Temperatures
Torch Fuel Characteristics and Temperatures |
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| Chemical Fuel | Formula | Special Characteristics | Flame Temp. w/Oxygen | Flame Temp. w/Air | BTU per lb. |
| Acetylene | C2H2 | Burns hottest; popular fuel gas; not recommended for use with platinum | 6300°F | 4217°F | 21,499 |
| Natural Gas | ** | Burns clean; economical to use | 4600°F | 3420°F | — |
| Propane | C3H8 | Burns clean; economical to use | 4780°F | 3497°F | 21,260 |
| Butane | C4H10 | Low heat; available in portable containers | 4995°F | 3443°F | 21,298 |
| Hydrogen | H2 | High heat; cleaner than acetylene | 4850°F | 3713°F | 61,085 |
| MAPP® | C3H4 | Somewhat concentrated high-temperature flame | 5300°F | 3600°F | 2300 |
** Typical analysis: methane 83.4%, ethane 15.8%, nitrogen 0.8%.
High Temperature Judged By Color |
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| °F | °C | Color |
| 752 | 400 | Red heat, visible in dark |
| 885 | 474 | Red heat, visible in twilight |
| 975 | 525 | Red heat, visible in daylight |
| 1077 | 581 | Red heat, visible in sunlight |
| 1292 | 700 | Dark red |
| 1472 | 800 | Dull cherry red |
| 1652 | 900 | Cherry red |
| 1832 | 1000 | Bright cherry red |
| 2012 | 1100 | Orange-red |
| 2192 | 1200 | Orange-yellow |
| 2372 | 1300 | Yellow-white |
| 2552 | 1400 | White welding heat |
| 2732 | 1500 | Brilliant white |
| 2912 | 1600 | Dazzling white, blue-white |
Annealing Temperature Guide
Time at the full annealing temperature will depend on the thickness of the section, but 1 minute per mm of section should be sufficient for thickness up to about 5 mm. Too frequent annealing or annealing for too long can cause grain growth which may make subsequent working or polishing to a smooth surface more difficult.
Specific Gravity and Metal Melting Points |
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| Metal | Melting Point °C | Melting Point °F | Specific | Metal | Melting Point °C |
Melting Point°F | Specific | |
| Aluminum | 660 | 1220 | 2.7 | Iridium | 2454 | 4450 | 22.5 | |
| Bronze | 1060 | 1945 | 8.8 | Iron | 1535 | 2793 | 7.9 | |
| Copper | 1083 | 1981 | 8.9 | Lead | 327 | 621 | 11.3 | |
| Gold (fine) | 1063 | 1945 | 19.3 | Nickel | 1455 | 2651 | 8.8 | |
| 22K Yellow | 977 | 1790 | 17.3 | Nickel Silver | 1110 | 2030 | 8.8 | |
| 22K Coin | 940 | 1724 | 17.2 | Palladium | 1549 | 2820 | 12.2 | |
| 18K Yellow | 1030 | 1885 | 15.5 | Platinum (Pure) | 1774 | 3225 | 21.4 | |
| 18K Green | 966 | 1770 | 15.6 | 5% Cobalt | 1765 | 3209 | 20.8 | |
| 18K Rose | 932 | 1710 | 15.5 | 5% Iridium | 1790 | 3254 | 21.4 | |
| 18K White | 940 | 1725 | 15.7 | 10% Iridium | 1800 | 3272 | 21.5 | |
| 14K Yellow | 960 | 1760 | 13.4 | 5% Ruthenium | 1795 | 3263 | 20.7 | |
| 14K Green | 835 | 1535 | 13.6 | Silver (Fine) | 961 | 1762 | 10.6 | |
| 14K Rose | 827 | 1520 | 13.4 | Sterling | 920 | 1640 | 10.4 | |
| 14K White | 975 | 1785 | 13.7 | Stainless Steel | 1371 | 2500 | 7.8 | |
| 10K Yellow | 980 | 1796 | 11.6 | Titanium | 1800 | 3272 | 4.5 | |
