Generally speaking, solder is an alloy which contains tin and lead in varying proportions, occasionally with flux mixed in. While solder has a wide range of commercial and recreational applications, the solder bar stock we sell here is primarily used for sheet metal roofers to create watertight, weatherproof seams and joints, especially in hard to reach places.
Where two panels of sheet metal come together, one of the ways to join them is with a seam, for which we sell specialized tools, tongs, pliers and other seaming tools. However, in order to create a stronger bond between the panels and to shut out water and the other contaminants born by runoff, sheet metal roofers often complete the seam with solder.
A Solder Bar: What Properties It Needs
Depending on your intended uses for the solder bar stock, it may require a large range of mechanical and chemical properties. For example, electricians using solder to make connections must use a solder with high electrical conductivity. Plumbers may prefer to use tin-silver or pure tin solder, to avoid incidental contact with drinking water and the solder.
For sheet metal roofers, bar solder is typically available in a mix of tin and lead; solder used by sheet metal roofers should be strong yet somewhat flexible, be able to bond chemically to the substrate (the sheet metal panel), and have both a low melting point and desirable properties upon resolidification.
Because of this wide range of properties, there are solder mixtures available that contain a wide range of different metals, including aluminum, zinc, cadmium, copper and even bismuth in addition to the lead, tin and silver mentioned so far in this article.
But as far as roofing solder or general purpose solder is concerned, and given the well known status of lead as a toxin, why is lead often included in the formula?
Lead vs Tin
The solder we sell here is primarily composed of both lead and tin (although we also sell pure tin, lead-free solder) in varying amounts to provide a balance of benefits. For its part, tin has a lower melting point than lead, at a hair beneath 450 degrees Fahrenheit. Tin is also harder and stronger than lead; solder that contains higher proportions of tin are harder, stronger and easier to melt than solder with higher concentrations of lead.
It might seem as though tin has all of the advantages over lead, but this is not the case. Despite the fact that care must be taken in the presence of lead, and when handling it, it does offer a few unique benefits over tin, which allow the reasons for its inclusion in solder bar stock.
For one, lead is more flexible than tin, which can give a measure of durability to the joint that can’t be achieved using tin alone. Additionally, lead, which has a higher melting point and a higher specific heat than tin, releases heat much more slowly into the environment. As a result, it cools more slowly, and is less likely to stress during resolidification. Metals that cool too quickly may deform or develop thermal fractures as they resolidify.
Lead also is known to help discourage the formation of tin whiskers in tin-bearing solders, which are thin, wispy projections from the solder joint. Tin whiskers can form in the presence of electricity or compressive stress, but lead can help prevent them.
What We Offer
Most roofers use 50/50 tin/lead solder because typically roofs allow for lead-bearing solder compared to in-home solder jobs. Additionally, it’s easiest to work with as well as the most affordable of the varying types. 60/40 is also commonly used, though slightly harder to work with and slightly more expensive. Our tin-lead solders are made from virgin, pure materials and not from recycled tin or lead. Lead solder is well known for its ability to melt fluidly and resolidify nicely, and our high quality tin-lead solders will deliver on your expectations – just check our reviews on our product pages.
For roofers that have concerns associated with the use of lead solder, we offer pure tin solder, which is actually a eutectic mixture of 97% tin and 3% copper that produces no visible shrinkage during cooling and melts and resolidifies homogeneously.
Get the Rest of Your Soldering Essentials Here
In addition to the bar solder itself, we also carry soldering sets, boxes, flux, propane tanks and a wide range of soldering irons and iron tips for an equally wide range of applications. In addition to pointed soldering iron tips we also carry hatchet tips, hammer tips and chisel tips which are ideal for soldering long, straight lengths along flat seams.
Like all of the products we offer here at Stortz.com, our soldering iron, accessories and bar solder are produced to the highest possible standards of quality and intended to uphold those standards on the job. If you have questions about any of our products, please contact us at 888-847-3456.