Home |
Search |
Today's Posts |
|
Woodworking (rec.woodworking) Discussion forum covering all aspects of working with wood. All levels of expertise are encouraged to particiapte. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#81
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
Check your inorganic chemistry books under electronegativity. Sodium's
about as good as it gets, iron and copper not in the same league. Of course it helps to have a good acid electrolyte in your cell. Now try cleaning your silver with baking soda in an aluminum pan.... "Dan White" wrote in message et... First of all let me say that my interest in this thread, started by Sandy, was caused by my own questioning of why salt helped clean copper pots with vinegar. |
#82
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
On Wed, 19 May 2004 20:27:09 GMT, "Dan White"
posted: First of all let me say that my interest in this thread, started by Sandy, Nope, I merely interjected my question about the need for salt into an already existing thread. But I see what you mean. was caused by my own questioning of why salt helped clean copper pots with vinegar. Months ago I poured vinegar on a copper pot and it did nothing. Then I sprinkled salt on, and the oxides just wiped away. Wiped away with a cloth? The salt may have been acting as a scourer? Copper is the other side of hydrogen in the electrochemical reactivity table, so perhaps there is some difference here with iron? I figure whatever mechanism was working there is probably not that different from what happens with iron. Except for what I said above. So on with my not-so-scientifically-controlled test: I didn't have any rusted nails, but I did find two old 1.25 lb free weights. These are 4" in diameter with a 1" hole for the barbell to go through. The annular region between this hole and the outer edge of the weight was recessed and could hold maybe a tablespoon worth of liquid, possibly more. The annular region was embossed with the manufacturer's name and the weight. Each weight was rusted moderately and had about the same amount of rust. This means that there is more rust than you could casually remove, but not so much that the weight had deep pits. I poured vinegar into both, and then added an excess of salt to one of them. Within hours, both were effervescing slightly. (They had bubbles collecting on the surface). Note that this was done in contact with air, and with plenty of surface area. After 48 hours I poured the liquid out of each into test tube like containers. What I observe is that the vinegar/salt sample was a light yellowish/orange color, and contained a fair amount of black flecks and little chunks, in addition to some very small black particles. On the other hand, the vinegar/no salt solution was a deep red color, very different from the vinegar/salt sample. It had no flecks or chunks of black material, but did have a fair amount of very fine, small black particles. In both cases, black material built up on the edges of the liquid, and also on some of the submerged surfaces. I cleaned the weights by hand Now this is perhaps the most important step and you have not elaborated. How did you clean these things? The salt crystals can act as a scourer, so if you wiped them with a rag.... and observed that the rust was gone from both, but the vinegar/salt weight looked SLIGHTLY cleaner. I then used a brass brush to clean them up further. After drying them out, it appears that the vinegar/salt weight is a little brighter looking. The vinegar only weight looks darker, as if there is dark material caught up in the fine pits and crevices of the weight. Could be that more of the orange rust had dissolved leaving the black magnetite (Fe3O4), and the salt and vinegar dissolved less of this orange rust leaving it appearing lighter. Both my examples seem minutely more orange (lighter colour) than the non treated parts of the nails. Overall I'd say that there is a definite difference between the two as one liquid was light yellow or orange, and the other was deep red. The vinegar/salt weight also looked a little cleaner, but it is a very slight difference. It could be that these old weights just looked a little different from the start. What caused the red color in one and not the other? Is the iron chloride complex colorless, while FeCl3 is red? I would guess that they are the same colour, containing the same coloured ion Fe+++, but I'm not sure. I'm not even sure that this iron chloride complex exists, as my question as to what happens to all that excess Na+ was never answered. My vinegar-only is definitely effervescing slightly more than the salt and vinegar as seen this morning by swirling the bubbles away and looking again in ten minutes for new bubbles to form. Previously, effervescence appeared roughly similar and quite slight. Sorry for being long-winded. Hope this spurs some ideas. dwhite PS. I might add clean water to each next to see if there is any difference in corrosion rate as postulated by Sandy. My reading suggests that the salt-treated article will rust more, even if left dry. This is the problem, as the salt in the minute pits will attract atmospheric moisture and act as electrolyte in minute electrochemical cells. This will happen more in some alloys than others. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ My experiment was with very rusted nails. The vinegar only solution is brown(orange) and the salt and vinegar is pale yellow. Effervescence is still going ever more strongly (though still quite weak) at 46 hours. There seems to be more black specks floating in the salted version. This may have been due to an original difference in the nails. Both have a few rust particles on the bottom of the tumblers. The nails are imperceptibly different from when I put them in the solutions -- slightly more yellow where the solutions have acted, but still very heavily rusted. I found that salt perhaps inhibits the process slightly, (except, perhaps, as a scourer when the article is wiped with a rag?) I worry about that salt in the rust pits, and so personally would bever use salt on anything of mine that I valued. My conclusion is that this procedure is useless for heavily rusted articles. And salt makes an insignificant difference. A wire brush and/or electrolysis might be a better way to go. Thanks for an interesting exchange, Dan. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Dan: I have some rusted metal soaking for about 36 hours now. I'll stop it Wed afternoon and see what I get. I'll let you know, fwiw. Sandy: I'm now getting a bit of effervescence in mine. Carbonates dissolving, I guess. That's a more promising sign, but 28 hours shows very little cleaning. Not long ago, I stuck a very rusted hose clamp (hydraulically applied) in vinegar in the hope that it would fall apart. What it did do was to make the non-rusted chromed areas nice and shiny. As there was still a lot of metal left, and not all rust as it originally seemed, it required 3000 rpm of an 8" alumina wheel My impression so far is that the salt impedes the derusting process. I have read in places that salt is added to vinegar as a mild abrasive when rubbing a rusted item clean. This is a very different process than the one claimed in this thread. Sandy: That salt and vinegar are useless for derusting rusty tools? Pretty much, I would contend, so far. That Charlie was being a whinging busybody by complaining about our discussion? Yep, see my reponse to Jim. "Jim Wilson" wrote in message k.net... Sandy wrote... Jim Wilson posted: Hyperbole, perhaps? Nope, comparative. Cf dropping a rock on your foot Ok, perhaps more complex than dropping a rock on your foot, but that doesn't say a whole lot, does it? (G) My conclusion so far is that using vinegar to clean off rust is a waste of bloody time It certainly is if you watch it. (G) In the context of whining that our discussion was OT for this forum. Otherwise, what was the aim of his message? That wasn't the context. He started by disagreeing with your assertion that "What we need explaining is why the presence of sodium chloride in the vinegar is advantageous." He noted that "we" non-chemist woodworkers do not need that explained at all. We need only know whether it works, not why. Indeed, even a correct, lucid, and perfectly presented explanation would be of limited utility to the majority, although it might well be interesting to many of us. An inconclusive, jargon-filled technical debate would have to have considerably less utility, wouldn't you agree? Only afterward did he observe that the thread had wandered into OT territory, and even then he did not suggest aborting the thread, but rather that the subject line should have been altered. Don't get me wrong -- personally, I am quite interested in the discussion, and have been following the thread closely, but obviously I do have a penchant for useless academic debate :-). I interjected because I felt your take on Charlie's post was wrong, and that the points he was really trying to make were valid, to wit: 1) most readers of this NG neither need nor want to understand this stuff, and 2) the thread has drifted off topic for this NG. I still want to hear it. Jim |
#83
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
On Wed, 19 May 2004 17:36:16 -0400, "George" george@least posted:
Check your inorganic chemistry books under electronegativity. Sodium's about as good as it gets, iron and copper not in the same league. Although iron and copper straddle hydrogen, which is an important watershed. Very few sodium tools available Of course it helps to have a good acid electrolyte in your cell. That would be acetic acid? H+ is surely what you need to dissolve insoluble carbonates/hydroxides/oxides? (Along with an anion that does not have insoluble salts with the iron) Now try cleaning your silver with baking soda in an aluminum pan.... BBbbbbut the topic was rust "Dan White" wrote in message . net... First of all let me say that my interest in this thread, started by Sandy, was caused by my own questioning of why salt helped clean copper pots with vinegar. |
#84
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
"Sandy" wrote in message
... was caused by my own questioning of why salt helped clean copper pots with vinegar. Months ago I poured vinegar on a copper pot and it did nothing. Then I sprinkled salt on, and the oxides just wiped away. Wiped away with a cloth? The salt may have been acting as a scourer? The salt could be a scouring agent, but I don't think this is the main benefit of salt. If you pour the salt on, you see small regions around each grain where the rust is dissolving, even before you touch the pot with a sponge. Copper is the other side of hydrogen in the electrochemical reactivity table, so perhaps there is some difference here with iron? I figure whatever mechanism was working there is probably not that different from what happens with iron. Except for what I said above. Yes, for sure that could be it. I was hoping not to relearn every electronegativity etc etc. So on with my not-so-scientifically-controlled test: I didn't have any rusted nails, but I did find two old 1.25 lb free weights. These are 4" in diameter with a 1" hole for the barbell to go through. The annular region between this hole and the outer edge of the weight was recessed and could hold maybe a tablespoon worth of liquid, possibly more. The annular region was embossed with the manufacturer's name and the weight. Each weight was rusted moderately and had about the same amount of rust. This means that there is more rust than you could casually remove, but not so much that the weight had deep pits. I poured vinegar into both, and then added an excess of salt to one of them. Within hours, both were effervescing slightly. (They had bubbles collecting on the surface). Note that this was done in contact with air, and with plenty of surface area. After 48 hours I poured the liquid out of each into test tube like containers. What I observe is that the vinegar/salt sample was a light yellowish/orange color, and contained a fair amount of black flecks and little chunks, in addition to some very small black particles. On the other hand, the vinegar/no salt solution was a deep red color, very different from the vinegar/salt sample. It had no flecks or chunks of black material, but did have a fair amount of very fine, small black particles. In both cases, black material built up on the edges of the liquid, and also on some of the submerged surfaces. I cleaned the weights by hand Now this is perhaps the most important step and you have not elaborated. How did you clean these things? The salt crystals can act as a scourer, so if you wiped them with a rag.... I honestly don't think salt scouring had much to do with it. After I dumped out the acid I ran them under water and literally rubbed them with my fingers. It was really more of just brushing the black bits off the metal. I think all the salt had dissolved in the acid after 48 hours, anyway. Now, I next cleaned the weights with a brass brush, so that's where some scouring comes in. Even so, the vinegar/salt weight was cleaner, but I wouldn't say so conclusively. It really could just have been a difference in the two weights from the start. If there were any scouring other than the brass brush, it would probably be more from the bits of Fe2O3 or whatever it is that turns black. and observed that the rust was gone from both, but the vinegar/salt weight looked SLIGHTLY cleaner. I then used a brass brush to clean them up further. After drying them out, it appears that the vinegar/salt weight is a little brighter looking. The vinegar only weight looks darker, as if there is dark material caught up in the fine pits and crevices of the weight. snip ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ My experiment was with very rusted nails. The vinegar only solution is brown(orange) and the salt and vinegar is pale yellow. Effervescence is still going ever more strongly (though still quite weak) at 46 hours. There seems to be more black specks floating in the salted version. This may have been due to an original difference in the nails. Both have a few rust particles on the bottom of the tumblers. The nails are imperceptibly different from when I put them in the solutions -- slightly more yellow where the solutions have acted, but still very heavily rusted. I found that salt perhaps inhibits the process slightly, (except, perhaps, as a scourer when the article is wiped with a rag?) I worry about that salt in the rust pits, and so personally would bever use salt on anything of mine that I valued. My conclusion is that this procedure is useless for heavily rusted articles. And salt makes an insignificant difference. A wire brush and/or electrolysis might be a better way to go. It is interesting, though, to note that in my experiment the vinegar/salt solution was pale orange, while the vinegar only was deep red. I'm interested to see how it ends up in your test. There is *definitely* something different going on in each case, and it would be interesting to know what that is. I wonder if the vinegar only is dissolving more Fe metal, and is somehow inhibited by the salt. Maybe this needs to be done in the absence of air, as the other poster suggested. Maybe the results would be different. Thanks for an interesting exchange, Dan. Ditto. You make a good point about salt corrosion. Good to know. dwhite |
#85
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
Sodium salts are quite soluble versus iron, you know. You've had ion
replacement going on as well as reduction. "Dan White" wrote in message et... Yes, for sure that could be it. I was hoping not to relearn every electronegativity etc etc. It is interesting, though, to note that in my experiment the vinegar/salt solution was pale orange, while the vinegar only was deep red. I'm interested to see how it ends up in your test. There is *definitely* something different going on in each case, and it would be interesting to know what that is. I wonder if the vinegar only is dissolving more Fe metal, and is somehow inhibited by the salt. Maybe this needs to be done in the absence of air, as the other poster suggested. Maybe the results would be different. |
#86
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
Muriatic acid of the sort used for concrete work removes rust
completely and in a fairly short order. I dropped some fine thread rusty bolts in this acid and left it overnight and the threads screwed into the correct size nut with no problem so the metal was not eaten away. The only posssible downside is that the metal is turned to an even light grey, possibly from very light etching |
#87
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
On Thu, 20 May 2004 09:51:42 +0800, Sandy posted:
Final report on the great Salt and Vinegar test Before I hoik it all out and consign the tumblers to the dishwasher, I thought I would describe conditions (About 75 hours, I think) The salt-and-vinegar solution has just about NO colour to it; it has NO effervescence; and a black scum on the surface. The nails are no different from before treatment except that they have gone blacker. There is a an amount of rust flakes on the bottom. The "vinegar-only" still has slight effervescence occurring, and is a strong orange/red colour. The nails are no different except a little more rusty coloured. There is a similar amount of rust flakes on the bottom. As a final twist, I decanted some of the clear orange liquid from the vinegar-only solution and added excess salt. Lo and behold, a black precipitate occurred turning the solution almost chocolate brown and opaque. I will leave this to settle, coz what I'm trying to see is if this purported ferric chloride complex is less orange than the straight ferric ion. So far, half an hour, the red colour seems to be persisting, so unless there is a marked loss of colour, that ferric chloride complex has not been demonstrated. Although the lack of colour in the vinegar-salt test could be because no ferric ions have been formed at all, just black ?magnetite? My conclusion is that although the vinegar and the salt-and-vinegar cause some of the loose rust to fall off the very rusty iron, the treated surface is by no means cleaned. The appearance is not even perceptibly changed. I can't determine if one works better than the other, but from the colours of the solution and the rust and the lesser effervescence, I would conclude the the salt impedes the dissolution process. I will rinse these nails and stick them back out in the rain and see which ones fall apart quicker. and observed that the rust was gone from both, but the vinegar/salt weight looked SLIGHTLY cleaner. I then used a brass brush to clean them up further. After drying them out, it appears that the vinegar/salt weight is a little brighter looking. The vinegar only weight looks darker, as if there is dark material caught up in the fine pits and crevices of the weight. Could be that more of the orange rust had dissolved leaving the black magnetite (Fe3O4), and the salt and vinegar dissolved less of this orange rust leaving it appearing lighter. Both my examples seem minutely more orange (lighter colour) than the non treated parts of the nails. Overall I'd say that there is a definite difference between the two as one liquid was light yellow or orange, and the other was deep red. The vinegar/salt weight also looked a little cleaner, but it is a very slight difference. It could be that these old weights just looked a little different from the start. What caused the red color in one and not the other? Is the iron chloride complex colorless, while FeCl3 is red? I would guess that they are the same colour, containing the same coloured ion Fe+++, but I'm not sure. I'm not even sure that this iron chloride complex exists, as my question as to what happens to all that excess Na+ was never answered. My vinegar-only is definitely effervescing slightly more than the salt and vinegar as seen this morning by swirling the bubbles away and looking again in ten minutes for new bubbles to form. Previously, effervescence appeared roughly similar and quite slight. Sorry for being long-winded. Hope this spurs some ideas. dwhite PS. I might add clean water to each next to see if there is any difference in corrosion rate as postulated by Sandy. My reading suggests that the salt-treated article will rust more, even if left dry. This is the problem, as the salt in the minute pits will attract atmospheric moisture and act as electrolyte in minute electrochemical cells. This will happen more in some alloys than others. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ My experiment was with very rusted nails. The vinegar only solution is brown(orange) and the salt and vinegar is pale yellow. Effervescence is still going ever more strongly (though still quite weak) at 46 hours. There seems to be more black specks floating in the salted version. This may have been due to an original difference in the nails. Both have a few rust particles on the bottom of the tumblers. The nails are imperceptibly different from when I put them in the solutions -- slightly more yellow where the solutions have acted, but still very heavily rusted. I found that salt perhaps inhibits the process slightly, (except, perhaps, as a scourer when the article is wiped with a rag?) I worry about that salt in the rust pits, and so personally would bever use salt on anything of mine that I valued. My conclusion is that this procedure is useless for heavily rusted articles. And salt makes an insignificant difference. A wire brush and/or electrolysis might be a better way to go. Thanks for an interesting exchange, Dan. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Dan: I have some rusted metal soaking for about 36 hours now. I'll stop it Wed afternoon and see what I get. I'll let you know, fwiw. Sandy: I'm now getting a bit of effervescence in mine. Carbonates dissolving, I guess. That's a more promising sign, but 28 hours shows very little cleaning. Not long ago, I stuck a very rusted hose clamp (hydraulically applied) in vinegar in the hope that it would fall apart. What it did do was to make the non-rusted chromed areas nice and shiny. As there was still a lot of metal left, and not all rust as it originally seemed, it required 3000 rpm of an 8" alumina wheel My impression so far is that the salt impedes the derusting process. I have read in places that salt is added to vinegar as a mild abrasive when rubbing a rusted item clean. This is a very different process than the one claimed in this thread. Sandy: That salt and vinegar are useless for derusting rusty tools? Pretty much, I would contend, so far. That Charlie was being a whinging busybody by complaining about our discussion? Yep, see my reponse to Jim. "Jim Wilson" wrote in message k.net... Sandy wrote... Jim Wilson posted: Hyperbole, perhaps? Nope, comparative. Cf dropping a rock on your foot Ok, perhaps more complex than dropping a rock on your foot, but that doesn't say a whole lot, does it? (G) My conclusion so far is that using vinegar to clean off rust is a waste of bloody time It certainly is if you watch it. (G) In the context of whining that our discussion was OT for this forum. Otherwise, what was the aim of his message? That wasn't the context. He started by disagreeing with your assertion that "What we need explaining is why the presence of sodium chloride in the vinegar is advantageous." He noted that "we" non-chemist woodworkers do not need that explained at all. We need only know whether it works, not why. Indeed, even a correct, lucid, and perfectly presented explanation would be of limited utility to the majority, although it might well be interesting to many of us. An inconclusive, jargon-filled technical debate would have to have considerably less utility, wouldn't you agree? Only afterward did he observe that the thread had wandered into OT territory, and even then he did not suggest aborting the thread, but rather that the subject line should have been altered. Don't get me wrong -- personally, I am quite interested in the discussion, and have been following the thread closely, but obviously I do have a penchant for useless academic debate :-). I interjected because I felt your take on Charlie's post was wrong, and that the points he was really trying to make were valid, to wit: 1) most readers of this NG neither need nor want to understand this stuff, and 2) the thread has drifted off topic for this NG. I still want to hear it. Jim |
#88
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
Sandy wrote:
On Thu, 20 May 2004 09:51:42 +0800, Sandy posted: Final report on the great Salt and Vinegar test Before I hoik it all out and consign the tumblers to the dishwasher, I thought I would describe conditions (About 75 hours, I think) (major snippage) Sir: You have WAY too much spare time on your hands. Having said that The effervesence (sp?) may play an important role in rust removal , small bubbles forming in fine nooks and crannies of rust on the piece. As they get bigger they can mechanically, rather than chemically, loosen rust particles - similar to cavitation. However you get the rust off with an aqueous (sp?) solution, after rinsing and hand drying, wipe things down with a paper towel soaked with alcohol. Wipe things down again with a dry towel. The alcohol will grab any water left after the first "wiped dry". charlie b |
#89
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
Sandy wrote:
My conclusion is that although the vinegar and the salt-and-vinegar cause some of the loose rust to fall off the very rusty iron, the treated surface is by no means cleaned. That's a shame, but salt and vinegar is delicious on chips! Ken Muldrew (remove all letters after y in the alphabet) |
#90
|
|||
|
|||
Test Results was Salt and vinegar for rust removal
"Sandy" wrote in message
... My conclusion is that although the vinegar and the salt-and-vinegar cause some of the loose rust to fall off the very rusty iron, the treated surface is by no means cleaned. The appearance is not even perceptibly changed. I can't determine if one works better than the other, but from the colours of the solution and the rust and the lesser effervescence, I would conclude the the salt impedes the dissolution process. Interesting, despite what the others say! Your test about jives with my results, the most notable difference being the nearly clear vinegar/salt solution and the dark red (in my case) vinegar only solution. I would say that the iron did come clean by using the vinegar solutions, but required some brushing to really get all the rust off. I think it came cleaner than it would have had I not used the vinegar, but maybe there are better mechanical ways of doing that, or using a little muriatic acid and being very quick to rinse it off. dwhite |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Rust removal... | Metalworking |