New Moro kris

[apolaki]

What are some signs of corrosion to the blade for leaving it in too long in 5% vinegar acidity?
I noticed the tip of blade has some split in the center. It may have already had that condition however. I did not notice til now.

But are there other signs of corrosion or over exposure has occurred?

Originally Posted by Sajen

I personally would have cleaned the blade by hand with different grain size sanding paper. By this grade of oxidation it's a very easy work IMHO.

Regards,
Detlef

[apolaki]

How do you polish moro blades? I was going to soak blade in bi carbonate slurry then drench in wd40 and later mineral oil when wd40 dries

[Sajen]

Originally Posted by apolaki

How do you polish moro blades? I was going to soak blade in bi carbonate slurry then drench in wd40 and later mineral oil when wd40 dries

Hello,
Here a thread: http://www.vikingsword.com/vb/showth...highlight=moro where I restored a kris blade with similar grade of corrosion, I polish the blade with different grade of sandpaper, you can use it dry or with oil, in your case I woud start with 180 and go up until 1000, make the blade free from any oil and etch it with a warm vinegar solution. The result you can see in the given thread. There are other threads from me and other members where you can see how moro blades can get restored. A bath in a vinegar solution to loosen hard and extreme corrosion isn't announced by a blade with this grade of corrosion IMHO. A bath in a vinegar solution let become a blade gray and when you want to get a good looking blade you will need to polish it anyway.
BTW, to strip down a Moro kris handle is a project, special to built it up again, you need some skill to do it. The handle from your kris is in a very good original condition, I would hestitate to dismantle it.

Regards,
Detlef

[Ian]

Apolaki:

I would remove the blade from vinegar at this point. Rinse it thoroughly in plain water. Wipe it dry and apply a light oil. From here on I would use sand paper only. Start with nothing coarser than 200 grit. Then move to 400 grit and then 600 grit. Wipe the blade regularly with a clean cloth to remove residual particles. Rubbing with abrasive paper will remove any remaining oxidation and polishes the blade to a smooth finish.

After removing the blade from the vinegar it should be apparent if you have any lamination, hardened edge, etc. Signs of these will disappear as you polish the blade. If you wish to show those features again, you will need to etch the blade again.

First, clean off all the oil on the blade (I use propyl alcohol). Then for final etching, I prefer diluted ferric chloride solution although lemon juice works well also. (If the etch looks brown you have left it too long--repolish the blade and start again). After obtaining the desired features, neutralize the acid with baking soda, rinse thoroughly with clean water, dry gently, and again apply a light coating of oil to the blade. Instead of oil you could use a silicon-based wax--I use Renaissance Wax.

Ian

[kai]

A lot of reasonable advice - we need pics/close-ups though to fine-tune any recommendations!

[kai]

Hello Apolaki,

Please verify whether the thin metal strips (which attach the clamps to the hilt) run under the grip binding or entering into the wooden core of the hilt (together with the tang and resin).

If the latter, heating the blade will allow you to remove the hilt and then the clamps (and reassemble everything after restoration). This will greatly ease working on the blade!

If the former and bindings are tight, the metal strips can sometimes be removed from the clamps (tends to be tricky if at all possible) and the hilt/clamps removed, too.

Otherwise, you're out of luck and need to invest in lots of patience and elbow grease...

Regards,
Kai

[kai]

How do you polish moro blades?

I was being a bit liberal with my parlance when suggesting polishing - I rather meant fine grinding and polishing. Anyway, that's pretty much an art (possibly several) and not easily explained.

There's a bunch of suitable abrasives for working steel surfaces by hand (aluminium oxide, aluminium carbide, silicon carbide, diamond being the most prominent), and even more formats in which they are sold depending on application; and certainly thousands of methods/strategies how these are brought into action and results optimized for given tasks/problems. Stick to a single rule: Never ever use power tools!

Your kris blade is in a pretty good shape overall; the thickest and probably most stubborn areas of corrosion/rust will be at the base of the blade; how you target this area may also effect your work strategy on the main part of the blade. If the clamps need to stay in place, this will make the work much more difficult to start with (regardless of method).

Sand paper is widely available but note that qualities vary by several orders of magnitude - cheap paper is usually not worth the hassle. If you go this route, I'd suggest to go for micro-mesh which is more forgiving. The surface may be a bit dulled from the vinegar or you may wish to grind out some scratches - I'd recommend not to try a full polish which will result in more loss of metal than really needed in this case. Choosing the best grit/grade to start with needs some experience (if you start with a too coarse grade, you introduce too many/heavy scratches and need to remove more metal. To avoid making mistakes, I'd suggest to start with really fine grit (= high number) and only work on a tiny "window" of the blade; avoid using pressure and check after some effort. If the result is not convincing, use the next grit on another window and so on until effort and finish seem to suit (without introducing unnecessary scratches). Then use this grit (or the next coarser one) to tackle the base of the blade first. For the base of the blade, abrasive rubber blocks may be easier to work with than micro-mesh. If dismantling works, I'd thoroughly degrease and treat with vinegar first!

Once the whole blade is "clean", successively work through the finer grades (etching between the last few grades can help the final etch); for this polishing/etching process you won't need any final grade with nominal particle size much smaller than 10 μm (verify since the grading numbers are not consistent between vendors much less harmonized internationally). A quick final etch (vinegar, citric acid, phosphoric acid, etc.) can be topped off with an extremely fine polish (and microcristalline wax) if so desired.

Regards,
Kai

[kai]

Hello Apolaki,

What are some signs of corrosion to the blade for leaving it in too long in 5% vinegar acidity?
I noticed the tip of blade has some split in the center. It may have already had that condition however. I did not notice til now.

I believe I can see the forging flaw already in the pic you posted originally.

Hairline cracks and pitting are not cleaned by surface grinding/polishing (unless removing heaps of metal). That's the pro side of vinegar - it helps to really clean a blade thoroughly!

If any pitting or cracks are deep, it will take time and repeated picking of stubborn areas to really clean them out. Depending on the extent of corrosion, the blade may look quite bad (not expected with this kris); however, a thorough cleaning will do much for long-term conservation (if stored properly) and remaining craters/cracks can be filled with hard wax to seal them off.

The surface will get somewhat dull from vinegar or other acids (or even porous if you over-clean). The more you invest in careful manual removal during the initial cleaning/etching, the easier is the polishing afterwards which will get the metal shiny again.

Regards,
Kai

[apolaki]

I have left the blade in a vertical bath of 5% vinegar for a couple days and tried to clean it a couple times by running water over it and scrubbing.

The dark smudge develops really fast after resubmerging in the vinegar. It develops thick again at both sides, and when I take it out of the bath to rinse it off with water and scrub it smells REALLY RANCID AND PUNGENT!!!! (Is it a toxin or hazardous to inhale)? My mind may be going overboard, but I wonder if it's arsneic or something? Any way, I was scrubbing it with a plastic brush very hard with citric dish soap thinking it will scrub the black smudge away, but it didnt seem to do much.

Then I realised that the black smudge actually fades away when the blade dries. The last photo shows what it looks like when it is almost completely dry. Is the rust not being removed or am I making some progress?

Thanks!

[Battara]

Uh..........maybe a little over etched. You may want to repolish and etch with a little distilled water, or don't leave the blade in that long.

[Sajen]

Originally Posted by Battara

Uh..........maybe a little over etched.

Hello Jose,
I think that we don't see an intended etch, it will be the result of the bath in 5% vinegar solution to loosen the rust.
That's what I said before, the blade need to get polished anyway after the bath. The blade wasn't corroded so much that the bath was required.

Regards,
Detlef

[Ian]

I agree Detlef. This blade needs some sand papering and polishing, then a final etch. The red area in the bottom picture is active oxidation that needs rubbing off also.
Ian

[Battara]

Oh.........I misunderstood.

[kai]

Hello Detlef,

The blade wasn't corroded so much that the bath was required.

I beg to differ: There are several deep cracks which surely were filled with rust. There is no way that a gentle polish of the surface would have removed these pockets of residual rust. Thus, for long-term preservation a limited acid soak was not a wrong strategy; with good planning, the process could have been shortened though.

Hardly any harm done in this case - we all have seen much worse restoration attempts, I believe!

Regards,
Kai

[kai]

Hello Apolaki,

Please try to answer those questions raised in post #18.

Regards,
Kai

[Sajen]

Originally Posted by kai

I beg to differ: There are several deep cracks which surely were filled with rust. There is no way that a gentle polish of the surface would have removed these pockets of residual rust. Thus, for long-term preservation a limited acid soak was not a wrong strategy; with good planning, the process could have been shortened though.

Hello Kai,
I have polished several moro blades with a much harder grade of corrosion without a bath in a vinegar or citric acid solution before, not one of this blades show until now new active corrosion.
But in general I agree, it can't hurt! I only want to state that it wasn't really required. And a more easy way would have been a direct polish.

Originally Posted by kai

any harm done in this case - we all have seen much worse restoration attempts, I believe!

For sure! So please don't push Apolaki to remove the hilt. Who get a small shock when he realize that he need to polish a blade (sorry Apolaki ) will have a great problem to fix the hilt later again proper. All my Moro kris blades I have restored by self never I have dismantled the hilt, the result is in many cases visible at this place, just search a little bit.
Yes, it's a little bit circuitous to polish a kris blade with attached hilt but for sure more easy as to dismantle a hilt and more to reattach it proper again IMVHO.

Regards,
Detlef

[Ian]

Originally Posted by apolaki

... when I take it out of the bath to rinse it off with water and scrub it smells REALLY RANCID AND PUNGENT!!!! (Is it a toxin or hazardous to inhale)? My mind may be going overboard, but I wonder if it's arsneic or something? ...

Foul smelling liquids are often contaminated with bacteria and molds. Vinegar contains plenty of nutrients for microorganisms to grow in an aqueous medium. When you say it smells "rancid," I think you are referring to products resulting from microbial contaminants rather than a toxic gas being emitted from acid contacting the metal of the blade.

One possibility might be hydrogen sulfide ("rotten egg gas") if there is any sulfur in the metal. I've not heard of this being a problem with acid etching of steel/iron. Perhaps others have some more information on that possibility. Otherwise, I think your term "rancid" probably covers what is happening here.

Ian