Stonewash vs acid wash knife

Stonewash vs acid wash knife DEFAULT

Introduction: Acid/Brass/Stone Washing a Knife

For my first Instructable, I thought I would lay out a step-by-step guide to creating a one of a kind look for any knife. This will work for any knife (actually any item made of steel!), so long as you have large enough containers to fit them in.

Step 1: Safety Notes!

DISCLAIMERS: Don't do this kind of stuff at home if you don't have a basic understanding of high school chemistry. You will hurt yourself BADLY, and I won't be held responsible. Legalese out of the way; onward!

Safety first, you are working with dangerous chemicals.
1. Goggles, eye protection: wear them.
2. Gloves: get some. No vinyl, acetone will melt it. Nitrile is good, rubber is better.
3. Respirator if you have one, the fumes from this procedure can be quite irritating. You may want to complete this outside if you do not have a well ventilated room. Do not purposely inhale the fumes. Don't quote me, but I have read the fumes may contain chlorine gas amongst other things, and chlorine will kill you in high enough doses. Be smart.
4. All bowls, containers, measuring tools, and funnels must be glass or plastic. Metal will corrode!

Another IMPORTANT note, this will void any warranty you have. I'm not responsible if you attempt this and dissolve your blade. Pay very close attention to the timing of your acid bath, and don't etch screws. The acid will eat the threads, and then you're the one who's screwed.

You will also need to sharpen your blade when all is said and done with your desired sharpening methods. These are like fingerprints and snowflakes, extremely individualized, so I won't touch on sharpening much.

Step 2: Required Chemicals & Must Haves

Gather your chemicals. You will need:
1. Muriatic/hydrochloric acid. This is available at almost any hardware store, it is used to clean concrete, and adjust pH of pools.
2. Hydrogen peroxide, the 3% from your local pharmacy is fine. Higher percentages will work faster, and are available at any cosmetic supply store or online.
3. Acetone, used to clean and remove oils from all metal surfaces.
4. Nail polish. This is used as an acid resist, color doesn't matter but I do recommend black or red as it is easier to see and thus remove later.
5. I use the reinforcement stickers as stencils for cleaner lines when applying resist.
Not pictured but also required:
6. Baking soda, this will be used to neutralize the hydrochloric acid etchant.
7. A plastic/glass measuring device, and plastic funnel. Do not use metal as they will corrode immediately.
9. Tumbling "media" and tumbler. Here you will need some type of plastic jar or bottle, I choose to use a 32oz Gatorade jug. You can also use a mayo or peanut butter jar. For media, you will need either a.)7-12 thumb-sized smooth rocks (these can be from a local brook/river or the craft section at Wally World), or b.) +/-50 pistol brass cases, in this case 9mm.
10. WD-40/PB Blaster (any aerosolized petroleum-based oil will probably work) or water and dish soap.

Step 3: Disassembly

Starting with a bone stock knife, you will need to disassemble it completely. A Spyderco Tenacious and Kershaw Chive are both used in this Instructable.
Be sure to separate all screws, standoffs, springs, etc into a secure container. In one photo, you can see I have already begun applying my "resist", the nail polish.

Step 4: Cleaning Parts to Be Etched.

Once disassembled, put on your gloves and glasses, and clean all parts thoroughly with acetone. You must remove all oils from the parts or it will result in a poor etching! From this point on, do not touch any parts without gloves.

Step 5: Applying Resist.

Change your gloves at this point if using nitrile. Nitrile has a "fair" resistance to acetone and at this point is probably at breakthrough.
Apply nail polish/resist to all parts you do not wish to be etched. I recommend using some type of stencil, such as the reinforcement stickers, to keep your work more professional. As you can see, I did not use them on the Chive, and I feel the results suffered.
You will want to pay very close attention to the detent, lockbar surfaces on the liner and blade, the pivot and thrust areas, and all screw holes. Make sure all threads and hole edges are thoroughly painted, even using 2-3 coats. The tolerances on most high quality knives are so close that even the microns removed by the acid can result in changes to the knife's geometry, resulting in "lock rock" and poor action. Change gloves as necessary to avoid getting any "resist" on areas it shouldn't be.

Step 6: Acid Etching

Using a bamboo skewer and some wire (a chain of plastic coated paperclips is better, they won't be dissolved like the wire), fashion a hanger that will allow you to place the parts to be etched in a glass container. Here, I am using an old food jar, but you can also use a flower vase or other glass container. In the photos you will see I have placed the jar in a larger bowl, and surrounded it with baking soda. Baking soda will neutralize any spills.
Using a plastic/glass measuring device and funnel (metal will corrode immediately), add two parts hydrogen peroxide, and slowly add one part muriatic acid to your etching container, and always remember AA: Add Acid. Do not add H2O2 to HCl. The reaction is exothermic (produces heat) and can be violent if you do it wrong. Always add the acid to the hydrogen peroxide! The solution will begin to turn green as it contacts the steel.
Pay attention! The reaction is fast, check every minute or so till it reaches the desired darkness. In the case of the Kershaw, I only etched it for five minutes, the Spyderco was etched for a timed twenty minutes. In reality, with this etchant, more than ten minutes is probably unnecessary.
Something to note: different steels will react to the acid in their own ways. Some will darken more, some cheaper steels will pit and nearly dissolve completely. Heat treats can affect how the steel takes color, with raw untreated steels typically staying lighter. This will affect many fixed blades, as some do not quench the tang, giving it different properties. Pay close attention to unmarked or lower quality knives so you don't destroy them.

Step 7: Neutralizing Acid.

Once the desired time and/or darkness has been reached, I recommend placing the parts immediately into near boiling water. This is a step I use while acid/rust bluing gun parts and results in a darker etch, and helps to "lock" it in. After 30 seconds to one minute, remove the parts from the water and neutralize any remaining acid with baking soda. Any acid will bubble just like the volcano you built in middle school for the science fair. Once neutralized, rinse with clean water and dry thoroughly. VERY IMPORTANT: You must neutralize the acid using baking soda (or ammonia/Windex if you can monitor pH to a neutral 7.0). Failing to do so will cause rusted blades, chemical burns, and general stupidity. Maybe your first born will have a tail, I don't know...

Step 8: Clean Up.

At this point I recommend starting your cleanup. The etchant you mixed can be stored in a plastic container and used indefinitely. It can be renewed by simply adding air using an aquarium pump. Please mark your container well and cover tightly to avoid accidental ingestion or other mishaps. All jars, bowls, and measuring tools must be neutralized with baking soda and rinsed thoroughly!

Step 9: Completing Your New Look.

After neutralizing, you need to decide your next step. You can oil your blade and leave it as is with your new, darker finish, or take it a step farther.
Shown here are both methods I have used. The methods are the same, the only difference is in the media used. You will place your parts one at a time (one part per cycle, very important as the steel on steel can result in damage!) in your "tumbler" and add your media. You can use stones or brass cases. Once this is done, give everything inside a very liberal spray of WD-40/PB, or a mix of water and dish soap (Tablespoon total?). Close up your container and tape it shut.

Step 10: Tumbling

Two options here.
1. Shake the jug until your arm falls off (may result in a more uneven finish), or
2. Wrap your jug in a towel, tape it up (picture is really overkill, one wrap around will do), and place in a clothes dryer. Tumble on Fluff/No Heat setting for 10-20 minutes. Ten minutes results in a light pattern, twenty obviously will be heavier.

Step 11: Cleanup and Assembly

All pieces must now be cleaned of any remaining resist, and grime from your tumbling media. Skipping this will leave you with a very "gritty" knife, one that doesn't open properly. Begin by rinsing thoroughly with soap and water, cleaning off the oils and dirt. Using fresh gloves and acetone (don't NEED gloves at this point, but acetone can be very drying to your skin), remove all traces of nail polish using paper towels, Q-tips, whatever you have handy. Go ahead and reassemble the knives. Check your pivot for that gritty feel, if it's there, take it apart and clean again. Once you have it all cleaned up, I recommend threadlocker (medium/blue?) on all screws, but some will say it's sacrilegious. Adjust your pivot screw to your preferred opening tension, and verified blade is centered. Allow the correct amount of time for the threadlocker to set.

Step 12: Sharpen and Enjoy!

Obviously acid and tumbling will kill your edge, so at this point it will need to be refreshed. You can choose to do this before assembling the knife, entirely up to you. Your bevel should still be solid, so a few quick passes at a lower grit are all that's necessary to break through the finish, followed by higher grits and so forth. I use a Gatco Professional diamond system followed by stropping on canvas, rough leather, and smooth leather (50 laps each) to get that hair popping edge. You can use your preferred method of course. You can protect your new finish with electrical tape if you're using a clamp system like the Gatco, Lansky, Apex, etc.
Finally, it's time to enjoy having the coolest knife on the block! Unless of course you have awesome neighbors who like knives as much as you...

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Types of Finishes on Knife Blades - [Article]

Types of Finishes on Knife Blades - [Article]

by Larry Connelley

When buying a new knife, the type of knife blade finish can offer various advantages, especially when in the field. Here is a quick guide to understanding what each blade finish offers, and how it can add strength, durability, or improve the look of a knife.

Hand Satin Finish: A hand satin finish involves sanding the blade in one direction with increasing degrees of a fine abrasive (generally sandpaper). A satin finish shows the bevels of the blade, showcasing the lines of the knife while reducing its reflective glare. Hand satin finish is generally done on upscale, high-end, collector-grade knives. The finer the abrasive and the more even the lines; the cleaner the satin finish blade looks. Satin finishes can also be used on the handle or fittings to enhance the look of the knife. A nice hand satin finish takes time and can increase the cost of the knife.

Brushed Finish: A brushed finish using an abrasive wheel that creates a satin-like finish pattern. Overall, it provides an attractive working finish without the cost involved with a hand satin finish. It is possible to have a brushed finished blade grinds and combined with hand satin finish flats.

Mirror Polished Finish: A mirror polished finish is done by hand, polishing the metal into a highly reflective surface. While it provides a great look and offers better corrosion resistance due to the smoothness of the blade, this finish type involves a lot of polishing to maintain its look and its reflective quality would be telling in tactical fieldwork. The amount of skill used to create this finish often results in an expensive blade. A mirror finish is quickly scratched when used and is largely a presentation finish.

Blasted Finish: Using abrasive, glass or ceramic beads, the finish is made by blasting the materials at a high pressure against the metal, resulting in an even grey finish. A blasted finish reduces reflection and glare due to its even matte surface. Creating a blasted finish is a base level or user level finish on a knife blade. The blasting creates an increased surface area and micro-abrasions make the steel more prone to rust and corrosion. A blasted blade, even from stainless steel, can rust overnight if left in a very humid environment.

Coated Finish: Usually black, flat dark earth or grey, a coated finish reduces the reflection and glare while reducing wear and corrosion. However, ALL coatings can be scratched off after continuous heavy use, and the blade would have to be re-coated. Generally the harder the finish, the more resistant to wear and the more expensive to add to a knife. High-quality finishes are bonded electrically, chemically or thermally to the surface as opposed to a simple drying paint-like coatings. High-end coatings like DLC (Diamond-Like Carbon) require that the blade goes to a specialty coating facility for PVD (Physical Vapor Deposition) application in a vacuum environment. Interestingly, before being coated most blades receive a blasted finish to have maximum adhesion surface area. Coatings can prolong the life of a blade (especially with carbon steel) by preventing corrosion or rust. Quality coatings add cost to a knife but provide more corrosion resistance, less reflection and require less maintenance.

Stonewashed finish: A stonewashed finish refers to tumbling the blade in an abrasive material. This finish easily hides scratches, while also providing a less reflective nature than a brushed or satin finished blade. There is a wide variety of stonewashed finishes based upon the abrasive shape, tumbling motion and the type of finish the blade has before it enters the tumbler. An "acid stonewashed" or "black stonewash" finish is a blade that has had an acid treatment that darkens the blade before it undergoes stonewashing. The acid oxidation enhances a blade's rust resistance by placing a stable oxide barrier between the steel and the environment. A very positive benefit of stonewashed blades/handles is that they are low maintenance and preserve their original look overtime; the stonewashed finish hides the scratches that can occur with use over time.

Overall, each finish has its advantages and critiques. Depending on what you will be using your knife for, the finish it has can maintain its look or its durability. Knife blade finishes effect the overall cost of a knife and should reflect the intended purpose of the knife. A blade finish is both an aesthetic as well as a practical choice when evaluating knives.

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Pimp Your Knife: Stonewashing

This is the fourth in a series of posts about knife modifications you can do yourself, A.K.A. pimping your knife.

photo 2

photo 1


(Click images to enlarge)

Background Info & Important Reminders

Stonewashing is a super easy knife modification you can do at home. The stonewashed knife above and the instructions you see below are provided with the help of (can anyone guess?) our trusty knife modifier, Parker. He really is the king of knife pimping.

I don’t doubt that other people have different ways of stonewashing, but here’s how Parker does it using materials that are common and accessible. Before we jump right in to stonewashing, though, here are some important things you should know:

  1. Dissembling and/or customizing your knife will void any warranty associated with it.
  2. Stonewashing your knife will damage the blade’s edge. You’ll need to re-sharpen your knife after stonewashing it.
  3. If your knife has a thumb stud and it’s not removable, be aware that the thumb stud may loosen up during the stonewashing process. However, you can easily compress thumb studs using pliers or other tools.
  4. You can stonewash any steel, but coatings should be removed first. However, different finishes will show the stonewash differently. It’s sort of difficult to see the stonewash on Parker’s knife because there’s not much contrast there. A stonewash finish will be easier to see on an acid washed or DLC blade, so if you’re wanting to see more contrast on your blade, those are a couple of good options for you.

On to stonewashing! 



  • Knife (anyone surprised by that one?)
  • Large plastic jar like a mayonnaise jar, or something similar
  • 7–12 small rocks that are no bigger than your whole thumb, but preferably half that size*
  • Nail polish
  • Clothes dryer
  • Large towel
  • WD-40, or dish soap and water
  • Tools to dissemble and reassemble your knife

*Parker gathered some rocks from a stream, which he recommends; rocks from a stream tend to be smoother than ones you find above ground. Parker also said that dense rocks will be best because they will give you more of the dings in your blade that are associated with a stonewash finish than rocks that are less dense. He also tends to use about 7 rocks.



***Again, remember: dissembling and/or customizing your knife will void any warranty that is applicable to your knife. Don’t dissemble, stonewash, or modify your knife if you’re planning on returning it.

  1. Dissemble the knife.
  2. Put nail polish over parts of the knife you don’t want stonewashed, like pivots. You can remove the nail polish after you’re done stonewashing the blade—just use nail polish remover.
  3. Place your rocks inside the plastic jar along with the blade. (If you’re stonewashing additional parts, like a pocket clip, you’ll need to do that separately from the blade. Just do one part at a time.) Spray a little WD-40 in the jar with the rocks, or a little soap and water if you don’t have WD-40. Put the lid back on the jar and make sure the lid is secure.
  4. Wrap the jar in a large towel and secure it so the towel won’t come unraveled. Large rubber bands work great for this.
  5. Put the jar in the dryer on the setting that doesn’t use heat (air tumble, air fluff—it’s called different things on different dryers). Leave it in there for 10–20 minutes. Ten will give you a lighter stonewash while 20 will be a fairly heavy stonewash.
  6. Take the blade out of the jar and rinse it to clean off any residue.
  7. Reassemble the knife and re-sharpen it.


That’s it—easy peasy. If you have any knife modifications you’d like to see, let us know and we’ll see what we can do. (Or any other topics, for that matter.)

Thanks for stopping by the Knife Blog. See ya next Friday.



How to acid stonewash a knife. The basics.

Knife Refinishing: DIY Acid Etching and Stonewashing

In This Article

Including a knife as part of your every-day carry is pretty much a no-brainer. This cutting tool is useful for a nearly-endless list of tasks, whether you're opening boxes at work or splitting firewood in a survival situation. However, let's be real — it's not always all about pure functionality. It's nice to have a knife that both looks cool and cuts effortlessly. If that weren't the case, more of us would end up carrying around simple box cutters, and there wouldn't be as much of a market for high-dollar custom blades.

Knife refinishing steel blade acid etch zombie tools kukri 6

The cool splatter-finish on this Zombie Tools Vakra kukri was created through careful application of ferric chloride...

So, what do you do if you have a knife that works well, but is a bit aesthetically boring? You could retire it and buy a new one, or you could spend a little time and learn to customize your existing knife. Time-tested methods like acid etching and stonewashing are frequently used by major knife manufacturers, and with a little practice and around $100 in materials, you can use these techniques as well.

ZT 0630 knife review 13

The handle on this Zero Tolerance 0630 is made from finely-stonewashed titanium.

WARNING: Before you begin refinishing any blade, take every safety precaution. Be careful to ventilate your work area and wear protective gear. Research the type of steel and acid you'll be using, and any dangerous interactions they may have. Remember that you're dealing with powerful acid and/or fast-moving stone fragments, so protect your eyes and skin. If you don't take these precautions and hurt yourself, don't blame us. This is not an exhaustive guide — we encourage doing additional research to ensure your own safety.

Acid Etching

Acid etching makes use of a chemical reaction between an acidic etchant solution and the steel of your blade. There are many variables here, such as the type of steel used, the type of acid applied, and the amount of time the blade is treated. Etching acids can range from powerful hydrochloric or sulfuric acid to much weaker acids — even household vinegar, citrus fruit, or mustard can be used effectively.

In the video linked above, YouTuber TheSmokinApe acid-etches an ESEE blade with mustard. Yum.

In the video linked above, YouTuber TheSmokinApe acid-etches an ESEE blade with French's mustard. Yum.

However, for the purposes of this guide, we'll discuss one of the most common acid etching solutions in the knife industry: ferric chloride. This etchant is available from most electronic supply stores for about $15 per quart, usually under the name PCB etchant (used for acid-etching circuit boards). Warning: while ferric chloride works well on steel, DO NOT use it with aluminum parts, as it can create a dangerous reaction.Again, research your acid and metal ahead of time to avoid unwanted reactions.

Zombie tools bushlicker bushcraft knife 1

Above:Zombie Tools uses ferric chloride solution to acid etch its blades, yielding a dark and blotchy finish. You shouldn't expect to replicate this exact look without some serious trial and error, especially since Zombie Tools keeps the exact process they use on these blades a trade secret. However, basic acid-etching is also an approachable DIY skill.

Knife refinishing steel blade acid etch diy 2

In the video at the end of this article, Smock Knives demonstrates both DIY acid etching and stonewashing.


Zero Tolerance Kershaw knife factory 086

Often heard in the context of denim fabric and jeans, stonewashing (also called tumble finishing) is a technique that works exactly as you'd imagine — an item is washed in tumbling or vibrating container with water, soap, and an abrasive material. With fabric, this produces a lighter, well-worn appearance. With metal, it can create anything from a finely-textured matte finish to a rough scratched-up look.

Zero Tolerance Kershaw knife factory 093

Above: In our recent tour of the Zero Tolerance knives HQ, we saw how the company uses large industrial machines to stonewash its blades. On a much smaller scale, it's possible to use a similar technique in your own garage.

Zero Tolerance Kershaw knife factory 094

These Zero Tolerance blades were recently stonewashed, and will soon be sharpened.

The end result of stonewashing is highly-dependent on both tumble intensity and the media (i.e. stones) used. Extremely fine media, such as sand or walnut shell fragments, will produce an even matte finish — this is often considered tumble polishing rather than a true stonewash.

Zero Tolerance Kershaw knife factory 099

A Kershaw knife handle scale, before (top) and after bead blasting (bottom).

Bead blasting or sandblasting, which fires these abrasives from a pressurized nozzle, is also used to achieve these lighter finishes. However, these techniques will require an air compressor and media blasting setup, which can be expensive. So, we'll be focusing on the rougher side of the spectrum, as it's easier and less costly for beginners.

Knife refinishing steel blade acid etch diy 3

Stonewashing can be accomplished with under $100 in materials, and these items can be reused on future projects.

Heavier stonewashing media typically consists of literal stones or ceramic pieces, which produce a rougher worn appearance. Increasing the vibration or tumbling intensity or adding unevenly-shaped natural stones can enhance the roughness of this finish.

Materials List

So, what do you need to acid etch and stonewash a knife? Here's a quick breakdown.

Acid Etch:

  • Protective gloves/eyewear and a well-ventilated work area
  • Acidic etching solution such as pre-diluted ferric chloride, available on Amazon or at local electronics stores – $15
  • Acid-etch resist substance, such as nail polish, vaseline, or vinyl stickers
  • Two plastic or glass containers, one for acid and the other full of water
  • Baking soda to neutralize acid
  • Coat hanger or wire
  • Optional: sandpaper, cotton swabs
Other metal parts, such as handle scales, can be stonewashed as well.

Other metal parts, such as handle scales, can be stonewashed as well. This handle was stonewashed, then anodized.


Learn the Techniques

Once you have these materials, the techniques are quite simple. Some fine-tuning and experimentation will be necessary to get the finish you're looking for, so start out with an inexpensive knife. The following video from Smock Knives shows how to perform the DIY acid etch and stonewash process on your blade (or handle, for that matter). We'll also summarize the steps below.

Acid Etch:

  1. Disassemble your knife, and thoroughly clean and dry the part you're going to etch (blade, handle, or clip). Even a single fingerprint will effect your acid etch, so be cautious.
  2. Fill a glass jar with enough ferric chloride to cover the metal part.
  3. Apply resist substance such as nail polish or vaseline to coat any sensitive areas, namely the pivot point, detent, and lock face. This can also be used to paint stripes, lettering, or splatter designs on the blade — feel free to get creative.
  4. Use a wire to lower the part into the acid, being careful NOT to touch the acid. (Alternate method: apply acid to steel in small quantities using cotton swabs, rather than submerging the entire part.)
  5. Leave the part submerged for about 5-15 minutes. Longer immersion will darken and remove more metal.
  6. Carefully remove the knife with your wire, and submerge it in water, agitating to rinse. Apply baking soda to neutralize the acid. Be sure the acid has been thoroughly neutralized and rinsed before touching any item it came into contact with.
  7. Clean the resist substance from the blade. Optional: use sandpaper to remove the resist material and add brushed texture to the blade.
  8. Optional: repeat steps 3 through 7 to etch away more metal.
  9. Store your acid in a safe and sealed plastic container marked “DANGER POISON” for future use.


Stonewashing can be used on its own, or applied after acid etching for a darker worn appearance.

Knife refinishing steel blade acid etch diy 5

  1. Set up your vibratory tumbler, and fill it partially with ceramic stones or other media.
  2. Add some water and a small amount of dish soap to lubricate the media.
  3. Insert your metal part, and power up the tumbler. Run the tumbler as long as needed to achieve your desired finish.
  4. Optional: Insert the part into a sealed plastic jug with stonewashing media, water, and soap. Manually shake, or wrap in towels and place in a clothes dryer on “no heat” setting. This can produce a rougher or more uneven finish.
  5. Thoroughly clean your knife, then oil, reassemble, and sharpen it — check our guide on how to sharpen a knife.

The Results

After following the steps in this article, a reader named Alex sent us the below before-and-after photo of his Spyderco. We'd say it turned out pretty cool — nice work, Alex.

Knife refinishing DIY stonewash acid etch Spyderco custom 1

Planning to try refinishing one of your knives? We'd love to see the results. Snap some photos and email them to me.

Prepare Now:

Disclosure: These links are affiliate links. Caribou Media Group earns a commission from qualifying purchases. Thank you!

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Wash knife vs acid stonewash

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How I Acid Wash and Stone Wash

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