Choosing the right solder is critical to the success, safety, and longevity of your project. Whether you’re tackling a plumbing job, an electrical repair, or a specialty metalworking task, the solder type used matters.
In this guide, we'll break down the different types of solder, their compositions, applications, and how to pick the right one.
Lead-Free vs. Leaded Solder
Solder is a metal or metallic alloy that historically consisted of lead and tin in various proportions. Today, lead-free solder is available to comply with the Safe Drinking Water Act (SDWA), which restricts the amount of lead used in portable water systems.
Lead-Free Solder
Required by code for potable water systems, lead-free solder is safe for drinking water applications.
Oatey offers several lead-free options:
- Safe-Flo® Lead-Free Solder: This silver-based solder has a lower melting range (420–460°F), ideal for DIYers and professionals alike. The lower temperature minimizes the risk of burning off flux. That is especially helpful for those new to soldering.
- 95/5 Solder (Tin/Antimony): 95% tin and 5% antimony, designed as a lead-free alternative with a higher melting point (450°F to 464°F), it is commonly used for copper and brass in potable water lines.
- 97/3 Solder (Tin/Copper): This solder is preferred in certain regions, especially the Southern United States. Though functionally similar to 95/5, some local codes and contractor preferences may dictate its use.
Lead-free options were developed to mimic the flow characteristics of leaded solder while eliminating health risks. The closer a solder’s melting point is to 360°F, the easier it is to work with. Safe-Flo® was specifically formulated with this in mind.
Tin is the primary metal used in most solders because it melts at a relatively low temperature for a metal, around 450°F. Historically, tin was added to lead to improve solder durability. While lead melts at an even lower temperature, it is soft and prone to creep over time. The addition of tin made the material tougher and more rigid, making it ideal for structural bonds.
As plumbing moved away from lead-based solders due to health concerns, tin remained the base material. Its ability to melt low, alloy with other metals (like silver, copper, antimony, and bismuth), and flow well made it the perfect foundation for lead-free solder formulations.
Leaded Solder
Leaded solder, such as traditional 50/50 tin-lead blends, flows easily and melts at low temperatures, making it very user-friendly. As noted, because of its toxicity, it is not approved for use in drinking water systems, but it is still used in non-potable applications such as:
- HVAC heating systems
- Copper DWV (drain, waste, vent) lines
- Sheet metal and radiator work
Always check local codes before using.
Plumbing Solder Types
Here’s a breakdown of Oatey’s most common plumbing solders, all of which are lead-free and compliant with NSF 61 standards:
| Solder Type | Metal Composition | Melting Range (°F) | Features | Applications |
|---|---|---|---|---|
| 95/5 Solder | 95% tin / 5% antimony | 450°F–464°F | Tight melting range; designed for environments with extreme temperature changes and vibrations. | For drinking/potable water applications, refrigeration lines, and cooling equipment |
| 97/3 Solder | 97% tin / 3% copper | 440°F–572°F | Widest melting range; good for filling large gaps; commodity-grade | Potable water applications. Perfect for the sweating of copper and brass plumbing joints. |
| Safe-Flo | Tin, Copper, Bismuth, Silver | 420°F–460°F | Lowest melt start; premium performance and flow characteristics. Copper, bismuth, tin and silver alloy provide a low melting point | Copper plumbing, potable water line applications, brass or chrome alloys, galvanized steel and cast iron piping. Not recommended for use on aluminum |
| Instant Solder | Tin, Copper, Bismuth, Silver | 420°F-455°F | Specially formulated solder and flux in one; designed for applying small amounts of solder to a specific area | Repairing single joints in residential applications and hobby or craft work |
Melting Range and Flow Characteristics
From a plumbing perspective, the key differences between 95/5, 97/3, and Safe-Flo®/Silver solder come down to their melting range and how soon they begin to melt:
- 95/5 has the narrowest range and doesn’t start melting until 450°F, making it predictable and solid for everyday plumbing use.
- 97/3 starts melting around 440°F but has the broadest range, which gives it more “hang time” while soldering—ideal for larger pipe diameters or slower-heat applications.
- Safe-Flo®/Silver Solder begins melting as low as 420°F, offering the best flow characteristics and wider working range. It is especially helpful for newer users or for quick, clean joints.
Electrical Solder vs. Plumbing Solder
While electrical and plumbing solders bond metal components, they are engineered for very different environments and should not be used interchangeably.
Electrical solder is typically used to connect wires and electronic components. It often comes with a rosin core,meaning rosin flux is embedded within the solder wire. Rosin flux is noncorrosive, making it safe for delicate circuitry without damaging electrical components.
Some electrical solders also contain lead, which helps them melt at lower temperatures and flow smoothly. This is an advantage in electronics, but a liability in potable water systems.
Acid core solder is suitable for sheet metal or radiator repair where strong etching action is needed. Acid flux is corrosive and would degrade electrical parts.
In contrast, plumbing solder is designed to handle the mechanical stress and pressure of water lines. It is lead-free to meet safety and code requirements (NSF 61 certified) and is applied with a separate plumbing flux rather than a flux core.
Read this guide to choose the best plumbing flux for soldering copper pipes.
Note: It’s critical not to use electrical solder for plumbing. Even if the alloy seems similar, electrical solders are not approved for drinking water use.
Specialty Solder Types
From tin plating and seaming joints to fine electrical wiring, Oatey specialty or general-purpose solders are crafted to deliver maximum bond strength in electronic applications and sheet metal repair. When working on electrical wiring, choosing a solder appropriate for the specific electrical application is crucial.
Here’s a breakdown of Oatey’s specialty solders:
| Specialty Solder Type | Composition | Flux Type | Applications |
|---|---|---|---|
| 95/5 Lead Free Rosin Core Wire Solder | Tin-antimony (95/5) | Rosin | Electrical use where a noncorrosive flux is needed. Ideal for general wiring tasks. Not suitable for plumbing or potable water. |
| Rosin Core Wire Solder | Tin-lead | Rosin | Electrical work, including wiring and fine electronics. Not suitable for plumbing or potable water. |
| 95/5 Lead Free Acid Core Wire Solder | Tin-antimony (95/5) | Acid | General-purpose soldering for sheet metal, galvanized gutters, and metal seam repairs. |
| Acid Core Wire Solder | Tin-lead | Acid | Radiator repair, metal seams, and galvanized gutter fixes. Not recommended for plumbing or electrical use due to corrosive flux. |
| Bar Solder | Tin-lead (50/50) | None | Legacy format for tin plating, ductwork seams, or lead joint restoration. |
How to Choose the Right Solder
Selecting the right solder depends entirely on your application. Whether you're working on potable water systems, electrical, HVAC repairs, or specialty metalwork, matching your solder to the job ensures code compliance, durability, and optimal performance.
| Application | Recommended Solder | Details |
|---|---|---|
| Plumbing / Potable Water | Oatey® Safe-Flo® Oatey® 95/5 Oatey® 97/3 |
All are 100% lead-free and certified safe for NSF 61 potable water systems. 97/3 offers a higher melting point and is ideal for copper and brass piping. |
| Galvanized Steel / Electrical | Oatey® Acid Core Wire Solder Oatey® Rosin Core Wire Solder |
Acid core is best for galvanized gutters and metal seams. Rosin core is designed for electrical work, with a noncorrosive built-in flux that won't damage wiring. |
| Tin Plating / Sheet Metal Repair | Oatey® Wire Solder Oatey® Bar Solder |
Used for tin plating, sheet metal repair, or lead joint restoration. |
| HVAC Systems | Leaded Solder (where permitted) | May be used in closed-loop heating systems with non-potable water. Always verify with local code requirements before using. |
| Crafting / Jewelry | Oatey® Instant Solder | Ideal for small-scale work where precision and quick application are key. Best for hobbyists and crafters. |
New to soldering? This introductory guide explains the basics: What soldering is, when and why to use it, and how to do it safely and effectively.
Learn More About Soldering
Now that you understand the types of solder and their uses, head over to our Step-by-Step Guide to Soldering Copper Pipes for expert instructions on creating secure, code-compliant joints.
Frequently Asked Questions
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What solder is safe for drinking water?
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Lead-free solders certified to NSF 61, such as Oatey® Safe-Flo®, Oatey® 95/5 and Oatey®97/3
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Can you use electrical solder for plumbing?
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No. Electrical solders are not approved for potable water and may contain corrosive fluxes unsuitable for plumbing.
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What’s the difference between 95/5 and Safe-Flo®?
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Safe-Flo® begins melting at a lower temperature and flows more easily, making it a premium lead-free soldercompared to 95/5 or 97/3, which are more commodity-grade.
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