A Vinegaroon Experiment in Progress

[chuck123wapati]

17 hours ago, Gosut said:

I drive my wife up the wall with my insistence on using measurements when cooking.

"I just add some salt," she might say

""But how much?" I ask. "How long do you let it cook?"

"I don't know. I just as it until it looks right."

That works well for her, but for a simpleton like myself, who only cooks on rare occasions, that's frustrating. I don't have the experience to know what "looks right."

Same thing here. Like soap making, people were making iron liquor long before they understood exactly what was going on, and some of those old timers got mighty good results by eyeballing ingredients. But, like those soap makers of old, others got mixed results. Which is how homemade soap got the reputation of being harsh, because some ended up with excess lye.

With vinegaroon, my question is the amount of free acetic acid, Ideally, an exact combination of iron with acetic acid should yield none, but I doubt that's possible with this kind of set-up. There will be some. If we neutralize it, we introduce sodium bicarbonate to the leather, but simply applying sodium bicarbonate might have bad effects on leather. Yes, I know free acetic and tannic acid would combine with the baking soda, but how much is left in the leather? So many unknowns.

Basically, I want to understand what's going on chemically, and come up with a working recipe for personal use. Some of what I thought would work has already gone out the window, but that in itself teaches something. OTOH, so far there's no orange in the solution itself, so minimizing surface area exposed to air might help. OTOH, would have to do the same thing in a wide mouth container with the steel wool completely submerged in the vinegar to see if it's the smaller surface area or just keeping the steel wool away from oxygen.

 

I too love a good experiment and am looking forward to someone who can for once say it takes x amount of steel wool in y amount of vinegar of a given strength for z amount of days to get a solution of ?% iron That works on leather with ? amount of residual tannic acid. 

How did you set up your experiment? How much steel wool did you use? how much vinegar? By now you should have data that suggests how much the steel wool is reduced daily by the vinegar.  How have your measured that?

What is your method to find out how much iron in solution and tannic acid it takes to achieve Black in an average piece of leather?

what is your method for testing the residual tannic acid in leather?

 

[chuck123wapati]

18 hours ago, Gosut said:

Thanks. I really am ready to dust off my old chemistry text book and start at the front. Have forgotten way too much of this stuff.

This morning it looks like I may be getting significant dissolving of the steel wool. However, that could be shifting due to hydrogen forming on the steel wool and moving it around slightly in the liquid. Will wait and see.

here is an archive of tons o books on leather science.

 this site a good start on finding  what you want just search leather   but this book has info on your speriment you may need. https://archive.org/details/dli.bengal.10689.10394

[chuck123wapati]

18 hours ago, Gosut said:

Thanks. I really am ready to dust off my old chemistry text book and start at the front. Have forgotten way too much of this stuff.

This morning it looks like I may be getting significant dissolving of the steel wool. However, that could be shifting due to hydrogen forming on the steel wool and moving it around slightly in the liquid. Will wait and see.

https://archive.org/details/pub_american-leather-chemists-association-journal

[Gosut]

On 4/13/2023 at 7:12 AM, chuck123wapati said:

 

I too love a good experiment and am looking forward to someone who can for once say it takes x amount of steel wool in y amount of vinegar of a given strength for z amount of days to get a solution of ?% iron That works on leather with ? amount of residual tannic acid. 

How did you set up your experiment? How much steel wool did you use? how much vinegar? By now you should have data that suggests how much the steel wool is reduced daily by the vinegar.  How have your measured that?

What is your method to find out how much iron in solution and tannic acid it takes to achieve Black in an average piece of leather?

what is your method for testing the residual tannic acid in leather?

 

As experiments go, this one has already gone off the rails. It's just steel wool, measured out on a paper plate on a kitchen scale, in a 2 liter plastic soda bottle filled with 5% acidity vinegar. There is no way to  remove the steel wool except by cutting open the bottle. Didn't weigh the bottle before putting in the steel wool and vinegar, so I can't simply pour out the steel wool and weigh it. Even if I did, residual liquid in the steel wool would throw off the results. There's no way other than weighing the steel wool to determine how much dissolved, and the moment I take it out of the bottle and dry it, it's wet steel wool exposed to air, and will oxidize some. I didn't premeasure the vinegar before hand and have topped it off, so even that's out the window. So basically, I have steel wool in a bottle with vinegar and I look at it and go "Yep, there's bubbles on it and the liquid and steel wool shows no orange of rust (or ferric acetate - have learned that's a thing, too), It doesn't even seem to have significantly dissolved the steel wool in a week's time.

That raises the question you brought up: How much ferrous acetate does it take to turn tannic acid black? If most vinegaroon leaves a significant amount of the iron intact, that implies it takes very little. At this point I could remove a tad with a dropper and see what happens to a piece of veg tan scrap, but that's about all. I don't know if I can even measure the tannic acid content in brewed tea to get some idea.

Memories of titration keep coming back, but that means having some sort of indicator for what I want to measure and something that will react to it, not to mention a precise way to measure it.

Am wondering if it would have been better to measure out a small amount of steel wool and vinegar. Doubt a kitchen scale could weigh a single 0000 steel wool strand, but just one with the predicted amount of vinegar might be better for this.

[Gosut]

As to chemistry books, I'm was about to crack open my college textbook, but then found one by Linus Pauling, General Chemistry. So far it strikes me more as high school level, but that's just three chapters in. Don't know yet why he covered calculating the distance of atoms in a solid, but wonder if he will tie it in with electrons and chemical bonds. Pauling's text is from the early 1970s, but figured that for the basic stuff, it should be fine.

[chuck123wapati]

2 hours ago, Gosut said:

As experiments go, this one has already gone off the rails. It's just steel wool, measured out on a paper plate on a kitchen scale, in a 2 liter plastic soda bottle filled with 5% acidity vinegar. There is no way to  remove the steel wool except by cutting open the bottle. Didn't weigh the bottle before putting in the steel wool and vinegar, so I can't simply pour out the steel wool and weigh it. Even if I did, residual liquid in the steel wool would throw off the results. There's no way other than weighing the steel wool to determine how much dissolved, and the moment I take it out of the bottle and dry it, it's wet steel wool exposed to air, and will oxidize some. I didn't premeasure the vinegar before hand and have topped it off, so even that's out the window. So basically, I have steel wool in a bottle with vinegar and I look at it and go "Yep, there's bubbles on it and the liquid and steel wool shows no orange of rust (or ferric acetate - have learned that's a thing, too), It doesn't even seem to have significantly dissolved the steel wool in a week's time.

That raises the question you brought up: How much ferrous acetate does it take to turn tannic acid black? If most vinegaroon leaves a significant amount of the iron intact, that implies it takes very little. At this point I could remove a tad with a dropper and see what happens to a piece of veg tan scrap, but that's about all. I don't know if I can even measure the tannic acid content in brewed tea to get some idea.

Memories of titration keep coming back, but that means having some sort of indicator for what I want to measure and something that will react to it, not to mention a precise way to measure it.

Am wondering if it would have been better to measure out a small amount of steel wool and vinegar. Doubt a kitchen scale could weigh a single 0000 steel wool strand, but just one with the predicted amount of vinegar might be better for this.

So in essence you wont know any more than when you started.

you would need several samples (10 at least in glass jars with lids) all weighed exactly and large enough to get a measurable variance of numbers, each day or time period you designate take one sample weigh it, subtract from the original weight to find loss from evap and gassing off , take out the steel wool dry it and then weigh it. from that you can find out how much iron you have left, you can also find out how much liquid you have left, percentage of steel wool in suspension etc. you can also test the solution ( timed dip test test and total immersion) at the same time on leather that has been tested for PH to see and verify actual visual results.  you could also test different leathers with varying ph levels during your study.

FUN FACT   ==== when drying your steel wool, to find out if it is indeed 100 % dry lay a small scrap of paper on top of it, if the paper curls up the steel wool is still wet and is giving off vapors that affect the paper.

Don't know your age or education level or any of that but speriments like this was about 5th grade level science when i was in school. I also spent a year or so doing testing for the highway department, testing compaction , asphalt, concrete and so on. back then it was all old school basic science no special meters or anything. a lot of grading, washing, drying, weighing and a calculator lol.. not nearly as interesting as the science involved in drilling an oil well. Now that is some sciency stuff there my friend ever see actual oil shale from 10,000 feet down?

[Gosut]

1 hour ago, chuck123wapati said:

So in essence you wont know any more than when you started.

you would need several samples (10 at least in glass jars with lids) all weighed exactly and large enough to get a measurable variance of numbers, each day or time period you designate take one sample weigh it, subtract from the original weight to find loss from evap and gassing off , take out the steel wool dry it and then weigh it. from that you can find out how much iron you have left, you can also find out how much liquid you have left, percentage of steel wool in suspension etc. you can also test the solution ( timed dip test test and total immersion) at the same time on leather that has been tested for PH to see and verify actual visual results.  you could also test different leathers with varying ph levels during your study.

FUN FACT   ==== when drying your steel wool, to find out if it is indeed 100 % dry lay a small scrap of paper on top of it, if the paper curls up the steel wool is still wet and is giving off vapors that affect the paper.

Don't know your age or education level or any of that but speriments like this was about 5th grade level science when i was in school. I also spent a year or so doing testing for the highway department, testing compaction , asphalt, concrete and so on. back then it was all old school basic science no special meters or anything. a lot of grading, washing, drying, weighing and a calculator lol.. not nearly as interesting as the science involved in drilling an oil well. Now that is some sciency stuff there my friend ever see actual oil shale from 10,000 feet down?

It depends on what you mean. As to how much combines with 5% vinegar, that's correct. As to the flaws in the experiment and what should and shouldn't be done, I've learned something. It's interesting to me that I'm not getting orange in the bottle, and the way to see if that's due to the small surface area exposed to air or keeping the steel wool submerged is easy to do.

As to age, I'm in my sixties. As to education, went to college. Still make my living with electricity. Haven't had to use chemistry for that, and it shows.

[Gosut]

Important Update: I have made a huge, wasteful, error.

It first occurred to me that I was stupid in not weighing the steel wool and vinegar mix. If there was no spillage, any decrease in weight would be due to the release of hydrogen. So, noting the decrease in weight over time, would both measure the reaction and allow the calculation of how much ferrous acetate and remaining acetic acid was in the bottle. That’s assuming the decrease was enough to be detected on a kitchen scale. Two liter bottles are unwieldy, though, so I thought of scaling it down to a half liter.

It was then that I discovered I wasn’t just merely stupid, but incredibly stupid. By the chemical equation, it takes 2 moles of acetic acid to react to 1 mole iron. The molar mass of acetic acid is 60.052g, and with 5 grams acetic acid to 1000 ml of water in 5% white vinegar, that’s 5/60.052 moles. That means, with 5% acidity white vinegar, there should be 0.0833 moles acetic acid. Since it takes 2 moles of acetic acid to react with 1 mole of iron, it would take 0.833/2 moles iron = 0.0416 moles iron. The atomic weight of iron is 55.845, so 0.0416 x 55.845 = 2.323g of iron. For 2 liters of 5% acetic acid, that’s 4.646g iron.

And I put 49 grams of iron in that two liters of 5% white vinegar.

No wonder it looks like most of the steel wool is still there; it is. I miscalculated by an order of 10. It would take more than 20 liters of 5% acidity white vinegar to dissolve it all, and that's if the iron reacts to all the acetic acid.

I can forget about measuring the decrease due to producing hydrogen. One liter of 5% acidity white vinegar reacting to iron should produce 0.0416 moles H2. But here I’ve made another error: I remembered gases like hydrogen like to stick together, so there’s H2 and O2, but a mole of hydrogen is still one H. So it should produce 0.0833 moles hydrogen. Multiplying that by the atomic weight of hydrogen and it comes up with a loss of 0.0839g for a liter. For half a liter, that comes to 0.0420g. It would take a very sensitive scale to detect that, and a kitchen scale isn’t going to cut it.

Where does that leave us?

Nowhere. As an experiment, this is at best a learning experience. I can still used the vinegaroon in that 2 liter bottle, just it’ll take maybe at least nine more fillings to use all the iron. That’s a lot.

On the other hand, it seems that it takes only a small amount of iron to make ferrous acetate from vinegar. I still don’t know if it’s possible for the iron to react with all the acetic acid, but given accounts of vinegaroon reacting with baking soda even when there’s surplus iron in the jar, I’d say that’s a no. But remember, this is from the guy who miscalculated the chemical reaction by a factor of 10.

[chuck123wapati]

43 minutes ago, Gosut said:

Important Update: I have made a huge, wasteful, error.

It first occurred to me that I was stupid in not weighing the steel wool and vinegar mix. If there was no spillage, any decrease in weight would be due to the release of hydrogen. So, noting the decrease in weight over time, would both measure the reaction and allow the calculation of how much ferrous acetate and remaining acetic acid was in the bottle. That’s assuming the decrease was enough to be detected on a kitchen scale. Two liter bottles are unwieldy, though, so I thought of scaling it down to a half liter.

It was then that I discovered I wasn’t just merely stupid, but incredibly stupid. By the chemical equation, it takes 2 moles of acetic acid to react to 1 mole iron. The molar mass of acetic acid is 60.052g, and with 5 grams acetic acid to 1000 ml of water in 5% white vinegar, that’s 5/60.052 moles. That means, with 5% acidity white vinegar, there should be 0.0833 moles acetic acid. Since it takes 2 moles of acetic acid to react with 1 mole of iron, it would take 0.833/2 moles iron = 0.0416 moles iron. The atomic weight of iron is 55.845, so 0.0416 x 55.845 = 2.323g of iron. For 2 liters of 5% acetic acid, that’s 4.646g iron.

And I put 49 grams of iron in that two liters of 5% white vinegar.

No wonder it looks like most of the steel wool is still there; it is. I miscalculated by an order of 10. It would take more than 20 liters of 5% acidity white vinegar to dissolve it all, and that's if the iron reacts to all the acetic acid.

I can forget about measuring the decrease due to producing hydrogen. One liter of 5% acidity white vinegar reacting to iron should produce 0.0416 moles H2. But here I’ve made another error: I remembered gases like hydrogen like to stick together, so there’s H2 and O2, but a mole of hydrogen is still one H. So it should produce 0.0833 moles hydrogen. Multiplying that by the atomic weight of hydrogen and it comes up with a loss of 0.0839g for a liter. For half a liter, that comes to 0.0420g. It would take a very sensitive scale to detect that, and a kitchen scale isn’t going to cut it.

Where does that leave us?

Nowhere. As an experiment, this is at best a learning experience. I can still used the vinegaroon in that 2 liter bottle, just it’ll take maybe at least nine more fillings to use all the iron. That’s a lot.

On the other hand, it seems that it takes only a small amount of iron to make ferrous acetate from vinegar. I still don’t know if it’s possible for the iron to react with all the acetic acid, but given accounts of vinegaroon reacting with baking soda even when there’s surplus iron in the jar, I’d say that’s a no. But remember, this is from the guy who miscalculated the chemical reaction by a factor of 10.

YOUR iron will totally rust away long before you would ever need to fill that bottle 9 more times.

 

your math is great no doubt but what about the other 95%  of the liquid in the bottle called water ? the another variable for you to figure out as the water is also acting to dissolve the iron and it is also holding the iron in suspension also. Your making this way to hard, The vinegar is only used to hasten the iron oxidizing away if it mixes that doesn't matter.   its the quantity of iron to the tannic acid that makes the leather black. Vinegar has nothing to do with that process so it doesnt matter about how the iron and vinegar attach to each other because thats not what makes leather black.. The reaction between the iron and the tannic acid in the leather is what makes leather black not vinegar

Here is how i would get the info you want. you would need several samples (10 at least in glass jars with lids) all weighed exactly and large enough to get a measurable variance of numbers, each day or time period you designate take one sample weigh it, subtract from the original weight to find loss from evap and gassing off , take out the steel wool dry it and then weigh it. from that you can find out how much iron you have left, you can also find out how much liquid you have left, percentage of steel wool in suspension etc. you can also test the solution ( timed dip test test and total immersion) at the same time on leather that has been tested for PH to see and verify actual visual results.  you could also test different leathers with varying ph levels during your study.

[chuck123wapati]

16 hours ago, Gosut said:

Important Update: I have made a huge, wasteful, error.

It first occurred to me that I was stupid in not weighing the steel wool and vinegar mix. If there was no spillage, any decrease in weight would be due to the release of hydrogen. So, noting the decrease in weight over time, would both measure the reaction and allow the calculation of how much ferrous acetate and remaining acetic acid was in the bottle. That’s assuming the decrease was enough to be detected on a kitchen scale. Two liter bottles are unwieldy, though, so I thought of scaling it down to a half liter.

It was then that I discovered I wasn’t just merely stupid, but incredibly stupid. By the chemical equation, it takes 2 moles of acetic acid to react to 1 mole iron. The molar mass of acetic acid is 60.052g, and with 5 grams acetic acid to 1000 ml of water in 5% white vinegar, that’s 5/60.052 moles. That means, with 5% acidity white vinegar, there should be 0.0833 moles acetic acid. Since it takes 2 moles of acetic acid to react with 1 mole of iron, it would take 0.833/2 moles iron = 0.0416 moles iron. The atomic weight of iron is 55.845, so 0.0416 x 55.845 = 2.323g of iron. For 2 liters of 5% acetic acid, that’s 4.646g iron.

And I put 49 grams of iron in that two liters of 5% white vinegar.

No wonder it looks like most of the steel wool is still there; it is. I miscalculated by an order of 10. It would take more than 20 liters of 5% acidity white vinegar to dissolve it all, and that's if the iron reacts to all the acetic acid.

I can forget about measuring the decrease due to producing hydrogen. One liter of 5% acidity white vinegar reacting to iron should produce 0.0416 moles H2. But here I’ve made another error: I remembered gases like hydrogen like to stick together, so there’s H2 and O2, but a mole of hydrogen is still one H. So it should produce 0.0833 moles hydrogen. Multiplying that by the atomic weight of hydrogen and it comes up with a loss of 0.0839g for a liter. For half a liter, that comes to 0.0420g. It would take a very sensitive scale to detect that, and a kitchen scale isn’t going to cut it.

Where does that leave us?

Nowhere. As an experiment, this is at best a learning experience. I can still used the vinegaroon in that 2 liter bottle, just it’ll take maybe at least nine more fillings to use all the iron. That’s a lot.

On the other hand, it seems that it takes only a small amount of iron to make ferrous acetate from vinegar. I still don’t know if it’s possible for the iron to react with all the acetic acid, but given accounts of vinegaroon reacting with baking soda even when there’s surplus iron in the jar, I’d say that’s a no. But remember, this is from the guy who miscalculated the chemical reaction by a factor of 10.

here is some info on the process of tanning leather, it has some good numbers and interesting info on tannic acid in leather.https://braintan.com/barktan/1basics.htm