Let's take a look inside my Police 4

Discuss Spyderco's products and history.
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Stuart Ackerman
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Re: Let's take a look inside my Police 4

Postby Stuart Ackerman » Wed Sep 18, 2019 7:27 pm

Pancake wrote:
Wed Sep 18, 2019 12:08 pm
Some days ago I disassemble my Chief and there was some very minor corrosion on the backspacer. And that is linerless G10 and my screws are locktited.....

Corrosion is a bit weird. Last year I made an experiment with my students and we had nails in different environments. The biggest surprised was a nail that corroded in distilled water. Did not expect that for sure.
https://www.quora.com/How-do-metals-rea ... lled-water

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shunsui
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Re: Let's take a look inside my Police 4

Postby shunsui » Wed Sep 18, 2019 11:16 pm

It wouldn't break me up if they put M390 instead of K390 in the Police 4 LW.

FK
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Re: Let's take a look inside my Police 4

Postby FK » Wed Oct 09, 2019 11:14 am

Cambertree,

Yes, classic galvanic corrosion must have Four factors to occur.
1. Dissimilar metals in direct contact.
2. Both metals are immersed in an electrolyte such as water
4. The different metals have different electrode potentials.
The electrode potential is the tendency of a metal to give up electrons and go into solution.
This is the anode vs cathode classic relationship.
5. Presence of dissolved oxygen in the electrolyte. Salty sweat is excellent.

My feeling with the P4 corrosion is the carbon fiber scales which are a conductor is the contributing factor.
This has been observed in the aircraft and automotive industry with many carbon fiber components in current design.

Here is a DOT reference article with detailed explanation:
http://www.tc.faa.gov/its/worldpac/tech ... n17-42.pdf

Ref: page 2 "Galvanic Corrosion"
http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

My question is for other models from Spyderco,,, has anyone observed similar corrosion problems with CF scales ?

Regards,
FK

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sal
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Re: Let's take a look inside my Police 4

Postby sal » Wed Oct 09, 2019 11:20 am

Hi Cambertree,

We used G-10 in the P4 pilot, not carbon fiber, I don't know if G-10 has the same conductor capacity. We've not had problems with CF in this area. Most of our galvanic corrosion issues have been with metals, even similar metals at different hardness.

sal

FK
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Re: Let's take a look inside my Police 4

Postby FK » Wed Oct 09, 2019 11:48 am

Hi Sal,

I am FK the poster you answered.
G-10 is a glass epoxy laminate which has a high dielectric strength, an insulator, and would not contribute to galvanic corrosion as observed by some users of the P4 model. This is the first I have seen with this type of corrosion and was curious if other CF models had similar reports.

Regards,
FK

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Re: Let's take a look inside my Police 4

Postby vivi » Wed Oct 09, 2019 1:57 pm

Wartstein wrote:
Wed Sep 18, 2019 1:51 am
Vivi wrote:
Sat Sep 14, 2019 7:13 pm
James Y wrote:
Sat Sep 14, 2019 6:45 pm
I rusted the liners on my Police 3 in VG10, but that took me 3-4 years of year round carry, and the rust was about 30% of what happened with the Police 4. Don't recall any rust on the blade, backspacer or lock bar on the P3.

I knew the blade on the P4 would require more attention, but I did not expect the same of the liners.
Vivi, looking at your pics of the Police 4 (K 390): Sure, a lot of rust on the liners, not doubt.
But, and correct me if I am wrong: Does that really matter speaking strictly functional?
And how many years would you have to carry the knife without ever cleaning off the rust till it WOULD get a real problem functionwise?

These are honest questions, since I personally never had any serious rust problems whatsoever on my folders, despite carrying them a lot in sweaty pockets and sometimes over days in wet conditions (mostly VG10 though). So I have no real experience here.
Might be, that your enviroment (the air) is a lot more salty than where I live (next salt water around 200 miles away I guess and winds coming from there shielded off by hight mountains)
It could go a while and still be functional, no doubt. Some of my concerns would be:

- Gritty action which would get worse over time, and eventually rust particles would cause uneven wear between the metal parts.
- I would not be comfortable using the knife around food.
- The knife will eventually become very difficult to open and close.
- The smell gets pretty bad after a while.
- The rust would eventually spread to the blade more, and eventually the edge, forcing more frequent maintenance.
- I've seen locks fail due to rust (But not a Spyderco lockback)

At this stage its preventative maintenance, but eventually, left neglected, it would alter the functionality of the knife.

Both my Police folders are still fully taken down. I haven't decided what I'm going to try coating the liners with after I sand out the rust.
Carry rotation:

Pacific Salt 2 SE | Siren | Police 4 LW | Police 4 K390 | C95 Manix foliage green | Manix XL M4 DLC | Street Beat LW | Aqua Salt

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p_atrick
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Re: Let's take a look inside my Police 4

Postby p_atrick » Wed Oct 09, 2019 2:44 pm

Vivi wrote:
Wed Oct 09, 2019 1:57 pm
I haven't decided what I'm going to try coating the liners with after I sand out the rust.
Have you coated your liners before? Has anyone else? I am curious how long the coating will last before it has to be done again. I realize there are lots of factors to this, but if you have to reapply the coating more than once a month, that would become bothersome. Even once a month could get annoying over time. If that's the case, I guess that's why Spyderco has a Salt line.

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Re: Let's take a look inside my Police 4

Postby vivi » Wed Oct 09, 2019 2:56 pm

p_atrick wrote:
Wed Oct 09, 2019 2:44 pm
Vivi wrote:
Wed Oct 09, 2019 1:57 pm
I haven't decided what I'm going to try coating the liners with after I sand out the rust.
Have you coated your liners before? Has anyone else? I am curious how long the coating will last before it has to be done again. I realize there are lots of factors to this, but if you have to reapply the coating more than once a month, that would become bothersome. Even once a month could get annoying over time. If that's the case, I guess that's why Spyderco has a Salt line.
Never tried it but I figure it will help go longer between maintenance. Stuff like this is why I switched to EDCing Salts.
Carry rotation:

Pacific Salt 2 SE | Siren | Police 4 LW | Police 4 K390 | C95 Manix foliage green | Manix XL M4 DLC | Street Beat LW | Aqua Salt

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p_atrick
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Re: Let's take a look inside my Police 4

Postby p_atrick » Wed Oct 09, 2019 3:34 pm

Vivi wrote:
Wed Oct 09, 2019 2:56 pm
Never tried it but I figure it will help go longer between maintenance. Stuff like this is why I switched to EDCing Salts.
Somebody on here said they used bat wax under the scales on their Super Blue Mule. I thought that was a clever solution. I have some Frog Lube, and I don't trust that to last long at all. It is so soft, and it doesn't take much heat to get it even softer. I don't think Frog Lube would stay in place on a hot day with a knife in your waistband.

vivi
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Re: Let's take a look inside my Police 4

Postby vivi » Wed Oct 09, 2019 4:37 pm

I stick to carrying my P4 during the cooler half of the year, and try to avoid IWB. I knew what I was getting myself into before I bought it.
Carry rotation:

Pacific Salt 2 SE | Siren | Police 4 LW | Police 4 K390 | C95 Manix foliage green | Manix XL M4 DLC | Street Beat LW | Aqua Salt

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sal
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Re: Let's take a look inside my Police 4

Postby sal » Wed Oct 09, 2019 9:17 pm

Hi FK,

Sorry 'but that. We're finding in our testing that we don't have all of the answers....yet.

sal

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spoonrobot
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Re: Let's take a look inside my Police 4

Postby spoonrobot » Wed Oct 09, 2019 9:40 pm

Vivi wrote: Both my Police folders are still fully taken down. I haven't decided what I'm going to try coating the liners with after I sand out the rust.
One of the best rust preventatives I've encountered is a hot paraffin wax mixed 8:1 with a lighter oil - I used motorcycle shock oil because it was cheap and available. I've been using it on carbon steel fasteners that get exposed to the elements outdoors and it works excellent - especially if the item has already rusted to some degree. Dip the liner in wax/oil mix, let it cool completely then rub off the dried wax. It makes a extremely corrosion resistant coating, especially for something mostly covered like liners.

vivi
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Re: Let's take a look inside my Police 4

Postby vivi » Thu Oct 10, 2019 1:53 pm

spoonrobot wrote:
Wed Oct 09, 2019 9:40 pm
Vivi wrote: Both my Police folders are still fully taken down. I haven't decided what I'm going to try coating the liners with after I sand out the rust.
One of the best rust preventatives I've encountered is a hot paraffin wax mixed 8:1 with a lighter oil - I used motorcycle shock oil because it was cheap and available. I've been using it on carbon steel fasteners that get exposed to the elements outdoors and it works excellent - especially if the item has already rusted to some degree. Dip the liner in wax/oil mix, let it cool completely then rub off the dried wax. It makes a extremely corrosion resistant coating, especially for something mostly covered like liners.
thanks for the tip!
Carry rotation:

Pacific Salt 2 SE | Siren | Police 4 LW | Police 4 K390 | C95 Manix foliage green | Manix XL M4 DLC | Street Beat LW | Aqua Salt

Bill1170
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Re: Let's take a look inside my Police 4

Postby Bill1170 » Thu Oct 10, 2019 6:00 pm

Cambertree wrote:
Sat Sep 14, 2019 11:36 pm
Pancake wrote:
Sat Sep 14, 2019 10:54 pm
My Police 4 will hopefuly show up next week, so maybe I take some it apart right away and polish the liners a bit with some 500 and 1000 grit sandpaper.
Maybe a even a light coat of some oil or way would help......I made some coconut-beeswax paste for wood so maybe I try that (dont have any fancy waxes or a special paste).
It probably wouldn't hurt to do that. Just be careful not to round over the squared off edges of the liners, or you won't have that nice flush fitting look on the spine.

I was quite surprised when I took mine apart, as I had been wiping down the inside with mineral oil after use and drying it on top of a heater. After sanding mine a bit, as shown in one of the linked posts above, I used Tuf-glide and let it dry before putting it back together.

Wax isn't a bad idea, I'll try Ren wax the next time I take it apart, depending on how effective the Tuf-glide and smoother surface finish has been.

Here's a couple of questions for the metallurgy and science buffs, and please excuse my ignorance:

Does galvanic corrosion always require both metals to be in physical contact with each other?

Is there any mechanism by which a steel can be more susceptible to corrosion by simply having another metal in very close proximity to it?
My understanding is that for galvanic corrosion to occur there needs to be an electrical connection via contact between the two metals as well as via a common electrolyte. Two metals at opposite ends of a water basin made from glass won’t galvanically corrode; Touch them together and the circuit is completed, they corrode more rapidly. Two metals touching where only one of them contacts the electrolyte, again the circuit is incomplete so no galvanic corrosion.

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Cambertree
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Re: Let's take a look inside my Police 4

Postby Cambertree » Thu Oct 10, 2019 6:06 pm

FK wrote:
Wed Oct 09, 2019 11:14 am
Cambertree,

Yes, classic galvanic corrosion must have Four factors to occur.
1. Dissimilar metals in direct contact.
2. Both metals are immersed in an electrolyte such as water
4. The different metals have different electrode potentials.
The electrode potential is the tendency of a metal to give up electrons and go into solution.
This is the anode vs cathode classic relationship.
5. Presence of dissolved oxygen in the electrolyte. Salty sweat is excellent.

My feeling with the P4 corrosion is the carbon fiber scales which are a conductor is the contributing factor.
This has been observed in the aircraft and automotive industry with many carbon fiber components in current design.

Here is a DOT reference article with detailed explanation:
http://www.tc.faa.gov/its/worldpac/tech ... n17-42.pdf

Ref: page 2 "Galvanic Corrosion"
http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

My question is for other models from Spyderco,,, has anyone observed similar corrosion problems with CF scales ?

Regards,
FK
Thanks very much FK for the comprehensive answer. I’ll read those links this weekend.

That’s fascinating about the conductivity of CF. Another plus for G10. And I believe micarta is also an insulator?

Great info, I appreciate the education. :)

Thank you also Bill1170. :)
Last edited by Cambertree on Thu Oct 10, 2019 9:52 pm, edited 1 time in total.

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The Mastiff
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Re: Let's take a look inside my Police 4

Postby The Mastiff » Thu Oct 10, 2019 8:45 pm

Would sealing the liners with say...rustoleum stop the galvanic process all else being equal?

Joe

FK
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Re: Let's take a look inside my Police 4

Postby FK » Fri Oct 11, 2019 9:33 am

Joe,

It will help but not certain of electrical conductivity of rustoleum and relative thickness.
I suggest a polymer based paint of some kind, alternatively you could coat the inside pocket on the CF liners.
Would be an interesting experiment to coat one side only and see what happens to liners.

Regards,
FK

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The Mastiff
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Re: Let's take a look inside my Police 4

Postby The Mastiff » Fri Oct 11, 2019 7:17 pm

It will help but not certain of electrical conductivity of rustoleum and relative thickness.
I suggest a polymer based paint of some kind, alternatively you could coat the inside pocket on the CF liners.
Would be an interesting experiment to coat one side only and see what happens to liners.
Thanks. I first thought of those aerosol rubber sprays as that is fairly non conductive but it might be too thick. It doesn't take all that much to throw it off on reassembly. I know there are many higher tech coatings that I'm not all that current on and some of them need special applications but I'm just talking about inexpensive home testing.

Joe

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sal
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Re: Let's take a look inside my Police 4

Postby sal » Fri Oct 11, 2019 8:26 pm

I'm not convinced that coatings prevent corrosion. I think they do, in some cases, help, but Salt water and sweat can be caustic and find ways to infiltrate. Even humidity near a coast is always trying to eat your knife blade.

sal

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Re: Let's take a look inside my Police 4

Postby Slash » Fri Oct 11, 2019 8:35 pm

FK wrote:
Wed Oct 09, 2019 11:14 am
Cambertree,

Yes, classic galvanic corrosion must have Four factors to occur.
1. Dissimilar metals in direct contact.
2. Both metals are immersed in an electrolyte such as water
4. The different metals have different electrode potentials.
The electrode potential is the tendency of a metal to give up electrons and go into solution.
This is the anode vs cathode classic relationship.
5. Presence of dissolved oxygen in the electrolyte. Salty sweat is excellent.

My feeling with the P4 corrosion is the carbon fiber scales which are a conductor is the contributing factor.
This has been observed in the aircraft and automotive industry with many carbon fiber components in current design.

Here is a DOT reference article with detailed explanation:
http://www.tc.faa.gov/its/worldpac/tech ... n17-42.pdf

Ref: page 2 "Galvanic Corrosion"
http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

My question is for other models from Spyderco,,, has anyone observed similar corrosion problems with CF scales ?

Regards,
FK
WOW, guess I'll start selling all my CF blades now...NOT

Fortunately for me I live in a desert


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