#anodizing #titanium #niobium #making #caswell #metalwork # Quick Start Read [[#Safety]] first — **this process runs at up to 120 V DC, which can kill you.** Plug into a GFCI outlet, keep one hand in your pocket, dry everything. 1. **Polish or finish the part** to your target look. Polished = jewel tones; bead-blasted or scotch-brite = pastel/satin. Sand through at least 800 grit for vivid colors. 2. **Degrease** with the kit's pint degreaser, rinse in distilled water, dry. Don't touch the surface with bare hands after this. 3. **Mix the bath**: 1 lb of Caswell titanium anodizing powder into 1 gallon of distilled water in the included 2-gal HDPE tank. 4. **Rig the cell**: wrap the stainless cathode in the anti-spark mesh, submerge it on one side. Hang the part from titanium wire on the other side. Nothing touching. 5. **Power off**, connect (+) to the part's Ti wire and (–) to the cathode. Plug into a GFCI outlet. 6. **Ramp voltage slowly** (2–5 min) to your target color. Use the [[#Voltage to Color]] chart, not Caswell's old manual chart. Voltage sets color — time at voltage does not. 7. **Hold ~15–30 sec** at target. Power off. Pull the part. 8. **Rinse** in distilled water, pat dry with a clean lint-free cloth. **No seal step.** Done. ==Critical: Caswell's 2012 manual voltage-color chart is wrong. Use Brian Skellie's chart (see [[#Voltage to Color]]).== # Overview Titanium anodizing is **fundamentally different** from aluminum anodizing — it is **not** a dye-on-porous-oxide process. The color is produced by **thin-film interference**: a transparent oxide layer of a precise thickness reflects specific wavelengths of light. Oxide thickness is set by the **anodizing voltage**, not by time or current density. No dyes. No sealing. The whole process takes seconds to minutes. The Caswell **Titanium & Niobium Anodizing Kit** (SKU: TANKIT, ~$541) is a complete cell — it ships with the power supply, electrolyte, cathode, tank, hanging wire, and brush wands. Works on Ti, Nb, Ta, and other reactive metals. **Will not work on aluminum or stainless steel.** # Resources - [Caswell Titanium & Niobium Anodizing Kit product page](https://caswellplating.com/titanium-niobium-anodizing-kit.html) ($541.41) - [Caswell Canada BOM](https://caswellcanada.ca/product/titanium-niobium-anodizing-kit/) (more detailed kit contents than the US page) - [Kit instructions PDF (Emerald Coatings mirror)](https://emeraldcoatings.com/wp-content/uploads/2018/03/Titanium-Anodizing-Kit-Instructions-1.pdf) - [Brian Skellie — canonical Ti/Nb color chart and technique](https://brnskll.com/shares/anodizing/Anodization-c967106) — the industry reference for body-jewelry anodizing - [MonsterBolts Ti color chart](https://monsterbolts.com/pages/anodized-titanium-color-chart) - [TZR Metal — voltage control and burning](https://tzrmetal.com/titanium-anodizing/) - [Caswell forum](https://forum.caswellplating.com) — search Ti/Nb threads - [[Aluminum Anodizing]] — sister note; different chemistry but shared workflow # What's In the Kit | Item | Notes | |---|---| | 120 V DC, 1 A power supply | Included in this SKU — no separate rectifier needed. Standalone version is ~$318 | | 2-gal HDPE tank + lid | Same form factor as the aluminum-kit buckets | | 1 lb Titanium Anodizing Powder | TSP-based electrolyte; mixes into 1 gal distilled water. Drain-safe per Caswell | | 1 pint liquid degreaser | Mild alkaline cleaner — **NOT HF, NOT nitric**, despite what the 2012 manual implies | | 4" × 8" stainless steel cathode | Stainless works fine at these voltages — niobium cathode not required | | Anti-spark protector mesh | Wraps the cathode to prevent arc-through | | Titanium hanging wire | For suspending the part | | 3 pen wands (fine, dome, angled) | For brush/spot anodize technique | | Masking tape (2" × 72 yd) | For masking off areas to leave unanodized | | Protective gloves | | | Instruction sheet | | **Not included — provide yourself:** - Distilled water (~2 gal for bath + rinses) - GFCI outlet (or plug-in GFCI adapter) - Safety glasses - Multimeter (recommended — to verify power supply voltage matches the dial) - Small knife / X-Acto for cutting masks # Process ## 1. Surface Prep Surface finish drives color quality more than any other variable. - **Jewel-tone colors**: polish through 220 → 400 → 600 → 800 → 1000 grit, ideally up to 2000–5000 if you want a mirror finish. Lower than Ra 0.5 μm. - **Satin/pastel look**: glass-bead blast, or scotch-brite (maroon medium pads). See [[Aluminum Anodizing#Roloc setup]] — same tooling works here. - **Mixed finishes**: mask the polished areas with the kit's tape, blast or brush the rest, then strip the tape before anodizing. Break sharp edges slightly. Sharp corners can arc to the cathode at high voltage. ## 2. Cleaning Use the kit's degreaser. **HF is not needed and Caswell does not ship any.** If you want a stronger pre-clean, options: - **Bar Keepers Friend** (oxalic-acid based) — scrub with a non-metallic pad, rinse thoroughly - **Multi-Etch** or **TitanEtch** — commercial HF-free Ti etchers, ~$30 - **Isopropyl alcohol** wipe immediately before anodizing Final rinse in **distilled water only** (tap water leaves mineral spots). Don't touch the surface with bare hands from this point — finger oils permanently mark the anodize. ## 3. Mix the Bath 1 lb Caswell powder + 1 gal distilled water in the included 2-gal HDPE tank. Stir until dissolved. Bath keeps indefinitely if covered. For DIY equivalent (if you run out of Caswell powder): **3–5% TSP by weight in distilled water** (~3 tbsp per gallon for low concentration, ~½ cup per gallon for high concentration). Stronger solution → better low-voltage colors. Weaker solution → better high-voltage colors and brush work. ## 4. Rig the Cell - Wrap the stainless cathode in the anti-spark mesh. Submerge on one side of the bath. - Twist the titanium hanging wire to the part — tight mechanical contact, no oxide between wire and part. Suspend on the other side. **Wire must reach above the liquid line** so the alligator clip stays dry. - Verify part and cathode aren't touching and won't swing into each other. ## 5. Connect Power - **Power supply unplugged**, dial at zero. - (+) to the Ti wire (the part is the anode). - (–) to the stainless cathode (with the anti-spark mesh). - Plug into a **GFCI outlet**. If you don't have one, use a plug-in GFCI adapter — non-negotiable at 120 V DC. ## 6. Ramp the Voltage - Power on. Ramp slowly to target voltage over **2–5 minutes**. Faster ramps cause burn marks and matte spots. - Color appears within seconds of reaching steady-state. **Time at voltage does not deepen the color** — only higher voltage does. - Hold 15–30 seconds at target to stabilize. - Power off. ## 7. Pull and Rinse - Power off **before** touching anything in the bath. - Remove the part by the wire, rinse in distilled water, pat dry with a clean lint-free cloth. - No sealing. The oxide IS the color and is already permanent. # Voltage to Color ==The Caswell 2012 manual chart (yellow at 1–8 V, etc.) is incorrect and contradicted by every other industry source. Use the chart below.== Source: [Brian Skellie](https://brnskll.com/shares/anodizing/Anodization-c967106) cross-referenced with [MonsterBolts](https://monsterbolts.com/pages/anodized-titanium-color-chart). ## Titanium | Voltage (DC) | Color | |---|---| | ~10 V | Light bronze / champagne | | 15–20 V | Gold / dark gold | | 20–25 V | Bronze / brown | | 25–30 V | Dark purple → violet | | 30–35 V | Royal / dark blue | | 35–45 V | Medium blue → light blue | | 45–55 V | Light blue / silvery cyan | | 55–65 V | Yellow / pale gold (2nd-order interference) | | 65–75 V | Pink / fuchsia / magenta | | 75–85 V | Purple / "blurple" | | 85–95 V | Teal / aqua | | 90–100 V | Green → yellow-green | | 100–110 V | Olive / muddy yellow | ## Niobium Niobium colors at slightly lower voltages and gives softer pastels. Pinks and reds are easier on Nb than Ti. | Voltage (DC) | Niobium Color | |---|---| | 9–18 V | Brown / bronze | | 20–25 V | Blue | | 30–40 V | Yellow / gold | | 40–55 V | Purple / violet | | 55–70 V | Pink / red-violet | | 70–80 V | Teal / cyan | | 85–90 V | Green | ## Things the chart doesn't give you - **No true red, no true black.** Interference colors can't produce a dominant red reflection in the 10–120 V window. Black on niobium is possible only via blowtorch heat treatment, then a light polish. - **You can only go up.** Once anodized, you can ramp higher to reach any higher-voltage color, but you cannot step back down. To redo, repolish or alkaline-strip and restart. - **Voltage drifts** with electrolyte concentration, temperature, and alloy. Run a scrap or hidden corner first to dial in. # Brush vs. Immersion ## Immersion Whole part takes a single color. Best for screws, knife scales, bolts, single-color jewelry. Process as described above. ## Brush / Pen Wand The kit's 3 pen wands let you paint patterns, fades, and oil-slick effects. 1. Set the part on a lead from the (+) terminal — alligator clip on a clean spot or a tab masked off later. 2. Dip the pen wand (connected to (–)) into the electrolyte. 3. Touch the wand to the part. Color appears at the contact point. 4. Drag the wand for streaks; dab for spots; build up multiple voltages on different areas for multi-color effects. 5. Rinse with a distilled spray bottle between strokes if colors are bleeding. Brush technique is forgiving for fades (just slowly raise voltage as you move) but unforgiving for sharp boundaries — for clean lines, use masking tape and immersion. # Safety Three real hazards: **electrical shock, alkaline splash, and hydrogen gas.** No HF in this kit. ## Electrical (this is the big one) - **120 V DC at 1 A is potentially lethal.** Much more dangerous than the 15–18 V aluminum process. - **Always plug into a GFCI outlet.** Use a plug-in GFCI adapter if your garage outlets aren't GFCI-protected. - **Power off before touching anything** in the bath, including swapping leads, repositioning parts, adjusting the cathode, or pulling a finished part. - **One hand in your pocket** when adjusting voltage with the bath energized. Two-hand contact across the chest is the classic electrocution path. - **Dry hands, dry floor, dry bench.** Anodizing is wet by definition — set up so spills can't pool around the power supply or your feet. - **No metal jewelry** on hands or wrists while working. - **Never let the part touch the cathode** with power on. Trips the breaker, can damage the supply, and creates a flash. ## Chemical - Caswell's electrolyte powder and degreaser are mildly alkaline. Splash goggles + nitrile gloves. Wash skin if splashed. - The 2012 Caswell manual mentions 25–30% nitric + HF for cleaning — **this kit does not use that and you don't need it.** If you ever switch to HF-based etchants (Whink, Kroll's reagent, etc.), keep **2.5% calcium gluconate gel** on hand — HF causes painless skin entry followed by delayed bone damage. ER trip required either way. For this kit, just don't use HF. ## Ventilation Small amount of hydrogen at the cathode. Work in a ventilated area, no open flames. The garage door open with a fan is sufficient. ## Rules - GFCI outlet, every time. - Power off before touching anything wet. - Distilled water only. - Lid the bath when not in use. - Don't mix metals — the cell is for Ti / Nb / Ta only. # Decisions - **Decision**: Use the included Caswell 120 V / 1 A supply, not a DIY variac+rectifier. - **Why**: It's already in the kit, properly sized for hobby parts (most jewelry/knife scales pull <0.5 A), and ready to go. DIY variac is cheaper but adds project work before I can anodize. - **Alternatives**: 0–140 V variac + bridge rectifier + cap (~$30–80), 120 V bench supply (~$200–500), or 9 V batteries in series (cheap but fiddly). - **Decision**: Stick with the kit's TSP-based powder. - **Why**: Drain-safe, non-toxic, and proven on the Caswell kit. Saves figuring out concentrations. - **Alternatives**: DIY TSP from the hardware store (3–5% by weight in distilled water). Cheaper but I have to dial in concentration myself. - **Decision**: Use Brian Skellie's color chart, not Caswell's 2012 manual chart. - **Why**: Caswell's chart has yellow at 1–8 V — that's an outlier vs. every other published source. Skellie is the industry reference for body-jewelry Ti work and his chart matches MonsterBolts, TZR Metal, and HonTitan. - **Alternatives**: Use whatever chart, then re-anodize. Painful. - **Decision**: Treat 120 V DC seriously. GFCI + one-hand rule + power-off-before-touching, every time. - **Why**: Aluminum process habits don't transfer here — 15 V is a tingle, 120 V can kill you. - **Alternatives**: None. This is the rule. # Troubleshooting | Symptom | Cause | Fix | |---|---|---| | Blotchy / uneven color | Surface prep insufficient; tap water in bath or rinse | Polish higher, degrease longer, use distilled only | | Burned matte spots radiating from contact | Loose Ti wire contact, voltage ramped too fast | Tight wire twist, ramp over 2–5 min, lower target | | Color is "off" from chart | Electrolyte concentration drift, alloy variation, temperature | Run a scrap first, dial in by 1–2 V at a time | | Wrong color and I can't go back | You can only ramp up, never down | Repolish or alkaline strip, restart | | Fingerprints in the finish | Touched the part with bare hands after cleaning | Hold by wire until rinsed and dry, every time | | Bath fizzing aggressively at cathode | Normal — hydrogen evolution. Just ventilate | — | | Breaker trips / power supply shuts down | Part touched cathode, or short via wet hardware | Power off, dry everything, separate electrodes, GFCI did its job | | Matched parts don't match across sessions | Voltage repeatability + bath drift | Anodize matched parts in the same session, at the same time | | Same voltage gives different color over time | Bath concentration changes as water evaporates | Top off with distilled water, or re-mix | # Stripping Ti Anodize Stripping titanium anodize is **not like stripping aluminum anodize.** Lye (NaOH) does *not* work — titanium oxide is kinetically inert to alkali at room temperature. The aluminum-anodize NaOH bath at [[Aluminum Anodizing#Stripping Existing Anodize]] is the wrong tool here. Three real options, in order of preference: 1. **Polish it off.** The Ti oxide film is microns thin. Hit it with a Roloc disc, scotch-brite, or 1000-grit sandpaper and the color is gone in seconds. This is the standard fix for a botched anodize. 2. **Anodize over the top.** You can only go up in voltage. If you anodized to 30 V (dark blue) and wanted 70 V (pink), just ramp to 70 V and the color overwrites. This doesn't *strip* the oxide — it grows a thicker one over the existing one. Won't fix burned spots or contamination. 3. **HF-based etch (not recommended for hobby).** Whink, Kroll's reagent, and similar contain hydrofluoric acid. HF is in a different danger category — causes painless skin entry followed by delayed bone damage. **Do not use without 2.5% calcium gluconate gel on hand and an ER plan.** Mechanical polish is faster, safer, and works fine for hobby-scale parts. The kit's stainless cathode and titanium hanging wire don't need stripping between sessions — Ti doesn't carry color over to the next anodize, and the wire's color is irrelevant. # TODO - ==Verify garage outlet is GFCI — if not, get a plug-in GFCI adapter== - ==Sand a Ti scrap up through 800 / 1000 / 2000 grit to use as a voltage-color test strip — anodize one strip across 10–120 V in zones, label, photograph, keep as reference== - ==Order a niobium scrap for Nb color tests (different palette)== - ==Get a cheap multimeter to verify the power supply voltage matches the dial== - ==Decide where this goes in the garage — needs ventilation, GFCI, dry bench, away from the aluminum-anodize acid bath== - ==Print and laminate the Skellie color chart for the wall== # Build Log ## 2026-05-26 - Bought the [[Caswell Titanium & Niobium Anodizing Kit]] (TANKIT) - Created this note alongside [[Aluminum Anodizing]] from the official Caswell instructions + Brian Skellie's reference + the 2012 Caswell Plating Manual - Identified that the 2012 manual's color chart is incorrect and flagged it - Confirmed the kit includes its own 120 V / 1 A power supply — no separate rectifier purchase needed - ==Plan: run voltage-color test strip on a Ti scrap before any real part== # References - Caswell Plating Manual Version X (2012), p. 122 — "Titanium Anodizing — For reference only" (note: outdated and partially incorrect) - [Caswell Titanium & Niobium Anodizing Kit instructions PDF](https://emeraldcoatings.com/wp-content/uploads/2018/03/Titanium-Anodizing-Kit-Instructions-1.pdf) - [Brian Skellie — Anodization](https://brnskll.com/shares/anodizing/Anodization-c967106) — canonical reference for Ti/Nb anodizing - [MonsterBolts color chart 10–100 V](https://monsterbolts.com/pages/anodized-titanium-color-chart) - [TZR Metal — voltage control](https://tzrmetal.com/titanium-anodizing/) - [HonTitan voltage chart](https://hontitan.com/titanium-anodizing-guide-voltage-chart/) - [Multi-Etch — HF-free Ti etcher](https://www.multietch.com/blog/etching-safety-environmental-issues.html) - [Finishing.com — Ti anodizing with TSP](https://www.finishing.com/28/83.shtml) - [Spider Chain — All About Niobium](https://www.spiderchain.com/reference/all-about-niobium/) - [[Aluminum Anodizing]] — sister process note