HAP40 rust?

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Drewski
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HAP40 rust?

Post by Drewski » Sat May 05, 2018 5:26 pm

I was previously storing my Kohetsu HAP40 in a knife block that was made of a bunch of tiny plastic rods. I think once there was a bit of moisture in the rods and a few marks appeared on the core steel of the knife. Initially the marks were dark grey in colour, but after a couple of months, the marks are turning orangish and I'm concerned this is rust.

I foolishly tried to remove one of the spots with 220 grit sandpaper and scuffed up the knife quite a bit. Not very happy with myself about that. So, my question is a 2 parter.

1) how do I get rid of the other rusty spots on the core steel?

2) how do I restore the finish on the core/cladding where I took the sandpaper to it?

Thanks!
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Jeff B
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Re: HAP40 rust?

Post by Jeff B » Sat May 05, 2018 11:26 pm

Use a progression of sandpaper or micro-mesh on the place that you've already sanded, 400, 600 and so on, until you get to the desired finish you want. Might have to go as high as 1k+ to get what you want.
After you get to the grit your happy with you can use that one high grit to remove the rust. You can also try Fltz or bar keepers on the remaining rust before trying the sandpaper. Once you've removed all the rust you may or may not need lightly polish the entire face to blend in the spots where you removed the rust.
If God wanted me to be a vegetarian he wouldn't have made animals taste so good.

jmcnelly85
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Re: HAP40 rust?

Post by jmcnelly85 » Sun May 06, 2018 8:28 am

I’m not sure I see rust in either picture. Take a clean, dry paper towel and wipe the blade, is the paper towel still clean or did it transmit any color onto the towel.

Restoring what the factory finish looked like in one part honestly sounds harder than refinishing the entire side. Use a progression of wet dry sandpaper with a little detergent and you can put a satin finish on in the 400-600 range or take it to a full mirror in the 1-2k+ range.

Wet baking soda slurry rubbed on by a wine cork is a gentle manner to remove rust.

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Jeff B
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Re: HAP40 rust?

Post by Jeff B » Sun May 06, 2018 1:06 pm

Agree with mcnelly about not sure if it's rust but we can't tell from just a picture. His advice is also sound. Doesn't hurt to take it out though if you're unsure since you have another place in the knife to touch up anyway that you've already sanded. And you probably will have to touch up the whole face to get it completely uniform but that is also your call. You might be more than happy with it just touching up a couple places if you do it well enough.
If God wanted me to be a vegetarian he wouldn't have made animals taste so good.

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Drewski
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Re: HAP40 rust?

Post by Drewski » Mon May 07, 2018 9:25 am

Thanks for the advice Jeff and j! In regards to the wet dry sandpaper with detergent, do you just mean to dip the sandpaper in some soapy water?

gladius
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Re: HAP40 rust?

Post by gladius » Mon May 07, 2018 10:15 am

The rust erasers work really well.

https://www.chefknivestogo.com/rustremovers.html

jmcnelly85
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Re: HAP40 rust?

Post by jmcnelly85 » Mon May 07, 2018 7:46 pm

I’m not sure it matters how much soap and water or from where matters. I usually get the blade wet and put a spot of dawn on, get the paper wet and put and put a spot on, then go to town. One trick I learned if you really care about an even finish is change directions when changing grits, once the scratch pattern moving one way completely disappears it’s time to jump again... it can be a time consuming process, or you can keep all lines moving horizontally and just call it a hairline finish and call it a day, it’s up to you how to approach it.

Lepus
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Re: HAP40 rust?

Post by Lepus » Mon May 07, 2018 7:58 pm


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Drewski
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Re: HAP40 rust?

Post by Drewski » Mon May 07, 2018 11:14 pm

jmcnelly85 wrote:
Mon May 07, 2018 7:46 pm
I’m not sure it matters how much soap and water or from where matters. I usually get the blade wet and put a spot of dawn on, get the paper wet and put and put a spot on, then go to town. One trick I learned if you really care about an even finish is change directions when changing grits, once the scratch pattern moving one way completely disappears it’s time to jump again... it can be a time consuming process, or you can keep all lines moving horizontally and just call it a hairline finish and call it a day, it’s up to you how to approach it.
Really helpful! Thanks! Would I still get a hairline finish if I went up to 2k? Sounds like I should start at 400. And it also sounds like I should be making jumps of only 200 grit at a time. Would this be correct if I was going all the way to 2k?

jmcnelly85
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Re: HAP40 rust?

Post by jmcnelly85 » Tue May 08, 2018 12:34 pm

My hairline comment was meant to give an avenue to cheat through it quicker than doing it the proper way, I’m not sure at what point the scratches will become less visible, but after a certain point the lines will be replaced by a mirror effect. Tighter jumps will lead to a better end result, It’s been a while since I’ve bought sandpaper or played with mirror ideas but I think 3m has the grits needed up to 2k.

The satin video is a great resource, I’ve rewatched it a few times. Thanks lepus.

Lepus
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Re: HAP40 rust?

Post by Lepus » Tue May 08, 2018 12:44 pm

Aaron is a good guy doing great work. I rewatched it, too, and it reminded me I need to make one of those sanding blocks. What an awesome solution to a problem I didn't know I had.

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Drewski
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Re: HAP40 rust?

Post by Drewski » Tue May 08, 2018 1:00 pm

Lepus wrote:
Tue May 08, 2018 12:44 pm
Aaron is a good guy doing great work. I rewatched it, too, and it reminded me I need to make one of those sanding blocks. What an awesome solution to a problem I didn't know I had.
Indeed, great video Lepus. Finally accessed it today, videos aren't visible when I'm on the site using my phone.

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Drewski
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Re: HAP40 rust?

Post by Drewski » Thu May 10, 2018 3:56 pm

Picked up a bunch of 3M wet/dry sandpaper. 400, 600, 800, 1k, 1.5k, 2k, 3k. Not exactly decided if I want to go for a full mirror finish, as it seems from what I've read on here that it can be very difficult to maintain. The satin finish from the video posted by Lepus looks quite classy. I'll post pics after I get through with it.

One question: the satin finish in the Gough video comes from polishing to 800 and then going back to the 600 in straight strokes lengthwise. Anyone know what the finish would look like at higher grits? For example, doing 1.5k and then straight strokes with 1k.

Lepus
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Re: HAP40 rust?

Post by Lepus » Thu May 10, 2018 4:16 pm

400 may be a bit too fine to start. You're welcome to try, of coursw, but jt could be frustrating. I would rather go 220/320/400/600 than 400 up.

Dropping from 1000 to 800 will just give you the polish of the knife in the video at 800 with really straight grind lines.

matchplay18
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Re: HAP40 rust?

Post by matchplay18 » Mon Jun 11, 2018 1:42 pm

I just wanted to weigh in great video. It is a scary thing to resurface or try to match a grind profile. I have done this many times do you have a practice knife or some flat stock sitting around. Practice with different grits. Create your own profile but hammered and Damascus knifes are tricky is there any lettering, again another obstacle. Someone mentioned just try to spot the blade in the desired area good advice. But sometimes tell yourself a blade can look a little seasoned in. I have had stains that have etched themselves a little deeper into the porosity of the blade. You will need to know when to quit especially if the knife isn't yours.

datster
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Re: HAP40 rust?

Post by datster » Mon Jun 11, 2018 1:54 pm

There is a lot of good info here, not sure this will be of any value but is what I have learned ..... the hard way, LOL!
Sometimes it's best to leave that little scuff alone and just use the knife, unless it's a show item.
If you don't remove the previous grit scratches completely, as mentioned, they will continue to remain when you move to finer grits.
Any of those "leftover" scratches will start to show up very clearly as you reach a higher polish.
Those "leftover" scratches will continue to become even more pronounced as you continue to attain higher polishes.
The only way to finally eliminate them is to go back to one level of coarseness prior to the scratches and start completely over.
Now, this may not be totally true if you have buffers or special equipment, but armed with sandpaper and water this can be a tedious process.
Oh yeah, one more hard earned lesson once ..... ok, maybe twice because sometimes I do stupid stuff ........ use a rubber eraser, some kind of block, something ...... we all know moving fingers and sharp edges don't end well.

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lsboogy
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Re: HAP40 rust?

Post by lsboogy » Fri Jul 06, 2018 12:01 pm

I have quite a few 60-70 year old sabatiers - all carbon steel and (look it up) Minnesota has the highest dew points ever recorded in the continental US. I learned from my mom years ago to force a patina on carbon knives (she just put mustard on the blades - I pattern some of mine now with mustard and vinegar). Even living in a sauna in the summer months, none of my knives rust. Plus they look cool.

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lsboogy
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Re: HAP40 rust?

Post by lsboogy » Fri Jul 06, 2018 12:11 pm

If you are interested, rust is called "Hematite" - reddish brown. Patina is called "Magnetite" - two forms of iron oxide - patina forms a grey layer that will protect the knife - re-do it every couple of years and your knives will not rust.

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Drewski
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Re: HAP40 rust?

Post by Drewski » Tue Jul 10, 2018 12:25 am

I'm just above Minnesota. Very interesting about the forms of iron oxide. Thanks for the info.

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lsboogy
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Re: HAP40 rust?

Post by lsboogy » Mon Jul 16, 2018 3:08 pm

Force a patina on your knives and be done with it. Best rust prevention nature ever came up with. Your knives will last several lifetimes if taken care of

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