Acid etch monosteel pattern?

Goot

Goot

Well-Known Member
Hey! I'm working on my third knife and this is the first time I've tried a stonewashed acid etch. After the etch, I noticed an irregularity in my 1080 steel that appears on both sides with a matching pattern. In the pictures, you'll notice a color change just before the ricasso. Is this from not cleaning it well enough (I thought I did), or from the manufacturing process of the bar stock? If so, would this cause a strength issue?

Camp knife
https://imgur.com/a/ZGcKkSU
 
So, it looks like it isn't fully hardened. That darker band is consistent with the transition zone on a hamon. Below the bottom line is unhardened, in between mixed, above hard. The fact the sides match pretty close supports that. 83EA1BD6-755F-4194-9B05-80CE6FE9ABF0.jpeg
 
Just re heat and quench. So long as it wasn't over heated or anything you should be good to go.

Will your whole blade fit in your quench tank?
 
Yes. I have a two brick forge that makes it difficult to heat up a larger knife like this. I thought I got the whole thing (minus the bottom of the tang) to nonmagnetic but I guess not. I'll try again.
 
I had the same issue with a MAPP torch and coffee can forge. The area by the plunge cut often didn't get heated enough. The steel there is thicker and takes more to get to temp properly.
 
I'm glad I can salvage it but what a time-waster. I think I'm going to go for a HT oven. I'd like to eventually make things out of metals that are more difficult to heat treat at home, and I think this failure is the impetus to finally get me to pony up the cash.
 
Goot said:
I'm glad I can salvage it but what a time-waster. I think I'm going to go for a HT oven. I'd like to eventually make things out of metals that are more difficult to heat treat at home, and I think this failure is the impetus to finally get me to pony up the cash.
Click to expand...

You won't regret an oven. It will eliminate this problem you're experiencing. Sound decision.
 
Goot said:
I'm glad I can salvage it but what a time-waster. I think I'm going to go for a HT oven. I'd like to eventually make things out of metals that are more difficult to heat treat at home, and I think this failure is the impetus to finally get me to pony up the cash.
Click to expand...
good choice. I really like your makers mark.
 
Ok, so I heat treated, tempered, sanded and etched a second time. A new pattern came out. This time I was sure to nail the heat treat as best as I could. What gives? Is my etchant too strong? Am I still messing up the heat treat?

I have a 50/50 etchant mix and I do two cycles of eight minutes. And I made SURE to get to nonmagnetic from the tip to as far down the tang I could possibly go, and held it there for an extra two minutes. Good thing this was my prototype blade.

The grain pattern has shifted but it's all over the blade now, and it's very slightly pitted. 1084 btw.

https://imgur.com/a/vJmDYBy
 
That's a pretty strong mix and a pretty long time to etch for a monosteel blade.

It's hard to tell from the pic exactly what the pattern is. It could be banding/carbon segregation, decarb or a contaminant from the etching process. Or a mix of two or three of those things.
 
I usually use a 1 part acid added to 4 parts water to etch blades and damascus. Takes only a minute or so, I usually do 2 or 3 dips, depending on how dark I want it to get.
 
J. Doyle said:
That's a pretty strong mix and a pretty long time to etch for a monosteel blade.

It's hard to tell from the pic exactly what the pattern is. It could be banding/carbon segregation, decarb or a contaminant from the etching process. Or a mix of two or three of those things.
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Interesting. The etchant is brand new, just mixed. It does appear like some type of "organic" banding, which was modified somewhat after I did a new heat treat. I sanded it to 320 grit bare metal prior to the etch and scrubbed it well with 0000 steel wool after each etch.

I followed the etching instructions via red beard ops on YouTube who uses the same mix ratio. I'll try shorter etch dips next time because I'm not sure it's the heat treatment anymore.

Also, I can't find picture examples of "overetching" steel on google. I'm trying to compare images but no luck. Anyone else know of any examples?
 
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How much grinding did you do after heat treating? And how did you measure the austenitizing temp?

Also, what did you clean the blade with prior to any etching?

The answers to these can help us narrow down the cause and trouble shoot.
 
This is the second heat treat, so I didn't grind at all. Just hand sanding to get rid of the decarb layer and then cleaning it multiple times with isopropyl alcohol wearing latex gloves. Should I ditch the alcohol for acetone?

My gut reaction is leaning towards leaving it too long in the acid, which is showing pitting. I can test this theory using a piece of scrap. The previous etch did show an incomplete heat treat, which I guess was a blessing in disguise. I appreciate your help!
 
I'm not sure just hand sanding would be enough to get rid of the scale or decarb. Especially if it was heated in a forge with no real way to know temperature. Some actual grinding would be my preference, second heat treat or not.

Etching in a 50/50 solution for 8 minutes would probably be my first suspect for the putting.

I wouldn't ditch the alcohol for acetone. I've actually seen acetone leave a fine rainbow film on shiny steel and I personally don't use it. I like to wash my blades with hot water and dish soap prior to etching.

The picture does appear to show some sort of pattern that could be carbon banding or decarb or both.
 
J. Doyle said:
I'm not sure just hand sanding would be enough to get rid of the scale or decarb. Especially if it was heated in a forge with no real way to know temperature. Some actual grinding would be my preference, second heat treat or not.

Etching in a 50/50 solution for 8 minutes would probably be my first suspect for the putting.

I wouldn't ditch the alcohol for acetone. I've actually seen acetone leave a fine rainbow film on shiny steel and I personally don't use it. I like to wash my blades with hot water and dish soap prior to etching.

The picture does appear to show some sort of pattern that could be carbon banding or decarb or both.
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I lied. I forgot that I used a blue scotch brite belt to take off the last bits of stubborn decarb, dipping the blade in water when it got warm.
 
Goot said:
I lied. I forgot that I used a blue scotch brite belt to take off the last bits of stubborn decarb, dipping the blade in water when it got warm.
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Scotchbrite will definitely not get rid of decarb! It may get rid of some of the forge scale which is on the surface, but decarb is in the outer layer of the steel. You will need to grind past it or use a heavier grit sandpaper to sand past it. I also do as John does, dawn dish soap and hot water...once I rinse the soap off I go straight into the enchant while it's still wet to prevent streaking from wiping it off
 
JeremyBartlett said:
Scotchbrite will definitely not get rid of decarb! It may get rid of some of the forge scale which is on the surface, but decarb is in the outer layer of the steel. You will need to grind past it or use a heavier grit sandpaper to sand past it. I also do as John does, dawn dish soap and hot water...once I rinse the soap off I go straight into the enchant while it's still wet to prevent streaking from wiping it off
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My mistake, I guess I conflated the two terms of decarb and forge scale. Is decarb bad? Prior to my initial HT I ground to about 80-90% and then finished up afterwards, resulting in a similar pattern after my etch as the second.
 
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