"Bark" on unsurfaced steel

G

grizzled gizzard

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Aug 31, 2010
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Hi guys,

I need to make about 75 smallish stock removal blades out of S35VN as quickly as possible.

In an effort to save time, I'm thinking of having the blades waterjet cut out, and heat treated of un-surfaced steel.

My main question is about the "bark" that comes on rough sheets of steel.

Is it really that much more difficult to grind the bark off?

Is it like scale, that would come off soaking in vinegar?

Would it be easier to sandblast it off?

I've made a batch of knives like this before, and found that grinding hardened S35VN really wasn't a big deal.

Thank you very much for your consideration.
 
Buy the sheets blanchard ground or surface ground, or have the blanks ground before heat treat.
 
Hey Grizz. I am limited to plain carbon steels but I have found that sodium bisulfate diluted in tap water at somewhere between, 1:10 and 1:7 (w/v) works very well at removing forge scale and various other surface crap. Note it WILL eat carbon steel though. Do not leave it overnight like we do with white vinegar soaks or in the morning you may have pitting at best or partially missing blades at worst.

Also I obviously don’t know what effect heavy alloying (e.g. S35VN) will have on the rate of action but IIRC I read this is the same reagent used commercially to “pickle” post-process mill steels of all flavors.

Simple search for “sodium bisulfate + ferrous pickle solution” will give you the real skinny I bet.

Good luck on this project. After 75 iterations – I hope it’s a pattern you admire. ;)
 
I have not used sodium bi-sulfite but will easily take your word as usual Stacy. The reagent I have used for years is sodium bisulfate (NaHSO4-H2O) according to the label in front of me now.
 
OUTSTANDING!!!

Thanks a bunch for the detailed information, Andy! I've always taken Stacy's word "as usual" too. :D

No worries, I'll study up.

Thanks so much for pointing me in the right direction!

I felt like there should be a way to resolve the issue chemically, and keep that money at home.

Huge Thanks and Respect!
 
Yep, any pool supply shop will have what they call Ph minus or Ph down depending on the vendor. Its Sodium Bisulfite and works great for pickling any type/grade of steel.
 
^^^
What Daniel said
 
The whole point of having a batch of blades waterjet-cut is to be more efficient and spend your time where it does the most good - grinding bevels and building knives. Why fool around with pickling several dozen blades?

Buy your steel surface-ground whenever possible. It's basically fool-proof, ends up being less expensive and it's just a lot less hassle in the long run.
 
Last edited:
james terrio said:
The whole point of having a batch of blades waterjet-cut is to be more efficient and spend your time where it does the most good - grinding bevels and building knives. Why fool around with pickling several dozen blades?

Buy your steel surface-ground whenever possible. It's basically fool-proof, ends up being less expensive and it's just a lot less hassle in the long run.
Click to expand...

Bingo
 
Andy Lewis said:
I have not used sodium bi-sulfite but will easily take your word as usual Stacy. The reagent I have used for years is sodium bisulfate (NaHSO4-H2O) according to the label in front of me now.
Click to expand...

Thanks for the catch. Ph down - Sodium Bi-Sulfate. I misspelled it, or the auto-correct changed it?????
 
James has a good point. I don't think pickling would solve all the issues with mill scale, crust, etc as well as surface grinding would. I do know Mr. B has offered to surface grind his high alloy stuff for a fee (Aldo said FEE...not free).

Probably worth looking into for the next batch of steel you buy.

Grizz, a plastic bucket with 3 gallons of hot water, about 3 lb of the sodium bi-whatever crystals and a few hours of doing something fun is easy enough though. I pour out/save the solution then pour in some sand, detergent and fresh water and scrub them off in the bucket then on scrap plywood out back. PPE for face and hands if you go this route. Best to you buddy.
 
Thanks again for the suggestions guys.

I just want to try unsurfaced steel this time. I only do one or two runs of limited edition stock removal blades/year, and I've never tried unsurfaced steel. The only negative thing I've heard about rolled steel is the bark.

If I can throw the blades in a bucket and come back to find the bark gone, that sounds like it's worth trying.

Thanks a bunch for the information on the chemical and usage.

Much appreciated guys.
 
My suggestion would be to buy a small sample of the un-surfaced steel you intend to use, and dunk it into the bi-sulfate as recommended.

When it's done, you should know right away if it's worth the extra buck or two per blade for surface ground steel.
 
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