FAQs

For dry powder, at least 11 years. For unused Multi-Etch in solution: at least two year (keep it capped)!

Approximately 5,000+ square inches of titanium when dipped for 7-10 seconds at 150-160ºF. As you etch, the etchant gradually becomes ineffective and saturated with titanium ions that can re-plate to the metal, causing uneven anodizing.

The short answer is that the etchant is still working if you’re able to get good color. If you are working on one-offs or something special it’s best to use fresh etchant. But if you need to etch with used etchant, first check for good color by etching and anodizing some titanium scrap of the same type/alloy as your workpiece. For more details, see our guide on keeping etch times consistent with Multi-Etch.

No, that’s why it’s best to use only as much as you need in any one sitting, leaving the rest unadulterated.

Use titanium or niobium wire bent around the piece to be anodized, or strung through a hole in the piece. 

You can also buy or make plastic holders. If making a basket be sure to drill holes in plastics marked 5 or marked 7. Affix a handle if you want or suspend the holder from a wire made of titanium or niobium.

This varies based on federal, state, and local wastewater regulations, but is generally much easier than disposing of hydrofluoric acid. Consult a wastewater expert where you live to determine what is allowed, or read our disposal page for details.

If there isn’t any change in color, check your connections. After using many techniques to anodize since the 1970s, sometimes we still get our wires crossed!

1. Did you mix the entire amount of Multi-Etch powder and let it sit overnight? The ingredients in Multi-Etch are not blended so you must mix the entire amount with 1/2 gallon of distilled or deionized water for double-strength or .968 gallon (15.5 cups, 3.667 liters) for regular strength.

2. If you want to use Multi-Etch at room temperature, it still needs to be heated one time. Mix with distilled or deionized water heated to 150-160ºF, shake or stir and let the solution sit overnight. Shake or stir again before using at room temperature, 70ºF.

3. Initially etching some scrap titanium can act as a catalyst to “wake up” Multi-Etch.

4. Make sure you have degreased the metal before etching. If the metal is particularly dirty, e.g., after tumbling, etch once, rinse well, and etch again. Hold the pieces by the edges so that you don’t leave fingerprints.

5. Did you accidentally contaminate your etching bath? If you introduce brass, copper or iron into the etching bath, those materials will tend to plate onto the titanium and interfere with anodizing. A pink cast to the etchant indicates iron or steel; blue would indicate copper. If that happens, you will need to discard your contaminated etching bath and start with a fresh one. These contaminants could come from the tooling you use to form your piece--files, saws, etc. If possible, keep a separate set of tools or clean the piece with an ultrasonic before etching.

6. What are you holding the titanium with while anodizing? Using something other than titanium, niobium, or plastic to hang or hold your work piece when anodizing can prevent the voltage getting to the titanium. Some metals, such as copper, brass, gold, etc. will draw off the voltage. You can also use a plastic container with a titanium or niobium probe to anodize--this works great for anodizing lots of small parts.

7. Make sure you rinse well after etching the metal. If you drag Multi-Etch into your anodizing bath, it can inhibit good color. If you are not going to anodize immediately after etching, protect the clean surface by applying a 10-volt color. If you don’t want to anodize at all, then store the etched pieces in distilled water. This will allow you to wait months if necessary, before anodizing.

8. What alloy and form of titanium are you using? Sometimes the ends of a batch of wire or sheet have a heat oxide that is very hard to remove. You also can’t see it! But if you suspect that might be the problem because most of the pieces in a batch anodize fine, try etching the “bad” pieces longer and avoid using the high-voltage colors if possible. 

9. Cast titanium parts like medical implants sometimes have a whitish alpha-case from heat which must be mechanically removed (e.g., sand-blasting or wire brushing.) If this is not removed, it may be difficult or impossible to anodize evenly with higher voltage colors. Try etching longer before anodizing.

10. Grow the oxide slowly. If you’re aiming for the color at 70 volts, ramp the voltage to 60 and, while leaving the piece in your anodizing bath, keep the voltage at 60 and see if the color continues to advance to the higher voltage color. If it doesn’t, try increasing the voltage slowly.

11. What is your anodizing solution? We recommend either 4 ounces of TSP or 2 ounces of ammonium sulfate per gallon of distilled water. If the anodizing reaction is too slow, add a little more TSP or ammonium sulfate. With either type of anodizing bath, you can squirt a little dish detergent or Simple Green to act as a surfactant, which is important when you are after a smooth gradation from one color to another. Without that, sometimes the liquid “beads up” when lifting the titanium out of the bath.

12. It’s possible that if you purchased distilled water in a plastic jug that has   been sitting around the store awhile, the water may have absorbed something from the plastic jug itself. Try using water from a purified water vending machine.

13. Poor color can be a sign that you haven’t etched long enough or you have used up the etchant and need to replace the bath.

14. If you wire-brushed or used other steel tools, make sure you have thoroughly cleaned any contaminants from the titanium before etching.

Sometimes everything is “correct” but you still can’t get even color in the higher voltages. This can be due to inconsistencies on the metal itself. High-voltage colors are the hardest colors to achieve so if you have a choice, choose a lower voltage color, especially for the problem pieces.

If you discover something not covered here, please let us know! info@multietch.com