Knife making video questions

[MilwaukeeJon]

 

Two questions: 

 

1) What kind of steel might this maker be using? There appears to be no heat treating during the making of the blade. 

2) What is the darkening solution the blade gets dipped into at the 8:55 or so mark?

 

Thanks in advance. 

[Latticino]

No way to tell what steel the maker is using, but if it is already hardened stock (say a hardened billet of O-1) and his stock removal process was carefully optimized to keep the billet below tempering temperatures (lack of periodic water quench during bevel grinding using a jig makes me doubt this), he could still have a hardened blade when finished.  What makes you think the final product is properly hardened, or even tool steel?  For all we know from the video he could have been using mild steel.

The darkening bath looks like a Ferric Chloride solution to me, but again I'm just guessing.  Why not contact the video producer and get your answers from someone who knows...

[JHCC]

Really should be wearing a mask while grinding.

[templehound]

The shape of the piece of steel shows that it is forged.

The heavy sparking shows that it is already hard...or hard enough to spark like that

According to the carbon explosions and their form the spark picture looks to me like a steel with about 0.8% Carbon. Easy to see at 3:26 where he grinds the back of the blade...but due forging it could have some carbon loss that can make a 1%Carbon steel like 1095, look like 8.0% C...the colors in the video of course are also not true

...so if we had better, true colors the aspect of a piece of forged coil spring with obviously  more than 0,6C could be added to the guessing

.....so it could be 02,...besides this steel you can find in every corner of the world...like Diesel oil.

...and ferric chloride.

 

[JHCC]

5 minutes ago, templehound said:

The heavy sparking shows that it is already hard...or hard enough to spark like that

Isn't sparking a function of alloy content rather than hardness?

In other words, if hardness affected sparking, wouldn't the various spark testing charts show different results for different hardnesses of the same alloy?

[MilwaukeeJon]

Templehound, thanks for the informative answer. 

[ThomasPowers]

As he mentions it is a guess based on his experience. You will have to contact the maker to get the straight answers.

[JHCC]

Just now, ThomasPowers said:

You will have to contact the maker to get the straight answers.

A number of people asked those questions in the comments on the YouTube page, but got no response.

[templehound]

7 minutes ago, JHCC said:

Isn't sparking a function of alloy content rather than hardness?

In other words, if hardness affected sparking, wouldn't the various spark testing charts show different results for different hardnesses of the same alloy?

If You have the carbon bound  due heat treating it will show some of that with the sparks and those have their form and color according to alloy.....

Unhardened low alloy tool steel does spark but it looks different to me....just my 2 cents without guarantee

 

[Latticino]

32 minutes ago, templehound said:

The shape of the piece of steel shows that it is forged

Really?  I didn't study it closely, but it sure looked like he cut it out from a piece of bar stock with an angle grinder to me.  If forged, why not forge the profile at least?  Didn't see any patterning or San Mai layering to justify forging a piece of bar stock and just leaving it as such.

Agree on the "spark-test" that it is unlikely to be mild steel, but I don't have a good eye for that yet.

[templehound]

Well.....like the somehow round end, cut side , sides are not paralel at all....maybe I should say,the shape leads me to believe that it was forged....but maybe he didnt forge, just cut it out and prepared it and after all it looks like this ....also possible

[BIGGUNDOCTOR]

The darkening agent could have been Ospho blue. Most of these cold blue solutions are a phosphoric acid base and leave a black oxide behind. I just picked up a quart jar of Ospho at a garage sale. We used it in the gunsmith shop I worked in and found it helped to heat the part up until it was too hot to hold before coating. 

[D.IVO]

It's  high carbon steel judging by the number of springs on the sparks, it wasnt heat treated nor did he bothered sharpening.

A knife without HT is only a paper wheight.

[MilwaukeeJon]

6 hours ago, BIGGUNDOCTOR said:

The darkening agent could have been Ospho blue. Most of these cold blue solutions are a phosphoric acid base and leave a black oxide behind. I just picked up a quart jar of Ospho at a garage sale. We used it in the gunsmith shop I worked in and found it helped to heat the part up until it was too hot to hold before coating. 

Thanks for the info.