Choosing the right size and kind of foil for your stained glass project can be a confusing task, due to the variety of sizes and backings. There are some general guidelines for selecting the right foil that can help eliminate some of the confusion.

The first consideration is the width of the foil. While skinny foil lines look nice, they are structurally weaker, since they allow less solder to be applied. 7/32" copper foil is a good general size for most projects, but varying the width of foil used can draw the eye around a project, and add depth and emphasis to a project. On thicker glass 1/4" foil can be used to allow a normal width seam to be formed. For special effects, an Xacto or razor knife can be used to trim the copper foil once it has been applied to the glass. To achieve a look of distance, the foil lines should gradually get thinner as they recede into the distance. 3/16" or 5/32" copper foil can be used in moderation for detailed areas, but should generally be avoided for entire projects, as the ultra-thin solder lines that it produces are weaker than wider solder lines.

The next thing to consider is the thickness of the foil, which is measured in mils. 1 mil copper foil is ultra thin, and tears easily around curves. Because of that, it is not a good all-purpose thickness, as it can be cumbersome and frustrating to try and use it for an entire project. Additionally, since it tears frequently, you’ll find yourself having to patch the torn spaces, which is time-consuming and discouraging. 1.25 mil foil is a good choice for most projects, as it combines the needed flexibility for inside curves with the strength needed for secure projects. It can be applied easily without hurting your fingers, and won’t tear as easily as thinner foils. 1.5 mil foil is very stiff, and due to that stiffness, it can cut and hurt your fingers while applying it to the glass, but does a good job of providing a framework for the solder to adhere to.

The final consideration for choosing a type of copper foil for your project is the color of the backing. A general guideline for choosing the backing color is to consider the color that your project will be patinaed when finished. For projects that won’t have patina applied, silver back foil is a good fit, since the silver of the foil will complement the silver of the solder lines. Likewise, projects that will have copper or black patina applied will be complemented nicely by copper backed or black backed foil, respectively. The backing color is not as much of an issue when working with opalescent glass, since the color of the foil won’t be seen as noticeably through the edge of the glass. The backing color for transparent/cathedral glass is very important, as a mis-match can stand out noticeably. Choosing the right color of backing is a small, professional touch that distinguishes your work, and can separate you from the imported foreign work that is poorly constructed, and has little thought given to fine details.

We also recommend selecting a copper foil from a reputable manufacturer, like Edco or Venture. While there are cheaper foils available, the adhesive on them is often second rate, which means that it can be hard to keep them adhered to the glass long enough to solder the project. Additionally, the adhesive burns off quickly while soldering, making the foil peel and crinkle, which means your solder lines turn out lumpy and uneven looking.

We hope that this guide has given you the necessary information for choosing the right copper foil for your next stained glass project, and cleared up some of the mystery surrounding the variety of sizes, backings, and manufacturers from which to choose.

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Apex GlassWorks