Comparing solder cost

[BobPi]

I'm starting to spend more time doing glass, using what I make in the house. It's getting expensive. I expect the glass to be pricey, but so is everything else.

I know it's not my largest cost, but something I wonder about.  Especially after putting over $20 just in solder on a single panel.  Is solder sold specifically for stained glass worth the premium, or will any 60/40 solder do?

[Richard Gross]

The two paragraphs quoted below are from the SGAA Reference & Technical Maual, Second Editon. These paragraphs come from "Chapter 8, Glazing," and are part of an essay by Mark Talaba. The entire essay looks very closely at the performance of solder and is certainly worth reading if you'd like an in-depth understanding of solder in stained glass. Remember that the "seven cents per pound" number cited in the essay represents metal prices in the early '80s. 

b. Are There 'Good' and 'Bad' Solders?:
Solder composition and purity have a dramatic impact on working characteristics and bonding strength. For instance, as little as 1⁄10 of one percent of zinc or aluminum can have an adverse effect, and the presence of more than 1% of antimony, perfectly alright for most soldering, will cause excessive brittleness in solder joints made on zinc and brass. (Bargain-priced 'special alloy' solders usually contain about 1% to 2% antimony in a 50/50 substitute, and 2% to 3% in a 60/40 substitute.) Dross (dirt and oxides) is sometimes found in wire solder, appearing as small lumps, pits, or discolored areas. When melted, the dross floats up and interferes with the formation of a smooth joint or bead. This would tend to be an intermittent (infrequent) problem, however, not a persistent one.

Guidelines for solder purity and composition (Federal Specification QQS-571E) were established by the Defense Department to assure consistent quality and dependability in solder work done by, or for, the U.S. Government. These guidelines are stringent, and solder manufacturers generally do adhere to them in the interest of quality, though they are not legally bound to do so. It is interesting to note that the proportions of tin and lead listed on the label (unless marked 'Meets Fed. Spec. QQS-571E') are not necessarily present in the solder. Material has appeared on the market with a shortfall of as much as 8% of tin in '50/50' solder. Besides the substantial effect on the solder's working properties, each percentage point reduction in tin yields a savings to the manufacturer of about seven cents per pound, and a shortage of about three feet of 1⁄8" diameter wire per 25 pounds. Fortunately, most of the manufacturers supplying solder to the glassworking market are reputable and honest, so this type of unscrupulous price shaving is an exception. The nominal tin/lead percentage is usually accurate to within + 1%.

[BobPi]

Thanks for the response, Richard. I'll have to see how the other solders meet those specs, if that information can be obtained from the manufacturers. Otherwise, I guess it's just a matter of experience in the school of hard knocks. Fortunately, I don't expect much knocking into my glass, but with panels mounted into cabinet doors, ya never know.