Impact of household salt additives in salt printing?

[pdeeh]

In the UK, almost all "supermarket" salt (i.e. Sodium chloride) contains Sodium ferrocyanide as an anti-caking agent.

Can one expect any impact if one were to use this type of salt for salt printing?

 

[cliveh]

No.

 

[pdeeh]

ta

 

[Anton Lukoszevieze]

I use Maldern sea salt, works a treat.

 

[NedL]

Funny that you should post this right now... in the past couple hours I've been thinking a lot about the salt used for salt prints. The one I just made today was on paper floated on a solution of kosher salt ( with no additives, not even sodium ferrocyanide ) and 0.5% citric acid. I've also made them from Morton's salt which contains calcium silicate, dextrose and potassium iodide; 3 kinds of sea salt, one of which had calcium silicate added as an anticaking agent, a kosher salt that had sodium ferrocyanide added, and saltwater from a salt marsh.

What is interesting is that they all produce slightly different colors. And they all change color a little differently in the first wash and then in the hypo. The one I made today is a sort of slightly yellowish dark brown, which will get richer when it dries.

I still haven't tried seawater from the beach here, or some neat orange alaea salt I brought back from Hawaii. I find it interesting that they are all different, even different brands of kosher salt. If it's pure NaCl, why is that happening? I don't really want to say this, because it would be sort of fun if the best one was some obscure or rare kind, but so far my favorite color is from the first one I tried that happened to be in our cupboard: the Mortons.

 

[Dr Croubie]

If it's pure NaCl, why is that happening?

Well, no matter the source, it's definitely not pure NaCl. Seasalt comes from evaporating seawater. Some other salt comes from mines. I'm not sure what exactly constitutes Kosher salt besides keeping pigs away from it. Some of these might get filtered, some might get re-crystallised a few times to purify them, but either way what you get is certainly not 'pure', there are always going to be impurities. Maybe if you pay a few hundred dollars a gram you can get some titration-grade extra-pure 99.99% stuff, then that should always look the same (although you never know what is the other 0.01%).

Sapphires and Rubies are both the same corundum underneath, even a few parts per thousand of different other elements changes the colour from red to blue to pink or orange or clear...

 

[NedL]

Right, I understand that sea salt has other minerals besides NaCl. For some reason I thought the Mortons or the kosher salts would be closer to pure. But actually the ingredients list only "salt", not which salt!

Sapphires and Rubies are both the same corundum underneath, even a few parts per thousand of different other elements changes the colour from red to blue to pink or orange or clear...

Good point.

 

[Dr Croubie]

hehehe, Dead Link Removed, hehe

 

[NedL]

Now that's the impact of household salt!

 

[pdeeh]

What is interesting is that they all produce slightly different colors.

Well, this is partly what I meant or wondered when I asked the question, although my main concern was that it might kill the process stone dead, although cliveh's admirably succinct reply covers that worry.

Ferrocyanide as well as a few of the things mentioned in your post Ned are photographically active chemicals so it wouldn't surprise me if there were tonal or colour differences as a result.

It's getting towards the wrong time of year here for sun printing, but I might get a few grams of Silver nitrate anyway and hope for a bright September. Mind you I'll need some decent negatives first ... sigh

 

[BrianShaw]

... For some reason I thought the Mortons or the kosher salts would be closer to pure. But actually the ingredients list only "salt", not which salt!

Of the Kosher salts, Morton contains anti-cake (they list it in ingredients) and Diamond Crystal does not.

 

[NedL]

Well, this is partly what I meant or wondered when I asked the question, although my main concern was that it might kill the process stone dead, although cliveh's admirably succinct reply covers that worry.

Ferrocyanide as well as a few of the things mentioned in your post Ned are photographically active chemicals so it wouldn't surprise me if there were tonal or colour differences as a result.

It's getting towards the wrong time of year here for sun printing, but I might get a few grams of Silver nitrate anyway and hope for a bright September. Mind you I'll need some decent negatives first ... sigh

My limited experience agrees with Cliveh: every salt I tried made a print. I've only tried one paper so far: Canson Universal Sketch ( Crob 'Art outside the U.S. ). I had to increase citric acid to 5 or 6% to avoid fogging with this paper. Recently I've been adding 1/2% CA to my salt solution, and I think that has made the final color shift toward brown and away from reddish.

I have only printed paper negatives, you might have some!

 

[pdeeh]

I've got a few ...