My 12 gauge single barrel got rusted, due to the rust all smoothness and finishing gone for ever.Gunsmith here applies different methods to restore the original Bluing but still its not good. I learned a lot from this video, please help me further for the nice results.Thanks Steve for the superb upload.
Thanks for you comment! if you want to try something else, you might want to try cold bluing as well, visually it gives similar (or even better) results without potential heat distortion.
I think this is blacking, an old blacksmith trick. It does help protect the metal but it's quite superficial and not very durable. Bluing forms layers of magnitute (IIRC) which you impregnate with oil. Totally different from what you demonstrated.
Understand that no bluing method, including the very hazardous industrial methods, is terribly durable. They are relative to each other as to durability. The only reason they’re used is that painting those parts isn’t practical for various reasons, cosmetics being one.
@@ShadowLancer128 hot bluing isn’t that durable, it does rust if moist. And please don’t try to play a physics card. It has nothing to do with that, it’s chemistry. I had four years of physics and six years of chemistry, so don’t go there.
This is NOT bluing. Heating steel till it turns blue ruins the heat treatment and hardness of the steel. Proper steel bluing is done using a solution of potassium nitrate, sodium hydroxide, and boiling water.
@@LBCAndrew Depending on the desired specification, the state of temper/hardness does not always matter. Nevertheless it is important to have some knowledge of how the steel might be affected.
A thin layer of oil will be contained within the surface after heating and oxidizing the part which provides some protection. I am planning on doing a video on testing cold blue vs this proces regarding rust protection.
My airgun lost its bluing in one spot, could i heat that part and put a few drops of oil on just it? Also could I put gun oil instead of vegetable oil? Thanks!
In that situation I would recommend using cold blue. I think it will work better for small spots, additionally you don't have to heat up the part at all.
For hot bluing the ideal temperature is 250-300C (480-570 F) I am afraid that it will mess with the temper but I am not an expert on that to be honest.
I would leave it alone. If it's a high carbon steel blade which ot sounds like, and not stainless well you could ruin the heat treatment of the blade. There is a way to blue off blades but it's usually done during manufacturing. Certain foods will interact with the steel. I imagine it's a larger knife too, so allot of heat would needed and needs to be uniform. So if the handle is timber it will burn. Show it to a knife smith and see what they think could be a option for you? Good luck.
Doing this would ruin the hardening and tempering of the knife. Any temperature over 450'f will make the steel soft and no longer hold a decent edge. The only way to fix that is to heat the knife till it's no longer magnetic, around 1450'f then quench in either water or oil (depending on the type of steel) to make the steel hard again. Then Bake in an oven at 400-450;f for 1-2 hours to make the hard brittle knife into a "tough" steel.
Actually no: The straw color appears first, turning to gold, then purple, then blue and finally black. The blueing in the video has pushed the color past the blue region into the black. He should have heated the part more slowly, not using a torch but rather a bed of hot beads of metal shavings (check Clickspring's excellent video on just this procedure). This would give a more even color and would allow for removing the part when truly blue, as the metal goes through the various colors in well under a minute ( a few seconds with a torch as strong as that of the video).
I am not sure which type of oil is best for bluing, a lot of people recommend light oils like vegetable oil or hydraulic oil, some even suggest water. Personally I have gotten really good results with vegetable oil.
It kind of depends on the result you are looking for. When you heat up steel it will start to change color, dipping it in oil at the right time will preserve that color. I like to heat it up to around 280 C (540 F) www.quora.com/What-is-the-temperature-of-steel-when-it-is-heated-to-a-blue-color
The temperature at which steel starts to blue is a lot lower than the hardening temperature, when the molucule structure is affected by heating and quenching. There should be no difference in hardness.
@@EngineerSteve Nonsense. Any temperature over 400'f begins to ruin the hardness of steel. When i temper the knives i make, i heat till 450'f which makes the steel turn a straw color, and that is what makes super hard brittle steel into a tough usable steel. The actual hardening process prior to tempering requires temps of over 1450'f though.
I think polymerization really creates a layer by heating up oil/grease, while bluing steel is more of an oxidation proces. But then again I'm not a specialist in that specific field so I could be wrong.
@@EngineerSteve i think your right but im not sure if when you dip the part in the oil it's polymerizing the oil onto the steel or causing some sort of reaction for it to oxide a certain way
@@jlh357 My (limited) understanding is that the steel oxidizes when you heat it up, thus discoloring the steel to a blue color (the color depends on temp.) The oil then cools down the steel, leaving the oxidized color. The chemical details of the rust protection by oil is not known to me, but I will look into it.
I have yet to try this process on stainless steel, of course the purpose of bluing is rust prevention, which is not that much of an concern on stainless. If you are aiming for discoloration you can surely change the color of stainless by just heating it.
Not necessarily, I chose for vegetable oil because it is cheap and accessible. It will work with other oil as well, I am unsure whether the results will be different or not.
@@EngineerSteve That's interesting. I'd be worried about doing so with firearms parts as that may ruin the temper and present a safety issue.. but this is cool nonetheless.
@@MausTanker I would not advise doing it on vital gun parts for the concern that you mentioned. Cold bluing seems more suitable for that purpose, I would imagine.
Hot bluing basically destroys your part, since it´s a head treatment technique. It´s also the worst method to prevent corrosion in steel. It´s only a very very thin layer which needs constant oiling. Do zinc plating or painting instead if you want to preserve your parts structure not cause warpage and get better corrosion protection.
The temperature to which the part is heated, barely changes the structural strength of the part. The annealing temperature for steel is around 815 C (1500 F), where as hot bluing happens closer to 290 C (550 F). I hope this clears thing up, rust protecting properties are not that good indeed but hot bluing has its use cases. Have a nice day.
@@EngineerSteve Hardening temp is a range depending on material of about 800°C-900°C However, temperatures as low as 250°C have an influence on the parts structure. That´s why parts have to be annealed in an oven after heat treatment which makes them hard and brittle, to simply gain their ductility back. As you can see hot bluing is in a range where the material structure is influenced, not as much as hardening does but still sufficient enough to change the part properties for certain applications. Martensitic structures within the steel already change at 150°C.
@@EngineerSteve Exactl! Hot bluing parts should be a good idea right after you forge them, since you have to heat treat them anyway, so you can just dip em into some oil and later on anneal the part. Honestly this is the biggest disadvantage of steel which I hate, it´s super prone to corrosion unless you use Chrome in the alloy.
There seem to be a lot of contradicting opinions on wheter this is hot bluing or not. All I know is that this process is also known to people as hot bluing but I'm not expert.
This process is commonly referred to as'hot bluing' my best guess is that the metal oxidizes to a blue colour (by means of heating it) before being cooled down in oil, hence the name
I don't really agree with that, you need to heat up the part to a certain temperature, to which the color is a good indication. My torch is not that powerfull so it took a while, that's why it looks like tempering.
This is not hot bluing; hot blueing uses an alkali solution at elevated temperatures to get the reaction. What you are doing here is a type of bluing, but it's closer to seasoning a cast iron skillet than actual "hot bluing". From Wikipedia: The "hot" process is an alkali salt solution using potassium nitrite or sodium nitrate and sodium hydroxide, referred to as "traditional caustic black", that is typically done at an elevated temperature, 135 to 155 °C (275 to 311 °F). This method was adopted by larger firearm companies for large scale, more economical bluing. It does provide good rust resistance, which is improved with oil. en.wikipedia.org/wiki/Bluing_(steel)
My 12 gauge single barrel got rusted, due to the rust all smoothness and finishing gone for ever.Gunsmith here applies different methods to restore the original Bluing but still its not good.
I learned a lot from this video, please help me further for the nice results.Thanks Steve for the superb upload.
Thanks for you comment! if you want to try something else, you might want to try cold bluing as well, visually it gives similar (or even better) results without potential heat distortion.
Thanks
I think this is blacking, an old blacksmith trick. It does help protect the metal but it's quite superficial and not very durable. Bluing forms layers of magnitute (IIRC) which you impregnate with oil. Totally different from what you demonstrated.
Understand that no bluing method, including the very hazardous industrial methods, is terribly durable. They are relative to each other as to durability. The only reason they’re used is that painting those parts isn’t practical for various reasons, cosmetics being one.
@@melgross wait so painting is MORE durable, NOT less, than hot bluing?
God, I need to go back and take a physics class.
@@ShadowLancer128 hot bluing isn’t that durable, it does rust if moist. And please don’t try to play a physics card. It has nothing to do with that, it’s chemistry. I had four years of physics and six years of chemistry, so don’t go there.
Thank you very much.
Thanks for your comment!
It IS bluing and defnitely more durable than any of the cold bluing solutions. Nice video Steve.
Thanks for your comment! I am planning to compare the durability of cold and hot bluing to see what the difference is.
This is NOT bluing. Heating steel till it turns blue ruins the heat treatment and hardness of the steel. Proper steel bluing is done using a solution of potassium nitrate, sodium hydroxide, and boiling water.
@@LBCAndrew Depending on the desired specification, the state of temper/hardness does not always matter. Nevertheless it is important to have some knowledge of how the steel might be affected.
im digging the content. gentle voice over works well too. piano music should be upbeat
Thanks for your comment! appreciate it
Great channel. I learn a lot.
Thanks !
Does this protect the metal from rust aswell or is it just decorative?
A thin layer of oil will be contained within the surface after heating and oxidizing the part which provides some protection. I am planning on doing a video on testing cold blue vs this proces regarding rust protection.
My airgun lost its bluing in one spot, could i heat that part and put a few drops of oil on just it? Also could I put gun oil instead of vegetable oil? Thanks!
In that situation I would recommend using cold blue. I think it will work better for small spots, additionally you don't have to heat up the part at all.
Hi I just want to ask if is it okay to hot blue a butcher knife to avoid rust? Will it affect the steel or the food it slices?
For hot bluing the ideal temperature is 250-300C (480-570 F) I am afraid that it will mess with the temper but I am not an expert on that to be honest.
I would leave it alone. If it's a high carbon steel blade which ot sounds like, and not stainless well you could ruin the heat treatment of the blade.
There is a way to blue off blades but it's usually done during manufacturing.
Certain foods will interact with the steel.
I imagine it's a larger knife too, so allot of heat would needed and needs to be uniform.
So if the handle is timber it will burn.
Show it to a knife smith and see what they think could be a option for you?
Good luck.
Doing this would ruin the hardening and tempering of the knife. Any temperature over 450'f will make the steel soft and no longer hold a decent edge. The only way to fix that is to heat the knife till it's no longer magnetic, around 1450'f then quench in either water or oil (depending on the type of steel) to make the steel hard again. Then Bake in an oven at 400-450;f for 1-2 hours to make the hard brittle knife into a "tough" steel.
@@LBCAndrew Well said, your knowledge on this topic surpases mine.
Basically when you get the part to around 570 degrees is when the darkest blue shows. Any hotter and it turns straw colored.
Indeed, I would prevent higher temperature as to not mess with the temper, especially if the part has been heat treated.
Actually no: The straw color appears first, turning to gold, then purple, then blue and finally black. The blueing in the video has pushed the color past the blue region into the black. He should have heated the part more slowly, not using a torch but rather a bed of hot beads of metal shavings (check Clickspring's excellent video on just this procedure). This would give a more even color and would allow for removing the part when truly blue, as the metal goes through the various colors in well under a minute ( a few seconds with a torch as strong as that of the video).
Also too hot when dropping it in the oil and the oil will boil and cake on the metal instead of soaking in
Don't go using this on gun parts. Getting the steel that hot will ruin the hardening and tempering of the steel.
Which oil is best for bluing?
I am not sure which type of oil is best for bluing, a lot of people recommend light oils like vegetable oil or hydraulic oil, some even suggest water. Personally I have gotten really good results with vegetable oil.
Is it safe to heat a revolver cylinder this much?
I am no expert at bluing guns but I would apply cold blue in this situation to prevent heat distortion.
So what is the ideal temperature?
It kind of depends on the result you are looking for. When you heat up steel it will start to change color, dipping it in oil at the right time will preserve that color. I like to heat it up to around 280 C (540 F) www.quora.com/What-is-the-temperature-of-steel-when-it-is-heated-to-a-blue-color
Would this affect the hardness of the steel?
The temperature at which steel starts to blue is a lot lower than the hardening temperature, when the molucule structure is affected by heating and quenching. There should be no difference in hardness.
@@EngineerSteve Nonsense. Any temperature over 400'f begins to ruin the hardness of steel. When i temper the knives i make, i heat till 450'f which makes the steel turn a straw color, and that is what makes super hard brittle steel into a tough usable steel. The actual hardening process prior to tempering requires temps of over 1450'f though.
Isn't this just oil polymerization like seasoning on a cast iron pan?
I think polymerization really creates a layer by heating up oil/grease, while bluing steel is more of an oxidation proces. But then again I'm not a specialist in that specific field so I could be wrong.
@@EngineerSteve i think your right but im not sure if when you dip the part in the oil it's polymerizing the oil onto the steel or causing some sort of reaction for it to oxide a certain way
@@jlh357 My (limited) understanding is that the steel oxidizes when you heat it up, thus discoloring the steel to a blue color (the color depends on temp.) The oil then cools down the steel, leaving the oxidized color. The chemical details of the rust protection by oil is not known to me, but I will look into it.
Can you do this with stainless steel
I have yet to try this process on stainless steel, of course the purpose of bluing is rust prevention, which is not that much of an concern on stainless. If you are aiming for discoloration you can surely change the color of stainless by just heating it.
would that works with firearms?
I guess it would work but usually the process used on firearms is cold bluing if I am not mistaken: czcams.com/video/vS_foo5ktuo/video.html
@@EngineerSteve cold bluing is used more as restoration, where as production or professionally done firearms are hot bluing process
@@1rex01 Thanks for the information! I'm not really an expert on that.
This is not hot bluing and it wont help much with rust prevention. You can fire blue parts this way but this isnt hot/salt bluing.
Does it have to be vegetable oil
Not necessarily, I chose for vegetable oil because it is cheap and accessible. It will work with other oil as well, I am unsure whether the results will be different or not.
@@EngineerSteve Can you blue a part over and over again to add layers of blueing? sorta like hot salt bluing?
this is heat treating/case hardening
No, for heat treating the part needs to be much warmer, the molecule structure will not be affected that much when hot bluing.
You're right, this isnt hot bluing.
This isn't hot enough to case harden. It's also hot enough to ruin your steels hardness.
heat and vegetable oil? THATS IT?!?!
Heat (the right amount) and any type of oil, yes that's it😉
@@EngineerSteve That's interesting. I'd be worried about doing so with firearms parts as that may ruin the temper and present a safety issue.. but this is cool nonetheless.
@@MausTanker I would not advise doing it on vital gun parts for the concern that you mentioned. Cold bluing seems more suitable for that purpose, I would imagine.
@@EngineerSteve still very cool to know!
Hot bluing basically destroys your part, since it´s a head treatment technique. It´s also the worst method to prevent corrosion in steel. It´s only a very very thin layer which needs constant oiling.
Do zinc plating or painting instead if you want to preserve your parts structure not cause warpage and get better corrosion protection.
The temperature to which the part is heated, barely changes the structural strength of the part. The annealing temperature for steel is around 815 C (1500 F), where as hot bluing happens closer to 290 C (550 F). I hope this clears thing up, rust protecting properties are not that good indeed but hot bluing has its use cases. Have a nice day.
@@EngineerSteve Hardening temp is a range depending on material of about 800°C-900°C However, temperatures as low as 250°C have an influence on the parts structure.
That´s why parts have to be annealed in an oven after heat treatment which makes them hard and brittle, to simply gain their ductility back.
As you can see hot bluing is in a range where the material structure is influenced, not as much as hardening does but still sufficient enough to change the part properties for certain applications.
Martensitic structures within the steel already change at 150°C.
@@sierraecho884
True, I guess it depends on the application of the part, whether or not you want to risk disturbing the structure with heat.
@@EngineerSteve Exactl! Hot bluing parts should be a good idea right after you forge them, since you have to heat treat them anyway, so you can just dip em into some oil and later on anneal the part. Honestly this is the biggest disadvantage of steel which I hate, it´s super prone to corrosion unless you use Chrome in the alloy.
Hot bluing isn't done like this. It's done using boiling water and some real nasty chemicals.
This is not bluing.
There seem to be a lot of contradicting opinions on wheter this is hot bluing or not. All I know is that this process is also known to people as hot bluing but I'm not expert.
That's not black ! Or even blue come to that .
This process is commonly referred to as'hot bluing' my best guess is that the metal oxidizes to a blue colour (by means of heating it) before being cooled down in oil, hence the name
The first half of the video is called tempering not hot bluing
I don't really agree with that, you need to heat up the part to a certain temperature, to which the color is a good indication. My torch is not that powerfull so it took a while, that's why it looks like tempering.
Gave up, sorry i can not understand you.
Lol you're goofy
just say you're stupid lol
This is not hot bluing; hot blueing uses an alkali solution at elevated temperatures to get the reaction. What you are doing here is a type of bluing, but it's closer to seasoning a cast iron skillet than actual "hot bluing". From Wikipedia:
The "hot" process is an alkali salt solution using potassium nitrite or sodium nitrate and sodium hydroxide, referred to as "traditional caustic black", that is typically done at an elevated temperature, 135 to 155 °C (275 to 311 °F). This method was adopted by larger firearm companies for large scale, more economical bluing. It does provide good rust resistance, which is improved with oil.
en.wikipedia.org/wiki/Bluing_(steel)