8 months with the Spyderco ZDP-189 FRN Stretch (warning: very picture heavy!)

[spoonrobot]

This thread is basically a compilation of my experience EDCing the FRN Stretch over the past 8 months.

I won't lie, I've been salivating over this knife since the first pictures were posted by Mr Blonde quite a few months ago. My anticipation reached a fever-pitch at the Blade show when I got to handle the prototype and could feel the knife just wanting to cut something, yearning to show off how well it does it's given role.

I recently managed to capture a second-hand ZDP Stretch 2 from a nice gentleman up in Michigan. The knife arrived today, in almost new condition, and I immediately set about messing with it.

First up was a quick dissection to clean, check for perfect function and apply my own thread locker. The last is generally just an extravagance I like to perform but it was a requirement on this knife. I'm unsure if all the S2s or perchance all the ZDP S2s are like this but my example had no thread locker on any of the fasteners. Not a big deal I suppose, just something to be aware of. Lest you be unduly surprised when your pocket clip gets loose.

I am intrigued by the interesting lock-cutout pattern.

Once the knife was all back together (thanks to Mr. Blonde's excellent reassembly thread) I did some cutting. Writing about a specific hobby always brings some inherent problems, there are only so many ways to praise a folding knife. I recently made the mistake of declaring a knife "the sharpest out of the box I've ever seen." Only to have the next two knives prove to be even sharper. This makes it quite hard to be taken seriously, so in light of this I've decided to make slightly less grandiose claims when describing my newest slicey thing.

I don't know if you've ever attempted to do this but it's actually pretty difficult with a very sharp knife. The S2 had those hanging tails popping off the paper.

Couple this with the fact that I was readily able to bisect hairs, not to mention the phenomenal shaving ability, and I think it would be safe to say that the ZDP S2 is sharp enough. You may find a sharper knife out there somewhere but I sincerely doubt it will have come from a factory that way.

Swinging around to the whole knife I would like to clarify my intent. A large part of this review is going to consist of a comparison between the S2 and the Delica 4 and the Endura 4. Quite simply because they share enough in common to be contenders for any serious purchasing recommendation and partly because they make a cute line-up of increasing size and ability.

I've been EDCing an Endura for the past month or so and have spent some time with the Delica as well, making a comparison of the three easily within my ability. I have yet to do more than a small about of cutting with the S2 so actual use updates will come in the future. Just based on handling and appearences it is clear that the S2 serves perfectly in the middle role between the D4 and the E4.

Overall, it's ever so slightly smaller than the E4 and a bit larger than the D4 but the blade of the S2 is actually thinner (due to a significant distal taper) and ground much acute than the D4/E4. Well, it's a FFG, obviously.

(Top to bottom: D4, E4, S2)

 

[spoonrobot]

In the hand the S2 is bumpy in some places and skinny in others. It's familiar, but somehow different. Exciting in a way, it tends to have more of an idea of where your hand should go over the laissez-faire, go anywhere, attitude of the E4. The bi-directional texturing, is of course, the best non-G10 handle type ever devised. So that's good.



That's it for now. I'm going to play with it some more before retiring for the evening and should have some idea of how it feels/cuts in the light to medium role by the end of this weekend. I'll try to pack some sharpening in there as well.
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I've been using the knife quite a bit and haven't much new info to report. It's showing a little corrosion on the side of the blade that faces my leg while being carried in the pocket. This is common in folders I carry since I bike daily and usually get pretty sweaty by the end of the day.

The edge is showing some wear in the form of light chipping and some rolling of the edge. I won't have a good bead on how the ZDP really wears until I get rid of the factory edge and resharpen it a few times. As of right now the wear is typical of a factory edge.

I think the lock cutout may be a cost saving measure.
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A little more than two weeks into my SFRN experience and I've had some things worth reporting.

First, let's talk sharpening. Edge degradation occurred through chipping of the edge.The first two pictures show a chipped section under magnification, the third shows the light reflected off the chip.

Image #2

I used a fine diamond Lansky hone with the Lansky clamp system to sharpen the knife. Overall it was similar to other premium stainless steels. Took about the same time and was of the same difficulty as S30V. Notable difference was that the burr raised in the ZDP was huge! Very easy to feel with the finger and very easy to see. I don't feel the fine stone did a very good job. The edge I put on did not feel as sharp and did not cut as well as the factory edge, I feel I need a finer medium to finish the edge with and will be ordering some Norton stones to try to improve my sharpening of this blade.

Here is a little test I did to make sure it was at least a little sharp. This is acceptable for now; it's a learning process.

 

[spoonrobot]

Next up; the slight corrosion/staining.

I carry the SFRN in my front pocket, down in the pocket. Over the course of the day it is not uncommon for me to pull the knife out and note condensation from the humidity in the pocket on the blade of the knife. The staining is occurring only on the parts of the blade that are exposed when the knife is closed and is noticeably worse on the side that faces my leg. This leads me to conclude that it is from my method of carry and personal biology.

And just to show some of the stuff I've been doing: Other than cardboard and some vegetation; I used to SFRN to section some Salmon for dinner earlier in the week. I found it cut through the usually tough skin very well and the bi-directional texture made for a very secure feeling grip.

While washing I covered the knife in dish-soap and tested some grips. It was a little slippery (duh!) but the rear texture felt like it was catching my hand from slipping too much and the jimping up front provided very good purchase, wouldn't want to cut a bunch of cardboard like this but at least I know it would be at least fairly secure.

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I carry the SFRN everyday. My usual routine is to ride my bike to and from work so I can get pretty sweaty before the day is done due to being in the South. I would bet that the patina would take longer to form if it was winter time. I have noted that the SFRN does not appear to be as prone to staining as my E4. I did a little test with some apple and orange juice from freshly cut fruit. Left it on the blade for about an hour and then washed off, no staining was noted on the SFRN but similar actions caused mild staining on my E4.
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The microscope pictures came from a cheap 40X microscope form the Chinese vendor DealExtreme. It works fairly well but is difficult to take photos through.

I'm not sure if the chipping is specifically from the composition of the ZDP or just from the factory sharpening process. I have noted that with most steels the factory edge will tend to degrade through chipping but after the first sharpening I perform the chipping will be reduced significantly and edge damange will be from rolling. I'll give the SFRN a similar cutting routine with this second sharpening and see how it performs. I don't think the chipping is a real issue, it's just how this steel wears. I find it to be no great loss in performance or maintenance versus other types of edge wear. THG, what have you noticed with your E4? What sharpening system are you using?

I'm an adherent to the thought that fast moving belts and wheels during production heat the edge enough to make it more brittle than the steel will actually be with hand sharpening. Not sure if this is scientifically/metallurgically sound but it's something I've noted in my experiences with factory knives. It is worth it note that my limited experience with serrated knives shows that chipping of that factory edge type is much less than a plain edge in similar steels. This may be due to the fact that SE only has work done on one side so heat is mitigated. I don't profess to be an expert, just trying to objectively report what I see.

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[spoonrobot]

After the sharpening on 10-9-09 I performed similar cutting tasks as done with the factory edge to see if anymore chipping occurred. Sliced up several feet of carboard and then sectioned some 1/4" and 3/8" wooden dowels as well as pointing one of the dowels.

Chipping after the tests. I noted it was much less severe than before and did not affect performance at all. I feel this may not be an issue in the future but will monitor and see if it completely goes away.

Burr that was raised with the Sharpmaker after the cutting tests. This is the first large burr I've ever seen from the Sharpmaker, very interesting in that it was with ZDP. I've found a combination of Lansky diamond hones and finishing with the white stones gives me a more familiar feeling edge that performs closer to the factory edge.

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Rust Review!

So, I've been carrying the knife for about a month. Have used it quite a bit as seen from the previous posts. Today I ended up spending a few hours rolling around underneath my car, fixing a broken exhaust connection. The SFRN in my pocket came out of the job quite gritty from the fine sand and dust that worked it's way into my pocket. Figuring that a full-disassembly would be the best way to get everything clean I grabbed my box and torx drivers and went to work.

Here's what I found:
(The mark on the blade in the second picture is tape residue.)

Quite a bit of surface rust on the liners. This knife is washed in hot/soapy water at least once and week. It was last washed after cutting up some chicken on Thursday afternoon. I generally shake it dry and wipe down the blade with a towel. Lubrication is sometimes added, sometimes not.

Of note is the complete lack of rust or discoloration on the blade, the lockbar and the lock spring. I find this very surprising, not sure if the finish is different or I've just been treating it different but this specific ZDP appears much more resistant to corrosion than my previous ZDP E4. The patina mentioned in previous posts has not gotten any worse, for now it's holding steady.

The rust on the liners is all surface rust with not visible/tactile pitting. It was easily removed with steel wool with only a few small stains remaining.

Also, for whatever reason the small amount of vertical play the knife had is now gone. Not sure if this is from tightening the lockbar screw all the way or just getting some crud out of the action, but right now it is very solid with not up/down play.

 

[spoonrobot]

Looks like the rust is only where the edge of FRN is and where water tend to persists, could it be where you live is too moist and it takes too long to dry?

Could be, but I would expect this kind of corrosion in most climates. Maybe it would be less severe in a very arid and dry climate but it's still water in a very tight space so some corrosion is going to inevitable. It gets extremely dry in the winter here so I'll keep up the regular use and then check it again and we'll see if there was any difference.

I would expect to find rust/corrosion if I completely saturated a knife built like this one in water every week and only shook it "dry".

Of course, I wasn't passing any sort of judgment, just making observations. I use Leatherman multi-tools so I'm used to seeing rust!

I've not noticed any ill effects (literally!) from using folders to handle raw meats/poultry but I do understand the potential issues with using knives that have so many nooks and crannies. But I come from a kitchen background and a lot of my views on knives are based around how a 8" chef knife works in a certain role. By using my folders in a similar role it allows me to experience the ergonomics in a way I'm familiar with a evaluate them accordingly.

Just think what those liners, etc.. would look like in 10 years

Interestingly enough I've been observing another model in a similar role, just with a reduced timespan. Last winter I carried my Khukri folder for 5 months, using it in a similar way to the SFRN. After about 5 months I moved on to a different carry piece so I took the Khukri apart and noted the amount of rust inside the liners. I did not remove any rust and used gloves to take it apart/get it back together to try to reduce the variables. Fast forward another 6 months and I've noted that when not in use the rusting happens either not at all or slow enough that I've noted no change so far. In the long term, I don't know the exact results but I think with a proper application of oil before storage a knife should be just fine for quite a while.

Thanks a lot Sal! It feels good to be able to benefit from the hard work and shared experience of you and your crew. :spyder:



Sharpening!

It's taken me a few weeks to get a feel for maximizing the performance of the ZDP steel but I think I've gotten it down.

Tools used:
11" Norton Medium Crystolon Stone
11" Norton Fine India Stone

Spyderco Sharpmaker

Mother's Mag and Aluminum Polish

I sharpened the ZPD just like any other knife. Started with the medium Norton stone to set a slightly more acute bevel and then moved to the fine Norton stone for finishing. It took a little longer than some of my other knives but overall I didn't notice it being any more difficult than any other steel. The 11" length may have helped! The thing to really work at with this steel is consistency. You can get away with being sloppy with other steels since they abrade quicker but with the ZDP if you fudge the angles it makes it take a lot longer since it cuts slower.

The fine Norton stone produces a fairly coarse edge so for the first few sharpenings I would finish on the Sharpmaker. This gave a good edge but I was still getting some small chipping as the edge degraded. I understand that stropping is a very effective way to remove the small burr but have always hesitated since getting the right equipment requires ordering it off the internet and paying shipping charges that are almost as much as the actual product. I read some posts on bladeforums and found that the Mother's polish was recommended for stropping by a few people. Being that it was available at Wal*Mart I decided to give it a try.

After finishing with the Sharpmaker I applied some Mother's to a piece of cardboard, it doesn't take very much:

And then stropped in an edge trailing motion:

They way I did it was light pressure at the same angle as sharpening. Next time I'll try laying the blade flat to see if it works better. If you want to just remove the burr you only need a few strokes, more than that and you get a very polished edge that push cuts and shaves fantastically.

So far I've noticed a vast improvement in edge life. The steel seems to maintain the high-level edge much longer than before and so far has shown little degradation after quite a bit of use. I feel like I've reached a new level of sharpening capability, evidenced by my first cut in months.

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I was surprised by how easy it was. Took me about an hour to do my ZDP E4 and D4 and the SFRN, this included thinning out the edge angles on all 3 knives. I did not feel it took significantly longer than my VG10 blades. Hopefully this will help some users make a more informed choice in the future.

Oh, and if any one is curious I used Lansky oil on the hones.

 

[spoonrobot]

Stain Testing!

Hey guys! Let's see if we can get some staining going on!

To mimic a quick lunch break I applied various substances to the blades and then let them sit for 4 hours. This is a situation I have experienced before. I get a lunch break and have to hurry and eat with no time to really clean my knife. After the 4 hours I removed the substances with soapy water and checked for staining. The three substances were pineapple juice from fresh cut pineapple, Yellow Mustard and Tomato Sauce.

The three knives are a VG-10 Delica 4, a ZDP189 Endura 4* and a ZDP189 FRN Stretch. The knives were cleaned to remove any oil from the blade before application of the substances.

Here are some pH levels I've found using Google, not sure of the accuracy so if anyone knows of a better source, please chime in.
Pineapple: pH of 3.20-4.00
Tomato Sauce: pH of @4.00
Yellow Mustard: pH of 3.55

Cutting the pineapple:

The knives at the beginning of the test:

Here's what I found:

1: Delica 4 VG-10 (control steel)
Pineapple? No
Tomato? No
Mustard? Yes, the stain is much fainter than the other two blades and has very little coloration. Staining was easily removed with Mother's Mag & Aluminum polish rubbed on the spot with a Q-tip for 30 seconds or so.

2: Endura 4 ZDP189
Pineapple? No
Tomato? Yes, the tomato caused no discoloration but the portion it covered can be seen when the knife is held at certain angles to the light.
Mustard? Yes, The staining occurred both on the edge and the saber portion of the blade. The edge was significantly darker than the saber, with the darkest portion corresponding to a rough area from the medium stones that was missed by the fine stones during sharpening. I do not feel this darker area is rust, application of steel wool did not remove it. This may lend credence to the idea that staining can be dependent, to some degree, on the blade polish

3: FRN Stretch ZDP 189
Pineapple? No
Tomato? Yes, the same as with the E4.
Mustard? Yes, this knife exhibited moderate staining and some rust spotting on the flat grind of the blade. The staining was darker and more obvious on the edge.

Here we can see the discoloration from both the mustard and tomato. Note the staining only occurs where the tomato contacted the blade and not from the sauce.

Tomorrow I'll see if I can remove the staining with either ACV of polishing with various chemicals.

*Note that the Endura 4 was given an Apple Cider Vinegar patina several months ago, this may or may not have contributed to staining resistance. Recalling that I did a mustard test prior to the ACV I feel the staining is almost exactly the same as it was before the ACV patina process. So the ACV made no difference in respect to the Mustard, and I suspect the other substances.

However, after dunking the SFRN blade in apple cider vinegar for 4 hours to remove the staining (which it did quite nicely) I resharpened the blade on my Sharpmaker and then cut up some cardboard.

After only a few cuts I noticed that the edge was chipping extremely badly, worse than anything I've ever seen. This appears to have been caused by corrosion during the ACV bath. So, what did I learn? Corrosion from acidic liquids, dependent on time, may cause significant weakening of the edge structure that won't show up until the knife is used. Now, I'm unsure if this would manifest itself in "real-time" (similar to the much maligned Cliff Stamp D2 wet carpet testing) during use.

 

[spoonrobot]

Back at the end of March I took a trip to the white, sandy beaches of Pensacola, Florida.

While I was there I spent most of a day in and out of the seawater with the ZDP S2 clipped to my trunks. After several hours I was able to rinse the knife with fresh water but was not able to fully clean or lubricate the knife until several hours after that. The knife was not treated in any way, there was some residual motor oil (used for lubrication of the pivot) in the pivot area but no other lubricants were present on the knife. The only rust was observed on the liners and a very small amount on the tang of the knife. Overall I was amazed at the lack of corrosion on the actual blade. The edge was completely rust free and did not appear to have lost any sharpness. I did not notice the massive chipping during use after exposure that came from the ACV bath either, it appears that salt-water based corrosion (or the lack thereof) does not affect the edge in that manner.

The corrosion present after exposure.

So, the susceptibility to corrosion is overstated in the very least that seawater appears to have little effect on the blade steel and actually causes more issues with the liners. In this same vein and somewhat anticlimactically, my FRN S2 ended up clipped to my trunks while I went on a swimming trip to a freshwater lake. After an entire day of in and out water activity it was found that there was no corrosion any where on the knife. No as impressive as the beach trip but still quite interesting to see.

Since my technique has changed a little here's the current sharpening technique I'm using.

If I'm going to rebevel the edge I begin with the 11" Norton medium crystolon stone. I use light pressure and make sure that I'm as consistent as possible with the angle so sharpening time is as efficient as possible.

Once I raise a burr on both sides and am satisfied with the angle I will move to the 11" Norton fine india stone. Same technique as above; light pressure and as consistent with the angle as possible. It's important to spend time and attention on the edge area closest to the pivot. This area is very easy to ignore and you may find the rest of the knife is at the correct angle but the first 1/2" is not sharpened correctly. The abrasion resistance allows you to go back and correct this without messing up the rest of the bevel. You can move the knife down the stone without moving it along the edge and fix it but it's generally easier to be aware of this and accommodate it beforehand.

Once I've gotten a burr on both sides I'll remove it with the Sharpmaker, generally with the white flats are 30 degrees. After the burr is removed as much as possible I'll use the some of the chromium oxide on a short section of leather belt to remove the micro-burr left by the Sharpmaker. I prefer my edge to be on the coarse side of a fine polish so I generally make less than a dozen strokes total, checking for progress with a flashlight or microscope and will stop as soon as the micro-burr is gone.

I'll generally check the edge by shaving or push cutting newsprint. It's good to go when shaving requires no pressure and push cutting can be done without moving the edge at all.

If the edge requires maintenance I'll use the Sharpmaker, 30 degrees with the white flats, it only takes a few strokes per side until the edge gets it's bite back and then I strop as above.

This seems to be working the best for my uses. Edge retention is very good, I can generally go a week and a half to two weeks before I need to touch up. This is with moderate use and cutting things like cardboard, food prep and general use EDC chores. Durability seems good as well, I've accidentally hit staples or other metal/steel items when cutting and the edge has suffered no damage. All in all, I've very satisfied with the steel!

 

[wongKI]

I still miss my Stretch The Gayle Bradley helped, but it's just not as refined a knife.

Thanks for the great review!

 

[somber]

This was a very well written review!
I think I want a Stretch now...
Damn you!


Seriously well done! Thank you for all the insight, you made my re think my sharpening techniques and I'm going to try that mag polish.

 

[spoonrobot]

I'd recommend using the mag polish after some chromium oxide. It will work fine by itself but it takes a lot longer to polish since it's much finer grit. Makes it easier and faster to polish as much as possible with the chromium oxide and then finish with the mag polish. This would give you fairly close to a mirror edge and should be very impressive at push-type cutting.

 

[Sal Glesser]

Very nice Robot, thanx much.

It's one of my regulart EDC's.

sal

 

[knarfeng]

Excellent detailed report. Thanks!

 

[DennisStrickland]

spoonrobot i do'nt believe anyone could say that you did'nt do an in depth definitive review. corrosion as you experienced i consider to be minor --more cosmetic than actual function reducing. my expeience with stretch zdp from last jan thru march gave me little staining & zero chipping. maybe because i finish my blades out on a strop with diamond paste. some of the sharp kings like knifenut1013 may give a review on polished edges vs finish up on white spyderco. my prelim limited experience shows polished edges lasting longer. i intend to pursue this when i get an edge pro.

 

[shangchi108]

Fantastic review. Thanks for posting.

 

[Jason B.]

FYI, waterstones do wonders for ZDP.

 

[1234]

Very nice review !

1234,,,,,

 

[LX_Emergency]

FYI, waterstones do wonders for ZDP.

That's good to know!! I have a Caly3 Carbon Fibre coming in.

 

[zyhano]

excellent review spoonrobot! thanks very much

 

[Pete1977]

great review. did you mod that delica purposefully or was it a refurbish job on a broken blade?

 

[spoonrobot]

Refurbish job.

Thanks for the kind words guys!