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| ==Procedure== | | ==Procedure== |
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| Use a copper wire thick enough not to melt too quickly (e.g., I2- or 14-gauge copper wire, stripped of its insulation, that is used for wiring houses). Heat the copper wire to glowing red in the flame of a Bunsen burner or propane torch.
| | You will need: |
| | * Thick copper wire (A tube of these is in the Trotec PC drawer) |
| | * Pliers |
| | * Propane torch (Usually found in the welding area) |
| | * A small sample of your material |
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| Continue heating until no colour (other than the nearly invisible, slightly blue torch flame) is visible. There should be no green colour in the flame. Wash the wire intermittently with water and dilute nitric acid (10%) to remove materials that cause unwanted colouration. If washing fails, try a new wire. Once it is clean, take care to avoid touching the wire with fingers or objects other than the test material. When the flame is colourless, the test can proceed.
| | Use a pair of pliers to hold the end of the wire in the flame for a few seconds |
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| The test is best carried out in subdued lighting so that the colour of the flame can be seen easily. Vapours, fumes, or smoke from the sample must envelop the hot copper wire in the flame so that reactions between the tested material and the hot copper can occur. This can be accomplished in several ways:
| | Stab the still-hot wire into a sample of your test material - try to get a decent amount of it melted on there |
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| # Heat the wire to red-hot, then quickly touch a fragment of the sample to it and immediately return the wire to the flame. A plume of green is a positive test for the presence of chlorine. Do not touch the entire sample with the hot wire. Some plastics (e.g., cellulose nitrate, Celluloid) may burst into flame. (This reaction is usually considered a positive test for cellulose nitrate.)
| | Put the wire back in the flame |
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| # With the wire red-hot and still at the edge of the flame, bring a fragment of the sample near the flame in the vicinity of the wire until the fragment chars and the smoke produced envelops the wire. A green flame is a positive test for the presence of chlorine.
| | If the flame emerald green, chlorine is present in the material and it must not be used in the laser cutter. |
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| # With the red-hot wire in the flame, place a fragment of the sample near or into the flame until it starts to char. Quickly move the smoking sample to the air intake at the base of the burner so that the smoke is drawn in with air and is intimately mixed with the flame gases. A green flame surrounding the copper wire is a positive test for chlorine.
| | If the flame remains blue or orange your sample does not have |
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| # Heat the wire to red-hot. Then immediately touch the wire with a piece of the sample held beside the air intake at the base of the burner or torch, so that some of the fumes produced are drawn into the flame. A green flame is a positive test for chlorine.
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| The fourth method described is the most sensitive. It is also the best method to detect the presence of a volatile chlorinated material — perhaps a solvent such as methylene chloride.
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| ==Discussion== | | ==Discussion== |