How to Strip a Blade Coating — Acid Etch and Stonewash DIY

ByMarkus

Factory blade coatings serve a purpose — corrosion protection, glare reduction, tactical aesthetics — but they wear over time, and a scratched-up DLC or Cerakote finish can look worse than no coating at all. Stripping a blade coating and applying an acid wash and stonewash finish is one of the most satisfying DIY knife mods you can do. The results look custom, hide future wear beautifully, and cost under $30 in materials. Here’s the complete process.

Safety First

This project involves chemical strippers and acids. Work in a well-ventilated area (outdoors is best). Wear nitrile gloves, eye protection, and clothes you don’t care about. Ferric chloride will permanently stain anything it touches — concrete, clothing, skin. Have baking soda and water nearby to neutralize spills. Do not pour chemicals down drains without proper disposal procedures.

Step 1: Disassembly

Strip the knife down to just the blade. Remove handle scales, washers/bearings, stop pin, and any other hardware. The blade must be bare metal-only for the etching process. Photograph the disassembly if you’re not confident about reassembly. This is critical — acid-etched components won’t fit back together differently.

Step 2: Remove the Existing Coating

For painted coatings (Cerakote, some budget blade coatings), a chemical paint stripper like CitriStrip works well. Apply a thick layer, let it sit for 30—60 minutes, then scrub off with a nylon brush. For DLC and PVD coatings, chemical strippers often don’t work — these are molecularly bonded to the steel. You’ll need mechanical removal: sandblasting (ideal but requires equipment) or wet sanding with 400—600 grit sandpaper (tedious but effective).

If the coating is particularly stubborn, some makers have success with aircraft paint remover (methylene chloride-based). This is extremely hazardous — use only outdoors with full PPE. Modern “safe” paint strippers are less effective but worth trying first.

Step 3: Acid Etching

You’ll need ferric chloride (available on Amazon or electronics supply stores as PCB etchant). Dilute with distilled water — a 50/50 mix is a good starting point. Some users prefer a stronger solution for darker results; test on a scrap piece of steel first.

  • Clean the blade thoroughly with acetone or isopropyl alcohol. Any oil or fingerprint will resist the etch.
  • Suspend the blade in the ferric chloride solution using wire through the pivot hole. Don’t let the blade touch the container bottom or sides.
  • Etching time: 5—15 minutes depending on desired darkness. Check every 2—3 minutes. The blade will turn grey, then darker grey, then near-black.
  • Remove and immediately dunk in a baking soda and water solution to neutralize the acid.
  • Rinse thoroughly with water and dry.

At this point you have an acid-washed blade. The finish is dark, matte, and provides moderate corrosion protection. But it will show scratches from use — which brings us to the next step.

Step 4: Stonewashing

Stonewashing after acid etching creates a durable, scratch-hiding finish. You’ll need a tumbler (a rock tumbler from Harbor Freight is $40—$60) or a DIY shake method. For the DIY method:

  1. Place the blade in a plastic container (a Gatorade bottle works) with ceramic tumbling media, smooth river rocks, or even gravel. Add a few squirts of WD-40 or a bit of water with dish soap as a medium.
  2. Wrap the bottle in a towel, put it in a backpack or duffel bag, and shake/tumble for 10—20 minutes. Yes, this is as ridiculous as it sounds. Yes, it works.
  3. Alternatively, wrap the bottle in towels and put it in a dryer on “no heat” for 30 minutes (remove before your partner gets home).
  4. Check the finish. The stonewash should create a uniform pattern of micro-scratches over the dark acid etch. More tumbling = more wear pattern.

Step 5: Reassembly

Clean the blade thoroughly — you don’t want tumbling grit in your pivot. Use compressed air on the pivot hole, then isopropyl alcohol. Reassemble with fresh lubricant. The pivot may feel slightly grittier than before if any etching compound or stonewash media remains; a second cleaning with cotton swabs in the pivot hole usually resolves it.

FAQ

Will acid etching affect the blade’s edge? Yes — if you don’t protect it. The acid will dull a sharp edge. Most DIYers mask the edge with nail polish or electrical tape before etching. Alternatively, plan to resharpen after the process. The acid removes a microscopic layer of steel, so the existing edge will be gone.

Does acid etching weaken the blade? The amount of steel removed is measured in microns — it won’t affect structural integrity. However, hydrogen embrittlement is a theoretical concern with acid etching high-hardness steel. Keep etch times reasonable (under 30 minutes) and the risk is negligible.

Can I acid-etch and stonewash stainless steel? Yes, but the results vary by alloy. High-chromium stainless (20CV, M390) etches more slowly and evenly than carbon steel. The finished color will be lighter grey rather than near-black. Ferric chloride works on all steels, though some makers add a few drops of sulfuric acid to the mix for stainless.

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