28% acetic acid?

[Ed Pierce]

I'd like to try and make some F6 odorless acid hardening fixer. I can't get glacial acetic acid locally and don't want to pay hazmat shipping charges.

Is Kodak Indicator stop bath the same thing as 28% acetic acid?

[Robert A. Zeichner]

Indicator stop bath has other stuff in it that initially makes the stop bath orange in color, but that turns bluish when close to exhaustion. I've always avoided it. 28% acetic acid is not glacial acetic acid, but rather a dilution of it. You can make 28% acetic acid by diluting glacial acetic acid 3 parts GAA to 8 parts water, but you can't go backwards. If 28% acetic acid is what you really need, you might be able to order that without paying the Hazmat fee. If I'm not mistaken, there is a camera shop in White River Junction that has darkroom chemicals. You might call them to see what they have on the shelf.

[percepts]

28% is one of the magic numbers that comes about because of the manufacturing process of acetic acid. It is not a photographic requirement critical to have it at 28%. I use 25% as its much easier to do quick mental calculations for volumes.

Agfa used to sell 60% acetic acid in 5 litres bottles which could be diluted down with water to 25% to use as stock. They stopped selling it now.

The good news is that all mini labs use aceteic acid in their processors and Fuji sell them 5 litre bottles of 60% acetic acid. So if you can get your local mini lab to get you one of those, then you'll have plenty. Its cheap and you can dilute it down to whatever percentage you like. No indicator in it.

[SamReeves]

Be sure to mix your glacial outside. It's extremely caustic. I usually go 112 oz water with 16 oz glacial. That ought to make a good stop bath with no yeller.

[Marko]

Be sure to mix your glacial outside. It's extremely caustic.

Actually, no, it's exactly the opposite... :D

[tgtaylor]

To use as a photographic stop, Kodak says to mix 2 ozs of acid with 1 gallon of water i.e., 1:64, or one ounce to 64 ozs (half gallon) of water which results in a 1.56% solution. A 28% solution is way too strong.

[percepts]

To use as a photographic stop, Kodak says to mix 2 ozs of acid with 1 gallon of water i.e., 1:64, or one ounce to 64 ozs (half gallon) of water which results in a 1.56% solution. A 28% solution is way too strong.

Methinks 28% is the oft quoted stock solution percentage and not the working solution percentage which is around 1.5% as you say. But you wouldn't mix stock as a 1.5% solution.

[cowanw]

Table vinegar is typically around 5%
Regards
Bill

[Jim Ewins]

Glacial Acetic Acid has a very high freezing point - so keep it at room temp if you wish to dilute.

[tgtaylor]

-----------
Originally Posted by SamReeves
Be sure to mix your glacial outside. It's extremely caustic.

Actually, no, it's exactly the opposite...
__________________
There are only 10 kinds of people - those who understand binary and those who don't.


Actually, no, it's exactly the opposite... :D

WRONG!!! Acetic acid IS caustic. Check the warning notice on the label: "...Causes severe skin and eys burns..."

[tgtaylor]

Methinks 28% is the oft quoted stock solution percentage and not the working solution percentage which is around 1.5% as you say. But you wouldn't mix stock as a 1.5% solution.

Methinks the original question was; "Is Kodak Indicator stop bath the same thing as 28% acetic acid?"

Who's on the door in this place anyway??

[Marko]

WRONG!!! Acetic acid IS caustic. Check the warning notice on the label: "...Causes severe skin and eys burns..."

The warning label does not say it is caustic, it only says that it "causes severe skin and eye burns". And of course, most manufacturers apply strong terms pretty liberally on those labels as a good and cheap way of avoiding lawsuits.

Chemically speaking - and we are talking chemistry here, aren't we? - the term "Caustic" generally refers to strong alkalis only and not acids (another widely misused term) or other types of reactive chemicals. Typical example would be Sodium (or Potassium) Hydroxide.

Acetic acid, on the other hand, is an acid, and a weak acid at that, again purely chemically speaking. It is corrosive, toxic, irritating and all that... but being an acid, caustic it is not.

You probably meant "corrosive", but that's another term altogether.

Then there is the other, figurative meaning of "caustic" and if I wanted to apply that meaning to this case, I would say that your reply was incomplete because even though you used bold, underline, italic and multiple exclamation marks in your reply, you forgot to apply red and blink. Aside from mishandling quotes, of course.

:D

Which brings another point - those green toothy thingies I tend to use in messages like this and the one you were replying to are called "smileys" or "emoticons". They are supposed to convey the emotions through the strictly textual medium such as the discussion board.

This particular one denotes content strong on humor, or at least intended to be. :D

[Marko]

Methinks the original question was; "Is Kodak Indicator stop bath the same thing as 28% acetic acid?"

Who's on the door in this place anyway??

Actually, the original question was about making one's own stop bath out of acetic acid to avoid hazmat shipping charges. Kodak's stop bath was there just for comparison.

No need to worry about guarding the door, we may not have the council of elders or such here ;) but the floors are still clean and if you really want to find out who minds the door, knock hard enough and you'll quickly find out :D.

[Colin Graham]

I'd like to try and make some F6 odorless acid hardening fixer.

Just to refresh everyone's memory. ;)

It is getting harder to find 28%, I was looking for some as an albumen preservative- it's not just for stop bath.

[percepts]

Looking back at some old other forum posts I have, the reason given for 28% stock is that 28% is the strongest dilution obtainable from distillation. That's it. There is no reason to mix 28% solution from glacial acetic acid other than that's what everyone does. Probably because AA did it and gives a formula in his book. It's just a copy cat number that really has no significance today when you can buy 60% and dilute it to whatever you like.

The thing to work out is the working strength solution. Using AA's formula of 45ml of 28% acetic acid plus water to make 1 litre then you can work out that 12.5ml of that 45ml is 100% acetic acid and the other 32.5 is water. So having made it upto 1 litre that means that 12.5 is 1.25% of 1000ml which means AA was using a 1.25% working strength solution of acetic acid.

For myself I still have a bottle and a half of agfa 60%. I dilute some of that down to 25% in a 1 litre bottle and use that for stock.

In some old posts I have on acetic acid, there is also reference to kodak indicator stop being 51% solution but these things change so you should check that before assuming its correct. The formula is published I beleive.
But I still rekon its best (and cheapest) to buy the fuji 5 litre 60% if you can lay your hands on it from a local minilab.

[cowanw]

this page of specs states the indicator stop bath is 85-90 % Acetic acid to make up a 1/63 working strength which if my math is correct yields a 1.56% acetic acid stop bath.
What strength is required for albumin stabilization?

http://www.tedpella.com/msds_html/26956msd.htm
Regards
Bill

[percepts]

this page of specs states the indicator stop bath is 85-90 % Acetic acid to make up a 1/63 working strength which if my math is correct yields a 1.56% acetic acid stop bath.
What strength is required for albumin stabilization?

http://www.tedpella.com/msds_html/26956msd.htm
Regards
Bill

I just had a look at the kodak MSDS pages and there are various kodak stop baths listed. Some indicator baths are listed at 85-90%. Others are listed at much lower strengths. Country of sale may also make a difference.
Don't know about strength for albumin.

[tgtaylor]

The warning label does not say it is caustic, it only says that it "causes severe skin and eye burns". And of course, most manufacturers apply strong terms pretty liberally on those labels as a good and cheap way of avoiding lawsuits.

Chemically speaking - and we are talking chemistry here, aren't we? - the term "Caustic" generally refers to strong alkalis only and not acids (another widely misused term) or other types of reactive chemicals. Typical example would be Sodium (or Potassium) Hydroxide.

Acetic acid, on the other hand, is an acid, and a weak acid at that, again purely chemically speaking. It is corrosive, toxic, irritating and all that... but being an acid, caustic it is not.

You probably meant "corrosive", but that's another term altogether.

Then there is the other, figurative meaning of "caustic" and if I wanted to apply that meaning to this case, I would say that your reply was incomplete because even though you used bold, underline, italic and multiple exclamation marks in your reply, you forgot to apply red and blink. Aside from mishandling quotes, of course.

:D

Which brings another point - those green toothy thingies I tend to use in messages like this and the one you were replying to are called "smileys" or "emoticons". They are supposed to convey the emotions through the strictly textual medium such as the discussion board.

This particular one denotes content strong on humor, or at least intended to be. :D

I don't find any humor in your ignorance.

Glacial Acetic Acid

EMERGENCY OVERVIEW
Appearance: colorless liquid liquid. Flash Point: 39 deg C. Danger! Corrosive. Flammable liquid and vapor. Causes severe digestive and respiratory tract burns. Causes severe eye and skin burns. May be harmful if absorbed through the skin. Acetic acid forms ice-like solid below 62°F (17°C).
Target Organs: Teeth, eyes, skin, mucous membranes.


Potential Health Effects
Eye: Causes severe eye irritation. Contact with liquid or vapor causes severe burns and possible irreversible eye damage.
Skin: Causes skin burns. May be harmful if absorbed through the skin. Contact with the skin may cause blackening and hyperkeratosis of the skin of the hands.
Ingestion: May cause severe and permanent damage to the digestive tract. Causes severe pain, nausea, vomiting, diarrhea, and shock. May cause polyuria, oliguria and anuria. Rapidly absorbed from the gastrointestinal tract.
Inhalation: Effects may be delayed. Causes chemical burns to the respiratory tract. Exposure may lead to bronchitis, pharyngitis, and dental erosion. May be absorbed through the lungs.
Chronic: Chronic exposure to acetic acid may cause erosion of dental enamel, bronchitis, eye irritation, darkening of the skin, and chronic inflammation of the respiratory tract. Acetic acid can cause occupational asthma. One case of a delayed asthmatic response to glacial acetic acid has been reported in a person with bronchial asthma. Skin sensitization to acetic acid is rare, but has occurred.

Definition of Caustic (Merriam Webster)

Main Entry:1caus·tic
Pronunciation:\ˈkȯ-stik\
Function:adjective
: capable of destroying or eating away organic tissue and especially animal tissue by chemical action <silver nitrate and sulfuric acid are caustic agents>

[Marko]

I don't find any humor in your ignorance.

It is not my fault if you are too dim to get it, no need to yell and scream at me. Especially since I wasn't talking to you in the first place.

No need to lecture me about chemistry either, I've got my degree a long time ago.

So go find someone qualified to explain some basic chemical terms to you, such as the difference between acids and alkali, what is strong or weak acid/alkali and what caustic really means.

You can start with Wikipedia, at your level it should be sufficient enough for a while.

[Ed Pierce]

Wow I didn't realize this was such a loaded question.

I found a source for both 28% and glacial on the web with no hazmat charges - digitaltruth.

Thanks everybody

[percepts]

Wow I didn't realize this was such a loaded question.

Ah well, there's always some acidic and caustic responses to most threads. :rolleyes:

[Marko]

Hey Ed,

It isn't charged, it's only... well, caustic at moments. Or, since it is basically acid we're talking about here, dare I say vitriolic? :D

Either way, sorry to see your thread derailed over what was meant to be a small insiders' joke. This forum used to be a lot more relaxed back in the day...

[SamReeves]

Ah well, there's always some acidic and caustic responses to most threads. :rolleyes:

LOL!!! Too true! http://www.freesmileys.org/smileys/smiley-laughing002.gif (http://www.freesmileys.org/smileys.php)

[William McEwen]

I get acetic acid from Photographer's Formulary

http://tinyurl.com/m3o59v

and dilute it to 28 percent myself.

I bought Kodak acetic acid for years and years at camera stores here in Dallas. All stopped carrying it four or five years ago.

[tgtaylor]

To use as a photographic stop, Kodak says to mix 2 ozs of acid with 1 gallon of water i.e., 1:64, or one ounce to 64 ozs (half gallon) of water which results in a 1.54% solution. A 28% solution is way too strong.

You birds don't know what you are doing. Giving newbie's wacko advise on caustic chemicals could end up with one of them seriously injured or even dead.

This thread should serve as a warning to people logging on to this site for advise: Some giving it don't know what they are talking about and there are those that will deliberately steer you wrong. So keep your 'street smarts' with you while here.

Who's on the door in this place anyway?

[William McEwen]

The 28 percent is stock, to be diluted much further when used for photographic applications.

[percepts]

Who's on the door in this place anyway?

You should try hanging out in places that don't need someone on the door. It might give you a different perspective on life. :p

[Marko]

You birds don't know what you are doing. Giving newbie's wacko advise on caustic chemicals could end up with one of them seriously injured or even dead.

This thread should serve as a warning to people logging on to this site for advise: Some giving it don't know what they are talking about and there are those that will deliberately steer you wrong. So keep your 'street smarts' with you while here.

Who's on the door in this place anyway?

Luckily enough, we have "experts" to point all of that out... :rolleyes:

Street-smarts, whatever that meant, can get one only so far. And wherever that point may be, it is NOT far enough for things such as chemistry. It goes without saying that those who choose to engage in chemistry-based processes should educate themselves in a more structured way, starting with correct meaning and usage of specific terminology.

Warning labels are there for those who fail (or are incapable) to do so. They should also refrain from commenting about things they don't quite understand, much less hint at someone else's maliciousness.

Bottom line is this: if you don't understand it, stay away from mixing it yourself, buy commercial products ready-made for the purpose, follow instructions to the letter and don't lecture others about it!

[tgtaylor]

Is Kodak Indicator stop bath the same thing as 28% acetic acid?

No! It's Glacial Acetic Acid with a stop indicator added. To use as a stop bath you dilute 1 Oz with 64 Ozs (half-gallon) of water: 1:64. The capacity of Glacial Acetic Acid, according to Kodak, is 75 rolls of film per gallon of solution.

[tgtaylor]

The 28 percent is stock, to be diluted much further when used for photographic applications.

According to Tim Rudman's The Photographer's Master Printing Course, page 156.
you would "mix 3 parts of the 28% acetic acid solution with 25 parts of water [for a 3% working solution]." 3:25

Lagniappe.

[tgtaylor]

According to Tim Rudman's The Photographer's Master Printing Course, page 156.
you would "mix 3 parts of the 28% acetic acid solution with 25 parts of water [for a 3% working solution]." 3:25

Lagniappe.

After further careful consideration, I am of the opinion the Rudman suggestion of a 3%solution is too strong and, other than perhaps increasing the volume of film/prints processed with a given volume, does not serve a useful purpose.

The strength recommed in the majority of the literature is in the 1% to 2% range and we have seen that the Kodak recommended strength of 1.53% is smack in the middle of these recommendations.

Accordingly, and after careful consideration, I would recommend a 1:16 dulution of 28% acetic acid for a working strength of 1.73%.

Thomas

[Kirk Keyes]

Be sure to mix your glacial outside. It's extremely caustic.

Technically, bases are caustic. Acids are corrosive.

Obviously, Merriam Webster was not a chemist...

[tgtaylor]

Why quibble over the terminology when the results are the same:

What is a caustic chemical? Any strongly corrosive chemical substance, especially one that attacks organic matter.

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Look up corrosive substance in Wiktionary, the free dictionary.

A corrosive substance is one that will destroy or irreversibly damage another substance with which it comes in contact. The main hazards to people include damage to eyes, skin and tissue under the skin, but inhalation or ingestion of a corrosive substance can damage the respiratory and gastrointestinal tracts. Exposure results in chemical burn.

[edit] Terms
The word 'corrosion' is derived from the Latin verb corrode which means 'to gnaw' indicating how these substances seem to 'gnaw' their way through the flesh. Sometimes the word 'caustic' is used as a synonym, but by convention 'caustic' generally refers only to strong bases, particularly alkalis, and not to acids, oxidizers, or other non-alkaline corrosives. The term 'acid' is often used imprecisely for all corrosives.[citation needed]

A low concentration of a corrosive substance is usually an irritant. Corrosion of non-living surfaces such as metals is a distinct process. For example, a water/air electrochemical cell corrodes iron to rust. In the Globally Harmonized System, both rapid corrosion of metals and chemical corrosion of skin qualify for the "corrosive" symbol.

Corrosives are different from poisons in that corrosives are immediately dangerous to the tissues they contact, while poisons may have systemic toxic effects that require time to become evident. Colloquially, corrosives may be called "poisons"; but the concepts are technically distinct. There is nothing, however, which precludes a corrosive from being a poison, that is, there are substances that are both corrosives and poisons.


[edit] Corrosivity
Common corrosives are strong acids and strong bases, or concentrated solutions of certain weak acids and weak bases. Their action on living tissue is based on acid-base catalysis of ester and amide hydrolysis. Both corrosive acids and corrosive bases are able to defat skin by catalyzing the hydrolysis of fats, which are chemically esters. Proteins are chemically amides, which can also be hydrolyzed by acid-base catalysis. Strong acids and bases denature proteins and also hydrate easily. Hydration removes water from the tissue and is significantly exothermic. For example, concentrated sulfuric acid causes thermal burns in addition to chemical burns. Strong oxidizing agents, such as concentrated hydrogen peroxide, can also be corrosive to tissues and other materials, even when the pH is close to neutral. Nitric acid is an example of a strong acid that is also a strong oxidizer, making it significantly more corrosive than one would expect from its pKa alone.

There are also more specific corrosives. Hydrofluoric acid, for example, is initially painless in lower concentrations but easily permeates tissue to selectively attack bone, making it extremely hazardous to work with. It is technically a weak acid, but it produces fluoride ions (the actual corrosive species) after the acid is painlessly absorbed. Although zinc chloride solutions are also regularly acidic (by the Brønsted definition), the zinc cation also specifically attacks hydroxyl groups as a Lewis acid. This explains the ability of zinc chloride solutions to react with cellulose and corrode through paper and silk.


[edit] Common types of corrosive substances

DOT Corrosive LabelCommon corrosive chemicals are classified into:

Acids
Strong acids — the most common are sulfuric acid, nitric acid and hydrochloric acid (H2SO4, HNO3 and HCl, respectively).
Some concentrated weak acids, for example formic acid and acetic acid
Solutions of Lewis acids with specific reactivity, e.g. solutions of zinc chloride
Bases
Caustics or alkalis, such as sodium hydroxide (NaOH) and potassium hydroxide (KOH)
Alkali metals in the metallic form (e.g. elemental sodium), and hydrides of alkali and alkaline earth metals, such as sodium hydride, function as strong bases and hydrate to give caustics
Some concentrated weak bases, such as ammonia when anhydrous or in a concentrated solution
Dehydrating agents such as phosphorus pentoxide, calcium oxide, anhydrous zinc chloride, also elemental alkali metals
Strong oxidizers such as concentrated hydrogen peroxide
Electrophilic halogens: elemental fluorine, chlorine, bromine and iodine, and electrophilic salts such as sodium hypochlorite or N-chloro compounds such as chloramine-T[1]; halide ions are not corrosive
Organic halides and organic acid halides such as acetyl chloride and benzyl chloroformate
Acid anhydrides
Alkylating agents such as dimethyl sulfate
Some organic materials such as phenol ("carbolic acid")

[Marko]

Why quibble over the terminology when the results are the same:

What is a caustic chemical? Any strongly corrosive chemical substance, especially one that attacks organic matter.

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Look up corrosive substance in Wiktionary, the free dictionary.

A corrosive substance is one that will destroy or irreversibly damage another substance with which it comes in contact. The main hazards to people include damage to eyes, skin and tissue under the skin, but inhalation or ingestion of a corrosive substance can damage the respiratory and gastrointestinal tracts. Exposure results in chemical burn.

[edit] Terms
The word 'corrosion' is derived from the Latin verb corrode which means 'to gnaw' indicating how these substances seem to 'gnaw' their way through the flesh. Sometimes the word 'caustic' is used as a synonym, but by convention 'caustic' generally refers only to strong bases, particularly alkalis, and not to acids, oxidizers, or other non-alkaline corrosives. The term 'acid' is often used imprecisely for all corrosives.[citation needed]

[...]

Acids
Strong acids — the most common are sulfuric acid, nitric acid and hydrochloric acid (H2SO4, HNO3 and HCl, respectively).
Some concentrated weak acids, for example formic acid and acetic acid
Solutions of Lewis acids with specific reactivity, e.g. solutions of zinc chloride
Bases
Caustics or alkalis, such as sodium hydroxide (NaOH) and potassium hydroxide (KOH)
Alkali metals in the metallic form (e.g. elemental sodium), and hydrides of alkali and alkaline earth metals, such as sodium hydride, function as strong bases and hydrate to give caustics



Congratulations! I see you discovered Wikipedia and learned the distinction between caustic and acid and even between strong and weak acids! :D

Now on to corrosion: What you quoted is the most common layman's definition, but in the simplest possible technical terms, corrosion is a state of deterioration in metals caused by oxidation through chemical action, most often with water, air or acid.

It's very simple, really:

a) metal
b) water, air or acid (oxygen carrier)
c) oxidation (loss of one or more electrons)

The quibbling over terminology, as you put it, may not matter to you, but it's most immediate function is to precisely and unequivocally convey the meaning of a technical conversation/discussion.

If you choose to lecture other people about something - anything - the first thing you should try to do is get your terminology right, immediately followed by facts.

Especially if some of those people happen to have a formal degree in your chosen topic and you don't.

[tgtaylor]

Marko,

What is a caustic chemical? Any strongly corrosive chemical substance, especially one that attacks organic matter

The above is from the Columbia Encyclopedia. The Meriam Webster quote was from their medical dictionary. It's a generally accepted fact that "any strongly corrosive chemical substance, especially one that attacks organic matter" is a caustic chemical.

Glacial Acetic Acid is a strongly corrosive chemical substance that attackes organic matter.

Therefore Glacial Acetic Acid is a caustic chemical. If you have any doubts, take a whiff and see for yourself (not advised)!

True, the more technical chemical literature does not classify glacial acetic acid as a "caustic" but that is exactly its definition in the English language. This forum is not a proceeding of the Americal Society of Chemists and a reader should not be misled into thinking a caustic substance is somehow not caustic simply because it's not a member of a particular chemical family. Moreover, any real chemist would readily agree that glacial acetic acid is a caustic chemical within the common english definitions cited above.

BTW, it's interesting to note that the respondents attacked for characterizing glacial acetic acid as "caustic" were the only ones to offer a proportionality for obtaining a working solution.

[Marko]

Moreover, any real chemist would readily agree that glacial acetic acid is a caustic chemical within the common english definitions cited above.

BTW, it's interesting to note that the respondents attacked for characterizing glacial acetic acid as "caustic" were the only ones to offer a proportionality for obtaining a working solution.

You had two real chemists directly disagree so far. You attacked and insulted one and lectured the other.

But in the end you may be right, I guess correct terminology really doesn't matter to those who can't calculate simple percentages.

[neil poulsen]

Can we tone it down a bit please?

I think the point is that one needs to be careful with Kodak's concentrated stop bath. I know that I much prefer a stop bath based on citric acid. (Ilford has one.) For example, it doesn't have the odor that Kodak's has.

[tgtaylor]

Can we tone it down a bit please?

I think the point is that one needs to be careful with Kodak's concentrated stop bath.

Amen!!

Mix glacial acetic acid according to the instructions on the package. In the case of 28% acetic acid, mix it 1:16 for a 1.73% working solution. Anything stronger than 2% is not necessary and otherwise is a waste. It's safe as long as you keep your nose out of the bottle (if you must, smell the cap) and mix in a well ventilated location. I mix in the kitchen (2 liters at a time) while hoilding my breath.

[tgtaylor]

As a footnote, I use a 1.53% solution of Glacial Acetic Acid as a stop bath for C-41 and RA-4 print processing in a Jobo processor. For B&W film and prints I use a water stop.

[Kirk Keyes]

I don't find any humor in your ignorance.

Glacial Acetic Acid

EMERGENCY OVERVIEW
Appearance: colorless liquid liquid. Flash Point: 39 deg C. Danger! Corrosive.

What I find amusing that you quoted the above reference and didn't seem to notice that it said "corrosive", and not "caustic".

[Marko]

Talking about ignorance, the following is perhaps the biggest kicker:


Glacial Acetic Acid is a strongly corrosive chemical substance that attackes organic matter.

Therefore Glacial Acetic Acid is a caustic chemical. If you have any doubts, take a whiff and see for yourself (not advised)!


I don't know what is that you are whiffing there, but the logic in all this is truly one of a kind.

A weak acid is strongly corrosive?

It is corrosive because it attacks organic matter?

And it is therefore caustic?

This is, like, awesome, dude!

Gotta post this to some chemical humor boards, nobody'll believe it's been seriously said... :D

[SamReeves]

Open up a bottle of glacial and breathe deeply. Those of you who are nitpicking will quickly find out! ;)

[tgtaylor]

Originally Posted by SamReeves
Be sure to mix your glacial outside. It's extremely caustic.


Technically, bases are caustic. Acids are corrosive.

Obviously, Merriam Webster was not a chemist...

Kirk,

You're confusing a noun with an adjective. In the above post "caustic" was clearly meant as an adjective.

caus⋅tic  /ˈkɔstɪk/ Show Spelled Pronunciation [kaw-stik] Show IPA
Use caustic in a Sentence
–adjective 1. capable of burning, corroding, or destroying living tissue.
2. severely critical or sarcastic: a caustic remark.

–noun 3. a caustic substance.
4. Optics. a. caustic curve.
b. caustic surface.



--------------------------------------------------------------------------------

Origin:
1350–1400; ME < L causticus < Gk kaustikós burning, caustic, equiv. to kaust(ós) burnt (v. adj. of kaíein to burn) + -ikos -ic

Related forms:

caus⋅ti⋅cal⋅ly, caus⋅tic⋅ly, adverb
caus⋅tic⋅i⋅ty  /kɔˈstɪsɪti/ Show Spelled Pronunciation [kaw-stis-i-tee] Show IPA , caus⋅tic⋅ness, noun


Synonyms:
2. biting, mordant, bitter, scathing, acid.

[Kirk Keyes]

Kirk,
You're confusing a noun with an adjective. In the above post "caustic" was clearly meant as an adjective.

Actually, you and Sam are confusing caustic with corrosive.

To quote Hawley's Chemical Dictionary, 14th Ed. -


Caustic. (1) Unqualified, this term usually refers to caustic soda (NaOH). (2) As an adjective, it refers to any compound chemically similar to NaOH, e.g, caustic alcohol (C2H5ONa). (3) Any strong alkaline material that has a corrosive or irritating effect on living tissue.

Corrosive material. Any solid, liquid, or gaseous substance that attacks building materials or metals or that burns, irritates, or destructively attacks organic tissues, most notably the skin and, when taken internally, the lungs and stomach. Among the more widely used chemicals that have corrosive properties are the following:

acetic acid, glacial
acetic anhydride
bromine
chlorine
fluorine
hydrochloric acid
hydrofluoric acid
nitric acid
potassium hydroxide
sodium hydroxide
sulfuric acid

So for a material to be caustic, it has to be similar to sodium hydroxide (NaOH), regardless of its use as a noun or an adjective. Acetic acid, is not similar to sodium hydroxide in this respect, as acetic acid is acidic and sodium hydroxide is basic.

Note that acetic acid is the first item listed as corrosive by Hawley - thanks to the list being presented in alphabetical order.

So the interesting thing to learn here is that sodium hydroxide is both corrosive and caustic, while acetic acid corrosive and not caustic.

[Gem Singer]

Don't we humans use vinegar (acetic acid) in many of our food products?

Seems to me that vinegar would be a dangerous substance to ingest if it was corrosive and attacked organic matter.

Vinegar and oil salad dressing, ketchup, and pickles (to name a few) would be toxic.

[Alan Rabe]

Yes vinager has acteic acid in it. It is pretty close to the same dilution as the working solution used in photgraphy.

[Kirk Keyes]

To quote Paracelsus, "All things are poison and nothing is without poison, only the dose permits something not to be poisonous."

[Marko]

Indeed.

Our stomachs produce and contain hydrochloric acid, one of the strongest. Most of us get to feel it at one point or the other as heartburn. It doesn't cause (serious) harm because it is diluted to less than 1%.

To put things in perspective, acetic acid is technically classified as a weak acid and hydrochloric acid as a strong one.

[tgtaylor]

Don't we humans use vinegar (acetic acid) in many of our food products?

Seems to me that vinegar would be a dangerous substance to ingest if it was corrosive and attacked organic matter.

Vinegar and oil salad dressing, ketchup, and pickles (to name a few) would be toxic.

Gem,

I believe that Glacial was first distilled from vinegar. Where vinegar is roughly 2% glacial, Glacial Acetic Acid is 99.5 to 100% pure. From Glacial's Material Safty Data Sheet:

Emergency Overview
--------------------------
POISON! DANGER! CORROSIVE. LIQUID AND MIST CAUSE SEVERE BURNS TO ALL BODY TISSUE. MAY BE FATAL IF SWALLOWED. HARMFUL IF INHALED. INHALATION MAY CAUSE LUNG AND TOOTH DAMAGE. FLAMMABLE LIQUID AND VAPOR.

SAF-T-DATA(tm) Ratings (Provided here for your convenience)
-----------------------------------------------------------------------------------------------------------
Health Rating: 3 - Severe (Poison)
Flammability Rating: 2 - Moderate
Reactivity Rating: 2 - Moderate
Contact Rating: 4 - Extreme (Corrosive)
Lab Protective Equip: GOGGLES & SHIELD; LAB COAT & APRON; VENT HOOD; PROPER GLOVES; CLASS B EXTINGUISHER
Storage Color Code: Red (Flammable)

[tgtaylor]

Actually, you and Sam are confusing caustic with corrosive.

So the interesting thing to learn here is that sodium hydroxide is both corrosive and caustic, while acetic acid corrosive and not caustic.

Another interesting and the main thing to learn here is that the adjective "caustic" accurately describes the action of NaOH and Glacial Acetic Acid on human tissue.

Here's yet another definition of caustic - this time from the American Heritage Dictionary, 2d College Edition:

caustic, adj. Capable of burning, corroding, disolving, or otherwise eating away by chemical action.

Note also the derivation of the word caustic: From the Greek kaustikos < kaiein, to burn.

Nowhere in the english language is caustic limited to bases or alkali. In fact an alkali is defined in Hawleys Condensed Chemical Dicionary (11th Edition) as:

ANY (emphasis added) substance which in water solution is bitter, more or less irritating or caustic (emphasis added) to the skin and mucus membranes; Sounds like NaOH and Glacial to me.

[Kirk Keyes]

In fact an alkali is defined in Hawleys Condensed Chemical Dicionary (11th Edition) as:

ANY (emphasis added) substance which in water solution is bitter, more or less irritating or caustic (emphasis added) to the skin and mucus membranes; Sounds like NaOH and Glacial to me.

If you wish to expand this to alkalis, please note:


any substance which in water solution is bitter, more or less irritating or caustic to the skin and mucus membranes

Note that is says caustic when talking about an alkali. Hawley's is talking about a sodium hydroxide related compound. Caustic does apply to alkalis, but not to acetic acid, as acetic acid is not an alkali.

[Marko]

Nowhere in the english language is caustic limited to bases or alkali. In fact an alkali is defined in Hawleys Condensed Chemical Dicionary (11th Edition) as:

ANY (emphasis added) substance which in water solution is bitter, more or less irritating or caustic (emphasis added) to the skin and mucus membranes; Sounds like NaOH and Glacial to me.

Dude! Do you even read what you quote yourself???

Look at the bolded part of what you wrote yourself.

[...] an alkali is defined [...] as

Now, which part of Glacial Acetic Acid don't you understand?

[tgtaylor]

If you wish to expand this to alkalis, please note:


any substance which in water solution is bitter, more or less irritating or caustic to the skin and mucus membranes

Note that is says caustic when talking about an alkali. Hawley's is talking about a sodium hydroxide related compound. Caustic does apply to alkalis, but not to acetic acid, as acetic acid is not an alkali.

Well, you're a fan of Hawley's which defines the noun substance as "Any chemical element or compound." Now, and this is where you and Marko have trouble, apply the adjective "any" to the noun substance. What do you get?

Also, note the conjunction "or" in "...irritating or caustic..."

Again, what do you come up with?

FWIW, Hawley's
is not recognized as an authority on the english language.

[aduncanson]

... In fact an alkali is defined in Hawleys Condensed Chemical Dicionary (11th Edition) as:

ANY (emphasis added) substance which in water solution is bitter, more or less irritating or caustic (emphasis added) to the skin and mucus membranes; Sounds like NaOH and Glacial to me.

I do not imagine that you are trying to argue that acetic acid is an alkali, although that seems to the the upshot of your statement "Sounds like NaOH and Glacial to me."

However, there is yet another technical definition of a familiar term that you need to consider. No matter how unpleasant tasting, concentrated acetic acid is not bitter. Rather it is sour, and so would not satisfy the definition you quoted. (Although the consequence of that for the larger argument, I cannot fathom.)

Please, please do not invite me to taste my stop bath concentrate to convince me that acetic acid is indeed bitter.

[Kirk Keyes]

FWIW, Hawley's
is not recognized as an authority on the english language.

Hawley's is a recognized authority on the usage of the english language as it applies to chemistry. You are discussing words as they relate to the subject of chemistry. I assumed that you would be interested in how the word "caustic" is used in the field of chemistry.

If you are interested in using the word "caustic" in the literary sense, feel free to use it as you wish.

If you are interested in discussing the chemical properties of a substance, any substance, then please try to use the terms correctly.

[Kirk Keyes]

Well, you're a fan of Hawley's which defines the noun substance as "Any chemical element or compound." Now, and this is where you and Marko have trouble, apply the adjective "any" to the noun substance. What do you get?

Also, note the conjunction "or" in "...irritating or caustic..."

Again, what do you come up with?


I come up with alkalis are caustic.

I agree. The problem is that that acetic acid is not an alkali. It is not an alkali for several reasons.

[tgtaylor]

I come up with alkalis are caustic.

I agree. The problem is that that acetic acid is not an alkali. It is not an alkali for several reasons.

Is Glacial Acetic Acid "capable of burning, corroding, or destroying living tissue?"

[Kirk Keyes]

It is, and that is what makes it corrosive.

To make is caustic, it must be both corrosive AND a stong alkaline material, and it is not alkaline.

[Marko]

Careful Kirk, before you know it, you'll get an Energizer Bunny thrown at you... :D

[iamjanco]

Why does a caustic feeling seem to overcome me when I read this thread...

[Kirk Keyes]

The Energizer Bunny has alkaline batteries, making the contents of them caustic. And corrosive.

[Jim Rice]

Not wishing to interfere with the p****** contest here, but I am curious. Why do folks avoid Kodak's indicator stop? It's the only thing available off the shelf here and there's a finite amount of energy I'm willing to devote to stop bath unless I'm missing something.

[Kirk Keyes]

I use Kodak Indicator Stop. I also have a bottle of 28% acetic. I use them for making a pH buffered stop bath along with sodium acetate, as described in the Film Developing Cookbook by Anchell and Troop. The advantage of a pH buffered stop bath is it can have high acidity but not a low pH. This allows it to stop development very quickly, it lasts a long time, and it reduces the amount of gelatin swell while the film is in the stop bath.

For papers, I got tired of the smell of acetic acid in the open trays, so I use citric acid stop.

[tgtaylor]

It's not necessary to use an acid stop bath for film. In fact, a water stop is probably recommended more often than a acid stop. Agitate for 30 seconds before discarding and adding the fix is the way I learned.

I was using an acid stop for B&W paper but after switching to Photographer's Formulary TR-4 fix, I now use a water stop for B&W paper as well with frequest changes of water. Note, however, that according to the label a stop with TF-4 is not necessary: You can go from the developer directly to the fix.

I now use an acid stop only for C-41 film and RA-4 paper processing in a Jobo processor.

[Kirk Keyes]

There's a lot of things that aren't "necessary", but are still useful.

I prefer to use stop baths as they do have benefits, like stopping development, whereas water "stop" just slows down development via dilution...

But to each his own.

[percepts]

Not wishing to interfere with the p****** contest here, but I am curious. Why do folks avoid Kodak's indicator stop? It's the only thing available off the shelf here and there's a finite amount of energy I'm willing to devote to stop bath unless I'm missing something.

acetic acid is dirt cheap if bought in the correct form. Don't get paranoid about indicator stop not being any good. It will work fine but at a stupid price.

[tgtaylor]

I prefer to use stop baths as they do have benefits, like stopping development, whereas water "stop" just slows down development via dilution...

But to each his own.

True. That's why I use a stop bath when processing color with the Jobo. For example, an 8x10 print in the Jobo requires just 61ml of chemistry - too small an amount to not use an acid stop. Before switching to the Photographer's Formulary Fix I used Kodak Indicator stop bath for B&W paper printing but have always used water for film. But now that it has been brought up and since I have an empty and unused 1/2 gallon container, I'll mix up a stop bath of 1.53% Glacial for film and see if there is any noticable difference.