Removing surface rust?
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Frapiscide
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Removing surface rust?
What would be the easiest way to remove surface rust from the spyder hole? I ended up having a little bit of surface rust on the top inside portion, closest to the spine.
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hunterseeker5
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Metal polish or a very small buffing wheel (with buffing compound) will serve admirably. For deeper rust and/or pitting you want an acid to eat the ferric oxide leaving behind no trace. Also stay away from the strong phosphoric acid products. Gentle acid and time will do you better than a strong acid for seconds.
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Frapiscide
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OK but that's very old-school. Chelation is the modern way to remove rust with zero eating of the base metal. Such as Evapo-Rust. Any acid will chew away at the base metal, but if you're careful enough you won't notice. Why risk it? Chelate.hunterseeker5 wrote:... you want an acid to eat the ferric oxide ....
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hunterseeker5
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You do realize that evapo rust is both acidic and will eat and etch metal parts over time right? It uses, among other things, dilute phosphoric acid to more slowly remove rust and leave behind that phosphate deposit. :pBolster wrote:OK but that's very old-school. Chelation is the modern way to remove rust with zero eating of the base metal. Such as Evapo-Rust. Any acid will chew away at the base metal, but if you're careful enough you won't notice. Why risk it? Chelate.
No, Evapo Rust isn't an acid, its pH is around 6.1-7 which is in the neutral range. Leaving an item in Evapo Rust for a long time will often give you a darkened "film," which must then be buffed off. But it buffs off easily. If you're doing something like a knife blade, leave it in for an hour at a time and check. The "film" isn't a phosphate coating, it's carbon.
You can make your own evapo-rust with certain chelation chemicals (such as ethylenediaminetetraacetate), but you would definitely not add phosphoric acid! Chelation chems don't play nice with acids. In fact, the guys who brew their own Chelations crank the pH up to 9 (still sort of neutral, but in the base direction).
Chelation is NOT the same as an acid bath. Completely different chemical processes. Acid baths eat both rust and steel, which is why you have to be much more careful with them and accept some destruction of the base metal. Chelation is easy. Even dumb guys like me can do it successfully!!
I've chelated hundreds of tools. The only downsides are (1) expense and (2) sometimes the item gets so clean you lose the patina. And old tools look naked without their patina.
You can make your own evapo-rust with certain chelation chemicals (such as ethylenediaminetetraacetate), but you would definitely not add phosphoric acid! Chelation chems don't play nice with acids. In fact, the guys who brew their own Chelations crank the pH up to 9 (still sort of neutral, but in the base direction).
Chelation is NOT the same as an acid bath. Completely different chemical processes. Acid baths eat both rust and steel, which is why you have to be much more careful with them and accept some destruction of the base metal. Chelation is easy. Even dumb guys like me can do it successfully!!
I've chelated hundreds of tools. The only downsides are (1) expense and (2) sometimes the item gets so clean you lose the patina. And old tools look naked without their patina.
Steel novice who self-identifies as a steel expert. Proud M.N.O.S.D. member 0003. Spydie Steels: 4V, 15V, 20CV, AEB-L, AUS6, Cru-Wear, HAP40, K294, K390, M4, Magnacut, S110V, S30V, S35VN, S45VN, SPY27, SRS13, T15, VG10, XHP, ZWear, ZDP189
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hunterseeker5
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No no no you misunderstand. I'm not saying that Evapo-rust doesn't contain chelation agents, I'm just saying that it is acidic and has etched tools of mine. We're talking along different lines here.
First I should say that I've not used a lot of evapo rust, all of it has been from one batch, so my observations of its actions are based entirely off that single batch. (inductive versus deductive)
The etch that evapo-rust did, most recently on a set of bearings I put in it, most definitely changed the internal dimensions and isn't what I'd call readily buffable.
And hang on I just said it was mildly acidic and you said it was about 6.1...... that is mildly acidic. I feel like you're arguing in a variety of directions here. Lets try to focus in.
Clearly evaporust is acidic, but mildly so. It'll still etch parts, but its not sufficiently acidic for that to be its primary method of action which we know to be chelation.
Somewhere in my digging when I was researching evaporust I dug up a reference to it containing relatively small amounts of phosphoric acid. The black residue it leaves on rust its eaten I just took for granted as being partly composed of phosphate. If you have some reference to demonstrate otherwise please I'd love to see it. **** I'd like to see an ingredients list if you've got one. :P
Anyway the overall point or my original post, which started this argument, is that evapo rust is in fact acidic and can still eat the base metal. Granted it'll do it more slowly than a nasty strong acid bath, but the process still occurs.
Is anything I said unfair?
First I should say that I've not used a lot of evapo rust, all of it has been from one batch, so my observations of its actions are based entirely off that single batch. (inductive versus deductive)
The etch that evapo-rust did, most recently on a set of bearings I put in it, most definitely changed the internal dimensions and isn't what I'd call readily buffable.
And hang on I just said it was mildly acidic and you said it was about 6.1...... that is mildly acidic. I feel like you're arguing in a variety of directions here. Lets try to focus in.
Clearly evaporust is acidic, but mildly so. It'll still etch parts, but its not sufficiently acidic for that to be its primary method of action which we know to be chelation.
Somewhere in my digging when I was researching evaporust I dug up a reference to it containing relatively small amounts of phosphoric acid. The black residue it leaves on rust its eaten I just took for granted as being partly composed of phosphate. If you have some reference to demonstrate otherwise please I'd love to see it. **** I'd like to see an ingredients list if you've got one. :P
Anyway the overall point or my original post, which started this argument, is that evapo rust is in fact acidic and can still eat the base metal. Granted it'll do it more slowly than a nasty strong acid bath, but the process still occurs.
Is anything I said unfair?
No! You're not unfair at all. And you may have better information than I do...several points you make are news to me! Specifically:
ER claims to be in the range of 6.1-7. Seven as you know is dead center, and I have tested drinking water of lower than 6, so it'd be difficult to explain how a pH of 6 would etch metal. As far as metal is concerned, I have no way of explaining how ER would have any acid-type effect; 6.1-7 range is just too mild, or flat neutral, to do any acid etching. There's a difference between "being measurably acidic" and "acid strong enough to remove rust." But, I'm not willing to say that absolutely ZERO of ER's action is due to acidity, because I don't know the mechanism well enough to be that confident. ER is widely known as a non-acid-based rust removal solution, and that leaving a part in for days or weeks doesn't cause base metal to be eaten away as acid would.
Regarding your ability to actually measure etching after ER, that has me downright confused and befuddled. ER is not supposed to etch, that's its whole reason for being! Are you 100% certain you're not viewing the pits and rough surface left behind by the rust that was removed? ER won't do anything about metal that the rust has already eaten away. On several occasions I've ER'd precision tools, and afterwards they looked like crap--the rust was gone but the pits the rust caused, remained.
Just reasoning this through...Imagine you mic a bearing with rust on it. The ID is too small and the OD is too large, due to the rust. You give it an ER bath, the rust is removed, now you mic the bearing and the ID is larger than desired and the OD is smaller. Couldn't the removal of the rust explain the dimension difference? Because the rust has been eating the metal, so once it's gone, you have a part of smaller dimensions. But it's the fault of the rust, not the fault of the ER which removed the rust.
ER's ingredients have been a tightly controlled secret. Some home brews look, smell, and seem to act the same, but ER doesn't publish their proprietary formula for obvious reasons. It's not food, so they're not compelled to share the ingredients. But you've found an ingredients list somewhere that I've not seen? Was it an actual ingredients list sneaked out of the factory, or speculation from people trying to recreate? Believe me I would LOVE to find the formula, and it's news to me that it's out there somewhere. Heck you may be right, I've just never seen the formula reproduced anywhere. Perhaps your google-fu is stronger than mine. The home-brewer chemists generally put base in theirs, rather than acid, but I'm not in the ER factory so...I don't know!
LOL, you and I are probably the only two guys on this whole forum who even care!
ER claims to be in the range of 6.1-7. Seven as you know is dead center, and I have tested drinking water of lower than 6, so it'd be difficult to explain how a pH of 6 would etch metal. As far as metal is concerned, I have no way of explaining how ER would have any acid-type effect; 6.1-7 range is just too mild, or flat neutral, to do any acid etching. There's a difference between "being measurably acidic" and "acid strong enough to remove rust." But, I'm not willing to say that absolutely ZERO of ER's action is due to acidity, because I don't know the mechanism well enough to be that confident. ER is widely known as a non-acid-based rust removal solution, and that leaving a part in for days or weeks doesn't cause base metal to be eaten away as acid would.
Regarding your ability to actually measure etching after ER, that has me downright confused and befuddled. ER is not supposed to etch, that's its whole reason for being! Are you 100% certain you're not viewing the pits and rough surface left behind by the rust that was removed? ER won't do anything about metal that the rust has already eaten away. On several occasions I've ER'd precision tools, and afterwards they looked like crap--the rust was gone but the pits the rust caused, remained.
Just reasoning this through...Imagine you mic a bearing with rust on it. The ID is too small and the OD is too large, due to the rust. You give it an ER bath, the rust is removed, now you mic the bearing and the ID is larger than desired and the OD is smaller. Couldn't the removal of the rust explain the dimension difference? Because the rust has been eating the metal, so once it's gone, you have a part of smaller dimensions. But it's the fault of the rust, not the fault of the ER which removed the rust.
ER's ingredients have been a tightly controlled secret. Some home brews look, smell, and seem to act the same, but ER doesn't publish their proprietary formula for obvious reasons. It's not food, so they're not compelled to share the ingredients. But you've found an ingredients list somewhere that I've not seen? Was it an actual ingredients list sneaked out of the factory, or speculation from people trying to recreate? Believe me I would LOVE to find the formula, and it's news to me that it's out there somewhere. Heck you may be right, I've just never seen the formula reproduced anywhere. Perhaps your google-fu is stronger than mine. The home-brewer chemists generally put base in theirs, rather than acid, but I'm not in the ER factory so...I don't know!
LOL, you and I are probably the only two guys on this whole forum who even care!
Steel novice who self-identifies as a steel expert. Proud M.N.O.S.D. member 0003. Spydie Steels: 4V, 15V, 20CV, AEB-L, AUS6, Cru-Wear, HAP40, K294, K390, M4, Magnacut, S110V, S30V, S35VN, S45VN, SPY27, SRS13, T15, VG10, XHP, ZWear, ZDP189
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Gunslinger
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hunterseeker5
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I'm absolutely positive this is not pitting. Ok full disclosure I did something stupid. Everyone said ER wasn't supposed to etch so when I tossed the bearings in there, with some other parts, I didn't yank them in a hurry they sat in there for a couple days. When I pulled them out the balls, inner race, and outer race on all six bearings had been etched pretty **** evenly EVERYWHERE. Amusingly the less reactive spacers all remained less etched. For the record the gears which were in there came out with an etch as well, although less so than the bearings. For the record corrosion was only on specific parts, namely inside and around the flanges, on the bearings. Most of the bearing surface was completely rust free. Imagine my shock pulling them out......
You're right though that 6 is pretty close to neutral. I haven't done a pH test, but I can smell the acidity if that makes sense to you. I suppose I could try digging up a pH test from somewhere, but already being colored combined with being reactive might skew the results.
I WISH I could come up with the source I found saying it contained small amounts of phosphoric acid. Its possible it was illegitimate, wrong, who knows what. My memory needs a citation stamp to go with everything I've read. God only knows how many arguments I've "lost" simply because I can't remember where I read the information which supported my case.
You're right we may be the only two people on this forum who care, but its caring that makes us problem solvers. Everyone else just sits around complacently waiting for someone to provide a solution or saying "its good enough" while we're constantly annoyed questing for an answer/solution. Satisfaction is overrated, I'd much rather be intrigued.
You're right though that 6 is pretty close to neutral. I haven't done a pH test, but I can smell the acidity if that makes sense to you. I suppose I could try digging up a pH test from somewhere, but already being colored combined with being reactive might skew the results.
I WISH I could come up with the source I found saying it contained small amounts of phosphoric acid. Its possible it was illegitimate, wrong, who knows what. My memory needs a citation stamp to go with everything I've read. God only knows how many arguments I've "lost" simply because I can't remember where I read the information which supported my case.
You're right we may be the only two people on this forum who care, but its caring that makes us problem solvers. Everyone else just sits around complacently waiting for someone to provide a solution or saying "its good enough" while we're constantly annoyed questing for an answer/solution. Satisfaction is overrated, I'd much rather be intrigued.
Well it's a damned shame if ER etched the bearing. Now I'm spooked. Shouldn't matter if you left it in a couple days, but...I don't know what to say! I guess that's a question for the manufacturer. Sure is news to me. And here I thought ER was a carefree way to get rid of rust. I guess you have to watch it too! Well thanks for the head's up, I'll be careful with it. I've been rather sloppy in the past, leaving stuff in for a week at a time. Won't be doing that any more.
Steel novice who self-identifies as a steel expert. Proud M.N.O.S.D. member 0003. Spydie Steels: 4V, 15V, 20CV, AEB-L, AUS6, Cru-Wear, HAP40, K294, K390, M4, Magnacut, S110V, S30V, S35VN, S45VN, SPY27, SRS13, T15, VG10, XHP, ZWear, ZDP189
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hunterseeker5
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Don't get me wrong, its a **** of a lot easier on things than eating rust with straight acid so I still prefer it for use on precision components, but yeah its not carefree.......Bolster wrote:Well it's a damned shame if ER etched the bearing. Now I'm spooked. Shouldn't matter if you left it in a couple days, but...I don't know what to say! I guess that's a question for the manufacturer. Sure is news to me. And here I thought ER was a carefree way to get rid of rust. I guess you have to watch it too! Well thanks for the head's up, I'll be careful with it. I've been rather sloppy in the past, leaving stuff in for a week at a time. Won't be doing that any more.
Either way though on a knife blade an etch is not a big deal, and may even be desirable to some people.