mhutchinson
Plastic
- Joined
- Jul 21, 2017
Good morning folks,
Long-time lurker here, finally ran out of old threads to sift through. Over the months I've spent reading about these things I consistently find good information on this particular forum, so here I am, a young, curious, and enthusiastic-but also inexperienced and probably naive-cowpoke walking through the double-doors of the saloon taking a seat next to the big boys! I'm also sarcastic and not entirely serious about half the time...
Anyway, I'm an amateur woodworker and I enjoy restoring antique tools. I worked in an auto body and mechanical shop throughout high school so I got a rough, general knowledge of some metalworking techniques but nothing substantial. I also took 4 semesters of chemistry in college recently so I understand the basics but, again, nothing substantial.
Over the years I've restored dozens of tools and spent a ridiculous amount of time sanding, grinding, polishing, sandblasting, etc. Part of my quest in tool restoration is to figure out the most effective techniques for various things. The current Holy Grail of endeavors is dealing with that timeless issue that's plagued industry since its birth: rust.
Over the years of exploring methods for rust removal I've tried a number of acids and chemicals, every type of mechanical removal techniques I could find, and a few experiments in converting red rust to the more stable iron oxide. Overall I feel fairly effective in my ability to simply remove rust.
But here's where things get complicated! A lot of old tools have a convenient (sarcasm) combination of rust and patina. The patina is desirable so removing the red rust without losing it is the goal. The old standby is steel wool or some other mild abrasive, and this works well enough with mild rust, but it is tedious and becomes ineffective pretty quickly when dealing with anything other than the mildest surface rust. My current thoughts on how to deal with this:
1) weaken the red rust-though not the patina-enough to make mechanical removal easier
2) convert the red rust (Fe[SUB]2[/SUB]O[SUB]3[/SUB]) to a more stable form like Fe[SUB]3[/SUB]O[SUB]4[/SUB].
3) there are some rust removing chemicals (namely Evaporust) that claim to use "chelating" agents
So far, idea #1 is not working. I've tried mild acids like oxalic and acetic acid-both in fairly dilute solutions-but these are still strong enough to damage the patina. Two variables to play with here:
A) strength of the chemical--perhaps there is something that is just strong enough to damage/weaken red rust but not quite strong enough to eat through patina
B) exposure time--I noticed when using vinegar to remove rust that there is varying results as an item is left in the solution for more or less time. If I timed the ordeal well I could often get rid of all the red rust without the vinegar eating into black rust very much but if I left an object in long enough the vinegar would begin to eat through the black rust that is often underneath the red rust, and I'd end up with a heavily-pitted piece of steel.
Idea #2 is not working yet but I haven't had enough time. My first thought was just to card off as much red rust as possible and then just apply oil over the rest, hoping that the blocking out of oxygen will eventually convert the red rust to black iron oxide. But this might take a while...the other method I've heard about but haven't tried yet is boiling. Still have to read more about that before I'd feel comfortable trying it.
So, that's where I am with my experiments. I'd love to hear suggestions or advice from others who have engaged in this tedious battle over the years. I'm also always looking for good, science-based sources of information on the chemistry beneath all these ideas because without science it's all just old wives' tales. For example, I'm assuming that patina is black iron oxide-Fe[SUB]3[/SUB]O[SUB]4[/SUB]-but I have no way to confirm that. Knowing exactly what it is and what's going on chemically would be helpful.
Any chemists in the house?
Thanks,
Matt
Long-time lurker here, finally ran out of old threads to sift through. Over the months I've spent reading about these things I consistently find good information on this particular forum, so here I am, a young, curious, and enthusiastic-but also inexperienced and probably naive-cowpoke walking through the double-doors of the saloon taking a seat next to the big boys! I'm also sarcastic and not entirely serious about half the time...
Anyway, I'm an amateur woodworker and I enjoy restoring antique tools. I worked in an auto body and mechanical shop throughout high school so I got a rough, general knowledge of some metalworking techniques but nothing substantial. I also took 4 semesters of chemistry in college recently so I understand the basics but, again, nothing substantial.
Over the years I've restored dozens of tools and spent a ridiculous amount of time sanding, grinding, polishing, sandblasting, etc. Part of my quest in tool restoration is to figure out the most effective techniques for various things. The current Holy Grail of endeavors is dealing with that timeless issue that's plagued industry since its birth: rust.
Over the years of exploring methods for rust removal I've tried a number of acids and chemicals, every type of mechanical removal techniques I could find, and a few experiments in converting red rust to the more stable iron oxide. Overall I feel fairly effective in my ability to simply remove rust.
But here's where things get complicated! A lot of old tools have a convenient (sarcasm) combination of rust and patina. The patina is desirable so removing the red rust without losing it is the goal. The old standby is steel wool or some other mild abrasive, and this works well enough with mild rust, but it is tedious and becomes ineffective pretty quickly when dealing with anything other than the mildest surface rust. My current thoughts on how to deal with this:
1) weaken the red rust-though not the patina-enough to make mechanical removal easier
2) convert the red rust (Fe[SUB]2[/SUB]O[SUB]3[/SUB]) to a more stable form like Fe[SUB]3[/SUB]O[SUB]4[/SUB].
3) there are some rust removing chemicals (namely Evaporust) that claim to use "chelating" agents
So far, idea #1 is not working. I've tried mild acids like oxalic and acetic acid-both in fairly dilute solutions-but these are still strong enough to damage the patina. Two variables to play with here:
A) strength of the chemical--perhaps there is something that is just strong enough to damage/weaken red rust but not quite strong enough to eat through patina
B) exposure time--I noticed when using vinegar to remove rust that there is varying results as an item is left in the solution for more or less time. If I timed the ordeal well I could often get rid of all the red rust without the vinegar eating into black rust very much but if I left an object in long enough the vinegar would begin to eat through the black rust that is often underneath the red rust, and I'd end up with a heavily-pitted piece of steel.
Idea #2 is not working yet but I haven't had enough time. My first thought was just to card off as much red rust as possible and then just apply oil over the rest, hoping that the blocking out of oxygen will eventually convert the red rust to black iron oxide. But this might take a while...the other method I've heard about but haven't tried yet is boiling. Still have to read more about that before I'd feel comfortable trying it.
So, that's where I am with my experiments. I'd love to hear suggestions or advice from others who have engaged in this tedious battle over the years. I'm also always looking for good, science-based sources of information on the chemistry beneath all these ideas because without science it's all just old wives' tales. For example, I'm assuming that patina is black iron oxide-Fe[SUB]3[/SUB]O[SUB]4[/SUB]-but I have no way to confirm that. Knowing exactly what it is and what's going on chemically would be helpful.
Any chemists in the house?
Thanks,
Matt