May 31, 2011

iodized kitchen salt can replace bromide

Hi folks,

good news. 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. No need to adjust anything else, the pH remains the same. Also much cheaper than peanuts. Bingo.

The blackpoint was misadjusted during scanning by intension to show the perfect even development and not only black borders.

I guess that's a real breakthough for people having problems getting bromide. And the FP4+ and RPX 100 had a very clear base, almost as clear as a transparency film. Semi stand developed like here would have been desatrous if the iodate wouldn't have done the job so excellent.

Since I use about 0.5 g/l pot. bomide compared to 6 g/l iodized salt for medium fast films, and 1 - 1.3 g/l pot. bromide compared to 10 - 12 g/l iodzed salt, the conclusion is to recommend about the tenfold amount of iodized salt compared to pot. bromide as a good starting point. Adjust for your personal needs, more iodate will cause speed loss. So far I have great results with PanF, FP4+, HP5+, Rollei RPX 100, and RPX 400 (see image below) even at 24 °C full stand development. These are all classic emulsions, maybe flat crystal emulsions like Tmax or Delta need an adjustment, maybe less salt? And if you use another salt with another iodate concentration you of course have to recalulate the amounts to.

The salt I used was a very cheap one from the supermarket, 500 g for 29 Eurocent. it contains 0,0025 % potassium iodate. The very small amount in the salt is sufficiant. For the experts: the iodate is probaly reduced by the developer to iodide that's known as a strong restrainer in literature since decades.

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

Cheers - Reinhold


Frank said...

Hello Reinhold,

good news. Which brand of salt have you used?



Anonymous said...

Local variety of salt (sold to protect us from disease due to lack of iodide) is stated to contain KI 0,5mg per 100 gram, that calculates out to 0.0005%, so it looks like I have to use 5 times as much salt to check this??! I'll check the outlets later tonite and have a look see if I can find a better brand.

imagesfrugales said...

The salt I use: iodate: 0,0025 % = 0,0025 g/100g = 2,5 mg/100g

salt with 0,5 mg/100g pot iodide(?) and regarding the difference in molar masses of iodide and iodate you will need about 4 times as much salt. But I suggest you do your own tests.

at Frank: noname salt from the supermarket. Looks loke all the commonly sold iodized salt here in Germany (and probably in Belgium to) has the same concentration od iodate.

kyle said...

I plan to use morton iodized salt ( morton is a leading producer and marketer of salt in the US)

Each 1/4 teaspoon serving of Morton Iodized Salt (1.5 gram weight) contains 130 MICROGRAMS of Potassium Iodide.

I after conversion I ended up with 13mg/150g. So I would need very little salt. But I feel like I messed up somewhere.

imagesfrugales said...

Yep, I calculate 8.7 mg/100g or 0,0087 %. Thats a bit more than 4 times strength of the salt I use, because it contains iodide and not iodate.

Wow, I like the stylish package and the Morton girl. Anybody wants to donate (not available here)? Just kidding, the shipping would exceed many times the effort.

Anonymous said...

Not fully understanding the calculations but I will give this a go! Now just need to wait for payday to buy some salt. Could I in the near future get you to calculate my salt per liter?? I would only be making wild guesses otherwise.
Thank you for the research so far. I have had nothing but success with your recipes

imagesfrugales said...

Hi Woo,

I'm glad you like my recipes. For calculating you may ask in the flickr caffenol group, it's always good to have others check it also and it may be faster. And it's important to know which film you will use.

Payday? Here one pound of iodized salt is about the same as the deposit for a bottle of coke :-D

Cheers - Reinhold

Anonymous said...

This reminds me of a thread I've read in another photo-forum, where salt was discussed as an alternative fixing agent.
Does anybody has experience with it?



imagesfrugales said...

I stated here and at other places many times that trying to fix with salt is pure nonsense. It was done in the early days of photography in the middle of the 19th centuruy with silver-chloride whatsoever plates. Try it and you will see it's rubbish. End of the story.

Barnacle said...


I'm playing with CCM and Adox CHS/50 but getting very fogged negatives at 15mins/20C (this is on 4x5 sheet).

Is it worth adding a little iodised salt to the CCM recipe, or is this better handled with a shorter development time?

These exposed as 100ASA: and

One issue I have with the Adox is low contrast negs in standard developers...



imagesfrugales said...

Hi Neil,

have a look here at some pics by Fiatlux at flickr:

He uses Caffenol-C-L and gets fantastic results.

If you can't get pot. bromide you might try iodized salt.

Another option would be to reduce the soda of C-C-M, 40 g/l instead of 54.

Low contrast in standard devs? Hm .....

Cheers -Reinhold

Maciek Lesniak said...

I will have to give it a go someday (after I'll use up my pottasium bromide stock)

Barnacle said...

Thanks Reinhold,

A new triplet of negatives drying as I write. In this case I reduced the soda to 40g/l (equivalent) in CCM. A first glance suggests that the fog is still present but reduced.

Fiatlux's photos are impressive...

For your UK readers: DP Soda Crystals are available at Waitrose and Tesco supermarkets. It's the decahydrate with a trace of drying agent according to their data sheet though the packet merely claims 'more than 30%' - 50g dried at 140C for 80 minutes reduces to 18g. Adding the decahydrate to water (a) increases the volume of the liquid significantly and (b) *reduces* the temperature as it dissolves - 5-6C this morning.


Barnacle said...

Further update, Reinhold: reduced carbonate, 15 minutes, and CCL using 10g/l of iodised salt (label claims 1150ug/100g *iodine*) stand processing both produce images but with massive fogging.

An example here, along with an R09 development - all on Adox CHS50 -

Any suggestions gratefully received.


imagesfrugales said...

Hi Neil, like stated above:
"The salt I use: iodate: 0,0025 % = 0,0025 g/100g = 2,5 mg/100g"

Your salt contains 1,15 mg/100g, less that 1/2 of my salt.

The staining in Caffenol-C-L looks strange. I only see staining with very low to none Vit-C. But I have no experiance with the Adox film an none with large format. Ask Bo, he's a kind guy.

jojonas said...

this is terrific! holding true to the idea of using household items, making this much more readily avaliable :)

Unknown said...

Caffenol c h with 7 grams of salt/ 500 ml gave me fantastic results! Finally a caffenol recipe that works with tri-x that doesn't require long stand times.
10.5 min @20 degrees. 5 min presoak, aggitation first 30 sec and 5 per minute.
Grain is very fine.
Thanks Reinhold!

imagesfrugales said...

Hi Stephen,

glad to hear of your good results with Tri-X. Thanks a lot for the qualified info.

Best - Reinhold

John Grönvall said...

Excellent news, potassium bromide is almost impossible to get here in Finland!

Due to my medical condition I have 1mg capsules of "pure" Iodine in the cupboard:
I'll try to dissolve one capsule in ½ liter of water and use the corresponding amount and give it a go...

tdddxn said...
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