How to Acid Etch Teflon
Teflon, or polytetrafluoroethylene (PTFE), is prized for its lack of friction and is present in everything from cookware to piping to arterial surgery. In addition to having a surface so slick that even geckos can't walk on it, PTFE is virtually inert; it has a low reactivity to nearly every chemical. While this makes Teflon resistant to corrosion, it also complicates matters when you are trying to bind PTFE to anything. Etching removes the fluorine atoms from PTFE and creates a carbon-based layer to increase its bondability and reduce its friction. However, etching solutions do pose certain health risks, so use the utmost caution when when handling these chemicals.
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Things You'll Need
- Protective goggles, mask, gloves, mask and clothing compliant with OSHA standards
- Well-ventilated room
- Oven
- Sodium naphthaline complex in 2-methoxyethyl ether etching solution (store at room temperature)
- Pot of water
- Heat source
- Glass thermometer
- Tall etching vessel/tank (polypropylene, polyethylene or stainless steel)
- 99.9% nitrogen gas
- 2 rinsing bins (polypropylene, polyethylene or stainless steel)
- Isopropyl or methyl alcohol
- Chlorine-free water
Instructions
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Wash the Teflon item thoroughly. Wipe dry. Bake in the oven until completely dry. Any foreign substance on the Teflon will prevent it from etching properly. Water in particular can interfere with the reactivity of the sodium naphthalene.
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Put on all protective gear. Place the closed container in a water bath and heat the sodium naphthalene solution to 131 to 149 degrees Fahrenheit. Open carefully with the spout pointing away from your face. Pour into the etching vessel. Add the nitrogen into the etching vessel as close to the etching solution as possible to create a barrier. This will prevent air from chemically bonding with the etching solution and reducing its effectiveness. Do not cover.
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Immerse the Teflon item in the etching solution. Sodium naphthalene solutions work best when used for full-immersion etching. Move the Teflon back and forth to ensure the etching solution moves over its entire surface. This is a self-limiting reaction, meaning the Teflon will not suffer any adverse effects if it is left in the solution. However, leaving it in for too long won't improve the etching process, so remove the Teflon after 30 to 60 seconds. Allow the etching solution to drain over the etching vessel, but do not allow it to dry.
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Place the Teflon in the first rinsing bin. Sodium napthalene in glycol ether is considered an environmental contaminant, so it should be contained rather than washed down the drain. Rinse the Teflon in isopropyl or methyl alcohol for five to 20 seconds. This will partially dissolve the naphthalene and deactivate the sodium.
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Heat the unchlorinated water to 158 degrees Fahrenheit. For best results, use distilled or deionized water. Chlorine can undo the etching to a certain degree. Rinse the Teflon in the water for 15 to 30 seconds.
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Air dry or bake dry at 158 to 176 degrees Fahrenheit until completely dry. Protect from ultraviolet light and humidity, which will decrease its ability to form bonds. The etched surface will retain its bonding properties for several months. However, its ability to bond may peak within the first 24 hours, so take advantage of that if you intend to bond it to anything.
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Dispose of the etching solution, alcohol and water. Disposal guidelines will vary depending on your state and county laws. However, this solution is not biodegradable and is considered an environmental contaminant, so do not wash it down the drain, bury it, pour it into a landfill or otherwise dispose of it in a way that promotes environmental contamination.
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Tips & Warnings
The sodium naphthalene solution should be dark green in color. Variations from this color will not etch properly.
Used solution may work for future etching projects, but store it in a separate container from the unused portion.
Research your state's requirements regarding the acquisition of the etching solution. It may be more cost-effective to purchase Teflon that has already been etched.
Prolonged inhalation of the sodium naphthalene solution may cause male and female reproductive disorders, irritation, dizziness, drowsiness, loss of coordination, headache, blurred vision, difficulty breathing, fatigue, nausea, stomach pain, vomiting, tremors, convulsions, loss of consciousness, cyanosis, respiratory failure, central nervous system depression, coma or death. Operate in a well-ventilated area and wear a protective mask at all times. Move into open, fresh air immediately if you experience any of these symptoms and seek immediate medical attention. Women of childbearing potential should not handle this substance, as it may cause birth defects.
Do not use if you are allergic to mothballs, as sodium naphthalene is the active ingredient in both mothballs and the etching solution.
In case of skin contact, wash immediately with cold water. Contact with skin may cause alkali burns or photosensitivity. Absorption through the skin may cause internal damage. Wash with soap and water and seek medical attention if irritation persists.
Contact with eyes may cause conjunctivitis, corneal damage, irritation, pain or eye opacity. Wash the eye for 15 minutes and seek immediate medical attention.
Ingesting the etching solution may irritate mouth, throat and digestive system. It may also depress the central nervous system or cause pain, headache, visual disturbances, salivation, diarrhea, dizziness and nausea. Seek immediate medical attention if ingested.
Do not allow the sodium naphthalene solution to overheat, as it has a flashpoint of 158 degrees Fahrenheit.
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