For those who use sodium hydroxide

Don_ih

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One of the annoying features of the stuff I have is that it's in the form of tiny balls which roll in any random direction if they happen to get loose.
 

Saganich

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I use 0.5 g/l of working strength 1+9 D-23. I mix it in directly, stirring and pouring slowly (with eye, skin, and clothing protection) and the amount of exothermic response has been unremarkable.
Interesting. Whats the balpark dev time for a 200 or 400 film?
 

Saganich

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One of the annoying features of the stuff I have is that it's in the form of tiny balls which roll in any random direction if they happen to get loose.

Lol, yea and they jump. I remember the first time I opened a bottle and the little pellets started jumping everywhere.
 

titrisol

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Diluted NaOH (<5%) is relatively easy to make, use cold water or place the beaker in a cold water bath.
Most chemistry classes used to teach to do mix it in an erlenmeyer under running water for cooling

NaOH stores better dry, in a closed bottle as it is very hygroscopic; and it can weld shut glass-on-glass closures
 

chuckroast

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Interesting. Whats the balpark dev time for a 200 or 400 film?

I use this for stand development.

I expose the film at box speed, prewet for 3 min, continuously agitate fo 2 min, agitate again at 31min for 15 seconds and pull at 60 min.

The total time and halfway agitation point can be pulled in somewhat for longer SBR scenes.

The usual warnings apply about getting the film off the bottom of the tank (hang sheet film horizontally and put an inverted funnel under a rollfilm reel) to allow gravity to pull away development byproducts.

This will give you razor sharp images, but - unless you like really pronounced grain - I don't recommend this for 35mm.


9x12 Fomapan 100 print scan example:



35mm Double X print scan example. I don't recall, but the banding on the left is probably due to improper reel suspension :

 
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I use Sodium Hydroxide for Rodinal and some other Phenidone developers. Handling precautions depends on hydroxide form.

I normally use it on flakes/scales and if I pour it without precautions, it releases dust that can be really dangerous, so either handle it careful (which you should) or user a face mask.

I use it on liquid form pretty seldom and you will need and apron if you value your clothes and gloves if you are attached to your hands (which I assume you are). I guess the pellets are the safest form but thats hard to find locally for me.

Not the most dangerous of stuff but requires you to handle with care.
 

chuckroast

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I put a container on a scale and tare the scale.

I then use a spoon to add the required amount to the container, close the Hydroxide back up, and pour the weighed amount slowly into the target liquid. I've never had a dust problem, though I do keep my skin, eye, and breathing protection in place for this.
 
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Agree, slowly is the keyword here.
 

john_s

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I'm planning to use a small amount of sodium hydroxide to adjust the pH of a developer. I buy NaOH locally in screw cap plastic containers, 500g. The plastic is HDPE.

To ensure some accuracy I intend to use as fresh as possible, but I understand that it's so hygroscopic that it would be easy to use too little as it absorbs water from the air so fast. I could make up a stock solution, say 50g/L, and dispense a calculated amount of that, or would a stronger stock keep better (it absorbs carbon dioxide from the air too)?

I recall reading somewhere that there is a concentration of NaOH solution that does not deteriorate, but it was very strong and I don't like the idea of storing it, in case of breakage or leaking. (and it would be difficult to dispense in such a small amount).
 

_T_

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NaOH is sold in many forms, pellets and flakes have been mentioned. Some forms are more prone to producing dust than others, sometimes your particular batch might have more dust in it than others. You don't want the NaOH dust getting into your sinuses if you happen to breathe in a big cloud of it. That's why you should wear a dust mask. If you have a respirator but no dust masks that will work but it will be more hassle.

This is more of an issue the larger the amount of NaOH you're working with. You may find that breathing in the dust is not a great concern.
 
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What About Bob

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For the making of homemade Rodinal from what I am understanding: The sodium or potassium hydroxide is needed to provide the PH necessary to remove the acetyl part of the acetaminophen/paracetamol product thus converting it to p-aminophenol. This is where that recommended 72 hour waiting period comes in, before using the homemade solution.

The other night I was reading about the reverse chemical reaction of p-aminophenol to acetaminophen/paracetamol by fusing in acetic anhydride. I do not totally understand chemistry but I kind of get the idea. I would like to learn more and work with chemistry. Wouldn't be able to afford setting up my own lab nor would I be able to implement one in my own apartment or bathroom. Probably wouldn't be a good idea to do so, lol.
 

koraks

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I understand that it's so hygroscopic that it would be easy to use too little as it absorbs water from the air so fast.

It's not like you open the bottle and *poof...* all the pellets pop up and double in weight. Yes, if you leave the bottle uncapped for a week or more, things will get messy. If you just open the bottle, take some out to weigh it out and use it, there's no concern.

I could make up a stock solution, say 50g/L, and dispense a calculated amount of that, or would a stronger stock keep better (it absorbs carbon dioxide from the air too)?

Yes, a 5% solution will keep well (indefinitely). The same applies here - if you leave that in an open bottle for a year, it'll start to drift. If you open the bottle, pour some out and cap it again, the tiny amount of carbon dioxide that can do to it doesn't do anything at all.

I recall reading somewhere that there is a concentration of NaOH solution that does not deteriorate

Virtually any NaOH solution will not deteriorate. IDK where the myths come from that it would be unstable.

Why not use sodium carbonate or even borax instead?

Depending on the application, target pH and concentration. Some things you simply cannot do with carbonate, let alone borax.
 

lamerko

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If you are going to mix Parodinal, keep in mind that paracetamol/p-aminophenol in the given quantities cannot be dissolved. If you use Paracetamol tablets, the precipitates will not be only from starch and glucose. Therefore, do not filter these particles. I am not a chemist, but probably in a strongly alkaline environment aminophenol has a significantly higher solubility. In my old books, there are precise instructions - the hydroxide must be dissolved separately, because the increase in temperature is not favorable.
And one more thing. The amount of sodium sulfite is consistent with its limit value. It will dissolve, but subsequently SOMETHING will precipitate - whether sulfite or aminophenol, I do not know. This can be relatively easily circumvented if you switch to the potassium formula (KOH + potassium metabisulfite).
 

Don_ih

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It's not like you open the bottle and *poof...* all the pellets pop up and double in weight.

You can tell when moisture has impacted your supply because the pellets start get glossy and stick together. I think it's fairly safe to assume it's fine if they're still running free.
 
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I have a bottle of flaked NaOH. Is about 3 years old. I guess the container is like 1.5-liter size. Probably half of it left. No issues with performance and I store it on my laundry room, which I assume is high on humidity. So yeah, probably a myth, about it being unstable.
 

Saganich

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If the pellets get loose on the counter it takes like 2 or 3 hours before you find the little 'pool' where the pellet was. In the bottle the pellets just seem fine over the last few years, no clumping or anything.
 

john_s

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Since it is such a powerful alkali, the amount I need to balance the pH of a developer is very small, I was concerned about accurate measurement. It is not a myth that it absorbs atmospheric water: The issue is by how much. Also a solution of it will absorb CO2 from the atmosphere so making it up fresh would be important if accuracy were important. I think that some of the readings I've done were more about analytic work where accuracy is more critical, but we're just talking about photography here were a few percent up or down is not going to make much difference. So thank you all for allaying my concerns.
 

koraks

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Also a solution of it will absorb CO2 from the atmosphere

If you run the numbers of how many OH- ions you've got in let's say a 2% NaOH solution, and how much CO2 it'll therefore take to shift the pH by 0.1 or so, you'll probably realize that it's not really a practical concern unless you're going to keep the uncapped beaker of NaOH solution out in the open for weeks or months.
 

Alan Johnson

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I made the potassium version of PaRodinal as this does not have an excess of insoluble sulfite and can be filtered to give a clear solution. However, over time (months) even this slowly deposits crystals. It may be that the clear solution of potassium aminophenolate is supersaturated and some of it comes out in crystal form.
There has to be an excess of hydroxide to get the acetaminophen to aminophenolate reaction to run, I tried it with the calculated stoichiometric amount of hydroxide and nothing happens in 3 days.
 

chuckroast

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I can only speak from my own experience, but ...

  • I typically open tank process film in 2l rubber tanks.
  • At 0.5g/l NaOH, that means I am adding 1g of the stuff to the tank
  • I mix up my D-23 1+9 to get to 2l
  • Then I cal my scale, tare the container
  • Then I open the NaOH bottle and weigh out a gram
  • I cap the container, and slowly add the weighed chemical into the developer tank
  • Total open time of the container is well under a minute
  • Total exposure time of the used chemical to air is only slightly more
  • Never had an issue.
 
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Not as many "H's" to the "p's"! In a less tongue in cheek way neither borates or carbonates are as powerful as hydroxides.
I know, but it's merely a matter of weight. Also, much easier to weigh larger amounts. For D-23, I see no reason to use hydroxides.
 

chuckroast

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I know, but it's merely a matter of weight. Also, much easier to weigh larger amounts. For D-23, I see no reason to use hydroxides.

I haven't done the math, but it would take a whole lot of borax to get there. Carbonate less so.

Weighing and adding a gram of NaOH isn't particularly inconvenient.

If really was a problem, I'd made an NaOH stock solution and use that instead, but I've not found it necessary. Then again, I don't do this a whole lot. if I did, I might rethink weighing it out every time.
 

koraks

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I know, but it's merely a matter of weight.

No, it's not.
Borax is used so much as a buffer because it's so darn stable regardless of concentration.
With carbonate you can get where you'd need to be in a photographic developer as long as you're talking about a working strength solution. For concentrates, you generally need hydroxide.

For D-23, I see no reason to use hydroxides.

That's one specific application, only, and not the one OP asked about in first instance.
 
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