By Joe Wagner | Photos by Allison LegerAs seen in the September 2009 issue of Model Aviation.THIS ARTICLE WILL cover soft soldering. That’s done with solders that melt at relatively low temperatures—lower than 500 degrees Fahrenheit. Some confusion about solder terminology arose when lead-free solders containing approximately 95% tin and 5% silver became standard in applications such as installing soldered-together copper-tube plumbing. That mixture was federally mandated, to prevent lead contamination of drinking water.Some plumbers mistakenly called the new material “silver solders”;…