium iodate is a strongly oxidizer, so is very likely to be reduced to iodide by the excess of vitamin C. The amount of iodide is small, but it is in the range applied in some traditional developers as Crawley FX-1.
But ...
In the formula of Ilford Perceptol we have 30 g/liter of sodium CHLORIDE (and no iodide), that means 15 g/liter in his working dilution 1:2 or 10 g/liter in his work dilution 1:3 !
ErikPre 5 years ago
"Potassium iodate is a strongly oxidizer, so is very likely to be reduced to iodide by the excess of vitamin C."

Stragatto : at ROOM temperature and in the concentration of soda we are working with here? Doubt that.

More likely a multitude of equilibriums will be in action here, precluding many, if not all to go 100%, I can SEE that ascorbic acid is transformed, we get bubbles and i a few minutes time a light urine-like color in the mix.

I can see and smell! that coffe is transformed, after that nothing seem to happen when I add a healthy dose of KBr.

As Chloressigetcetc says Chlorine, Bromide and Iodide are all halogenes, they works similarly but not identically....

If you want something really active try fluoride, that will probaly turn all of the film totally black...........
RobbeK 5 years ago
There's something else imo .. all those halide anions seem to be silver solvents - one can not use 20g/L Iodide ofcourse but Chlorides are used in (ultra) fine grain developers .

Next is from the ChemCAS site (Microdol X : ultra-fine grain devel. ) :
============= Composition/Information on Ingredients =============

RTECS #:WE2150000
Fraction by Wt: 70-80%

RTECS #:VZ4725000
Fraction by Wt: 20-30%

RTECS #:SL8650000
Fraction by Wt: 1-5%

It is mentioned he risk of adding any silver halide solvent is dichroic fog and that MX contains not listed (MSDS) ingredients to prevent this ...
ErikPre 5 years ago
Good points Rob, and the dichroic fog you mentions is exactly what I would expect if one uses too much salt, and we have to remeber that iodized salt contains 1/4% iodide salts and nearly 99,75% ordinary table salt, NaCl, (give or take a few percent impurities...) which dissolves silver grains AND acts as a weak developer restrainer AKA anti-foggant......

So the really FUN thing here is that we add something that combat one kind of fog and creates another kind of fog at the same time.

I think much of the controversy we sees on the Net these days stems from the fact that using the Net as the only source of information, gives rise to fallacies: if the blind starts to lead the blind the outcome is given. Back in the day the text-books was written by people that was old, with several of decades worth of experience, therefore they avaoided the quick and dead sure statements, they presented a balnced overview, because they knew how difficult some of this is.

Photo developer theory has pages and pages written about fog and other blemishes in negatives. They all have different causes and remedies, and quick and dirty procedures (which we are stuck with, since the good old chemicals are no longer generally available) don't always cut it.

Personally I think the focus on table salt as a restrainer is both an eye-opener and interesting, but I think we got the wrong end of the bar this time, and focuses on a minor ingredient, instead of focussing on the 90+ percent ingredient.

I don't think the last word on this is written yet, but i DO welcome another household ingredient to our toolchest!
ErikPre Posted 5 years ago. Edited by ErikPre (member) 5 years ago
Lot of confusion out there, as usual many americans looses the grip when it comes to scientific measurements, and how to interpret them.

Some clain iodides to be effective in the "mg range" some other claim it to be highly effective "in the 0.1% range".

Others mention that ordinary table salt - NaCl with no iodine - is effective with 10 gram per litre in commercial developers.

Have anyone paused and considered what this means and tried to connect the dots?

KBr - Potassium bromide is the standard restrainer/anti-foggant used in the industry.

It is usually added between 0.5 gram to 1.5 gram per liter.

How much is that? It is between 0.05% to 0.15% and THIS IS THE INDUSTRY STANDARD.

Compared to the statement above, that iodine is effective in the 0.1% range, it is fairly clear idodide is roughly on par with bromide as far as restrant effectiveness goes.

Compared to cloride, at 10 gram per liter, which is 1% it looks as if cloride is 1/10 as effective as iodide and bromide.

Of one takes this into account when one tries to asses the JOZO salts, it is fairly obvious : 10 gram og JOZO salt has more than 95% of its effectiveness from chloride, and it is a safe bet that NEZO salt, which is withouth any added iodide, would be just as effective.

The reason is, even high concentrate LIDL-brand salt has nearly 99,75% NaCL and just 0.25% KI.

10 gram per liter total is 1% toatal restrainer added. 0.25% of that is just 0.025%. Compare that to 0.1% KBr....

In short if you can't find KBr, just buy ordinary table salt, add between 5 gram and 15 gram per liter and don't give iodides a second thought!
dnbprojects 5 years ago
With regard to KI (potassium iodide)...

I can confirm after some experiments today that KI in small quantities is an extremely effective restrainer!

I'll have more details once I've finished the test run in the next few days, but you will recall that with half-strength CCM - that is:

54g sodium carbonate decahydrate
8g vitamin C
20g instant coffee
water to one litre (hard water here, as it happens) and developing with a 2 minute prewash, 15 minute develop, 2 minute wash, and fix, all at 20C.

was producing usable but severely fogged images in 4x5 sheet Adox CHS 50.

I can report that adding 0.5g/litre of KI results in images which are visible but very faint. 0.25g/litre of KI produces similar images but with more density to them. This was pretty much as expected, based on reports I'd seen. No fog, though!

My next approach is to reduce the amount of KI on a half-at-a-time basis, so more results as I get them. I've already established that milligram levels either don't help or are masked by the NaCl present, so another half-dozen tests should nail it.

Hey ho, here we go...

dnbprojects 5 years ago
Aha! these results achieved by accident - I intended 50mg and got 5mg/litre... one day I'll learn to count.

The fog is present, but definitely diminished with regard to the earlier attempts. Next stop looks like 10mg/litre. (apologies for the slightly soft image - I'm also testing simultaneously a home made camera prototype and a hundred-year old lens; the focal plane is this side of the nearer tree instead of at it!)

0862 by dnbprojects

This is the negative, scanned with no correction to show the remaining fog on the edges.

0863 by dnbprojects
ErikPre 5 years ago
Where did you get KI powder?
ErikPre Posted 5 years ago. Edited by ErikPre (member) 5 years ago
The reaction mechanisme of a halogen-based restrainer is a lot more involved and complex than thought.

This can be glaced from the fact that a film emulsion is roughly

Water 10%
Gelatine 55%
AgBr 33%
AgI 2%

That means we have aboutr 15 times more KBr, so KBr should work at least 15 times more effective than KI to start with....
dnbprojects 5 years ago
Got the KI from eBay - Scuddlebutt3 was the supplier though he's not listing any at present.
ErikPre 5 years ago
Thank you I'll scour the bight!

ErikPre 5 years ago

Lookahere, this guys also sells tons of other interesting stuff, like Glycine, analytic grade, that should be an interesting developer agent to combine with Vit C....

He also have TEA, for those into alternative developers with extreme shelf life....
ErikPre 4 years ago
Funny how a "name" counts!

Cut from APUG :

"Ordinary table salt contains KI (Potassium Iodide) which is a restrainer. It also decreases sharpness. Sodium Chloride (NaCl or table salt) is not a significant restrainer for films.

Join Date: Apr 2005 Location: Rochester, NY Shooter: Multi Format Posts: 19,535 Images: 65

Funny thing this in view of all the loud noise on this forum over exactly the same remarks - now many of the same people that made a rucus over here, sit completely silent over at APUG.....

Back in the day, when this country was a colony, we knew exactly how to measure those that bent over to the "might of the monarch"!

ErikPre 4 years ago
Chronocrator [deleted] 4 years ago
Wow! What a great discussion about salt!!! Lasts for months. What I know about salt is that it may serve as fixer. That means that it dissolves silver halides. But very slowly...
banivechi 4 years ago
I use iodized salt often: 3 grams for 250 ml developer for B&W Iso 100 and 4.5 grams for B&W Iso 400. No fog at all...
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