---
product_id: 21948511
title: "Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy, 0.031\" Diameter"
brand: "kester"
price: "$152.77"
currency: USD
in_stock: true
reviews_count: 3
category: "Kester"
url: https://www.desertcart.ec/products/21948511-kester-24-6337-0027-solder-roll-core-size-66-63
store_origin: EC
region: Ecuador
---

# 63/37 eutectic alloy for perfect melt 0.031" diameter ideal for 28-12 AWG cables Economy-sized 1 lb spool for long-lasting use Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy, 0.031" Diameter

**Brand:** kester
**Price:** $152.77
**Availability:** ✅ In Stock

## Summary

> 🔥 Melt like a pro, solder like a boss! 🛠️

## Quick Answers

- **What is this?** Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy, 0.031" Diameter by kester
- **How much does it cost?** $152.77 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ec](https://www.desertcart.ec/products/21948511-kester-24-6337-0027-solder-roll-core-size-66-63)

## Best For

- kester enthusiasts

## Why This Product

- Trusted kester brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Bulk Economy Spool:** Generous 1 lb roll designed to keep your projects flowing without constant reordering—because downtime kills momentum.
- • **Versatile Diameter:** 0.031" thickness strikes the perfect balance for soldering everything from delicate circuit boards to robust cable harnesses.
- • **Trusted Brand Legacy:** Kester’s proven quality since 2009 means you’re investing in a product favored by pros and hobbyists alike.
- • **Precision Eutectic Alloy:** 63% tin and 37% lead ratio ensures instant liquefaction and flawless flow—no messy globs, just shiny, reliable joints.
- • **Optimized for Reliability:** Achieve strong, heat-resistant connections that stand the test of time and current—don’t settle for subpar solder risking your builds.

## Overview

Kester 24-6337-0027 is a premium 1 lb spool of 63/37 tin-lead eutectic solder with a 0.031" diameter core, engineered for flawless melting and superior electrical connections. Ideal for a wide range of cable gauges and circuit board applications, this trusted solder roll delivers professional-grade performance and durability favored by electronics enthusiasts and professionals since 2009.

## Description

Sn63PB37 3.3% 66/44 .031 diameter

Review: Good solder! Buy some! - Great product for RC modelers and electronics hobbyists. This is a good value in a big, economy-sized spool which should last me a year or two. A dispenser is a good idea; this roll is much heavier than a standard hardware store pack and can be hard to manage. Mine likes to jump off of my table and go for a joy ride at the most inconvenient times, rolling across the room trailing wire. I guess another option would be to transfer some to a smaller spool as you use it. This .031" diameter is a pretty good compromise size for cables ranging from 28 to 12 AWG. It will even work on fairly roomy circuit board pads; however, I generally keep a small supply of thinner-diameter solder on hand for that kind of work. When I started out soldering cable harnesses, connectors etc. for my models, I found it pretty frustrating. As we know, the goal is to get the solder nicely liquefied so it will flow freely through the work, then keep things very still while it cools and solidifies. I found that, as I heated the cable and applied solder, it tended to soften, but getting it to melt completely enough to flow into the twisted wires - especially on bigger cables - wasn't easy. Instead I'd get a mushy glob that would sit on the surface without making good penetration. Then, when I was ready to let it cool, it seemed to take forever to solidify, making it hard to keep everything steady. As tempting as it may be, in such cases, to just stick the ends of the wires into a nice big glob of half-melted solder, let that cool and hide the pathetic result under a wad of electrical tape, the end product will NOT be a strong, reliable connection, able to withstand the necessary current without heating up, and may fail completely. Ask me how I know! Well, it turns out that the answer is in the choice of solder. For some reason, none of the instructional materials I studied early on even mentioned one of the keys to happy, safe soldering work. It lies in the concept of a "eutectic" mixture or alloy. For any combination of two or more metals, there is a certain ratio between the amounts of each which, when combined, yields an alloy with the lowest melting point possible. In the case of lead and tin, an alloy commonly used for electrical soldering, that ratio is 63 lead and 37 tin. That's the ratio used in this solder. The practical result, and the reason why a eutectic solder mix works so well, is that when it melts, it goes directly from the solid to the liquid state or "phase". When it cools and solidifies, it does the opposite. The intermediate state, known in technical terms as a "glob", is completely skipped! When it gets hot enough, whoosh! It instantly liquifies, and flows beautifully into the cable ends and/or onto the connectors. (Remember to always heat the cable or connector first, and let it heat the solder!). Remove the heat, maybe blow on it gently for a second, and whoosh! It's back to a nice, shiny (which is what you want) solid. A strong, reliable electrical connection is born. Just try it, you'll like it. Unfortunately, if you look at the labels of the majority of solders sold in hardware stores, you'll find that the lead/tin ratios are 60-40, not the "magic" 63-37. I have no idea why the 60-40 is even made, though if I had to guess, it may be because the "glob" state is desirable for certain types of users - plumbers, for example, or lazy electricians who prefer the "stick wires ends in glob" method described above. Just don't be that guy/gal, unless your fire insurance is paid up, and you're ok with watching smoke pour out of your electric model aircraft in the seconds before impact.
Review: Great solder!.. And some tips. - I've been soldering off and on since I was 8 years old, and son to an electrical engineer, and now I'm one myself. So I feel qualified to review solder. Firstly, when looking to purchase solder for your electronic projects you want to make sure your solder meets the following criteria: - If using lead based you want either 63/37 or 60/40 for a nice even melt - A flux core or multiple flux cores - A quality brand (Kester, Multicore, etc) You want to avoid the "Won-Hung-Lo" discount brands and bite the bullet and invest into a quality solder product. Your solder joints should be shiny and silver in color. If your solder joints are dull and grey or off silver or pitted.. You are using the wrong solder. I recommend Kester or Multicore solder as they are both consistent performers and both are quality products. I also highly recommend a good temperature controlled soldering iron. It doesn't matter if it's analog or digital but don't skimp on your iron either (Hakko or Weller, and not the type you plug directly into the wall). This particular thickness of solder is suitable to thru-hole and large component soldering. However if you intend to solder surface mount you will want a smaller thickness of solder anything .020 or less is more suited to SMD (or solder paste and a heat gun). You won't be disappointed with the quality of the Kester solder products.

## Features

- Country Of Origin: China
- Model Number: 24-6337-0027
- Item Package Dimension: 2.49999999745" L x 2.299999997654" W x 2.299999997654" H
- Item Package Weight: 1.0405 lb

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0149K4JTY |
| Best Sellers Rank | #26,607 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #74 in Solder |
| Date First Available | August 31, 2009 |
| Is Discontinued By Manufacturer | No |
| Item Weight | 0.7 ounces |
| Item model number | 24-6337-0027 |
| Manufacturer | Kester |
| Product Dimensions | 2.5 x 2.5 x 3 inches |

## Images

![Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy, 0.031" Diameter - Image 1](https://m.media-amazon.com/images/I/21sM03k6keL.jpg)
![Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy, 0.031" Diameter - Image 2](https://m.media-amazon.com/images/I/51+2ulD2A6L.jpg)
![Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy, 0.031" Diameter - Image 3](https://m.media-amazon.com/images/I/71fkT7fe0kL.jpg)

## Questions & Answers

**Q: I need some solder for r/c car battery wires and connectors. 10,12 and 14g wires to posts. Also smaller 22g wires to each other.**
A: I have been working in the electronic manufacturing and repair industry for over 50 years, here are my views:Kester 44 Activated Rosin Core Solder 63/37 (63% tin/37% lead) in .031 inch diameter is the best solder for most all around electronics work. The ratio of 63/37 gives this solder the lowest melting point of all other tin/lead alloys. This allows you to get on the connection, heat it up, solder it quickly and be done without having to heat up the wires and connections way too much. If you need a thicker solder you can look for it in .062 diameter or even .125 diameter. The thicker diameters are good for soldering larger connections (like a 10 or 12 guage wiring points). You can also twist together two or three smaller diameter solder wires to make a thicker solder if you need too. You can get all kinds of these solders at your local radio scrap store in 63/37 and 60/40 ratios, but the impurities in that cheaper solder could make your soldering job a bit more difficult. Also the fluxes that are used in other solders might not work as well as the Kester brand. All of these solders are available in smaller quantities, you shouldn't need a full pound roll unless you are doing a LOT of R/C work. A few things to remember: It is difficullt to make a good solder connection if your iron is not hot enough or if it does not have enough thermal mass to transfer the heat quickly. Best to use a hot iron of 60 to 80 watts so that you can do the soldering quickly. Do not use acid core solder or acid fluxes for electronics work, the leftover acid can can be conductive and can cause electrical leakage and corrosion.There are "No Lead" solders available, but they require more heat to make a good connection. As a beginner, it might be best to use the tin/lead alloy solder and just remember not to eat the solder and not to lick your hands while you are working. Then wash up after your soldering session.For a good solder connection, follow these steps:1. Position your work such that nothing can move while you are soldering the joint.2. Make sure your iron is at full heat and that it is tinned with fresh and shining solder.3. Put the soldering iron tip on the joint.4. Immediately, put the solder wire at a point where it is touching the joint and the soldering iron tip.      (This will allow a thermal bridge to be formed between the tip and the joint)5. Now hold both the solder iron and the solder on the joint and when it gets up to temperature, the solder will melt.6. Feed solder into the joint until it is filled and fully wetted.7. Back off.8. Let the solder joint cool without moving anything.9. Inspect the joint. 10.  It should be shiney and solid with no cracks or crystallized areas.Hope this helps  :)xJoe

**Q: Will I need additional Flux, when using this solder ?**
A: No additional flux is normally needed when using Kester 44 Rosin Core solder for normal tasks such as soldering electronic through-hole components to the pads on a printed circuit board (PCB). The type "44" rosin flux itself is an internal part of the solder wire and it will wet, and clean, a metal-to-metal junction when the connection is heated and the tip of the solder wire is applied to the junction. After cooling, the rosin flux may be cleaned from soldered connections with isopropyl or rubbing alcohol and a cotton swab or a Q-tip.

**Q: What do 66 and 44 mean? Thousandths of an inch???**
A: Core Size / Flux % by weight

#05 0.50% 
#12 1.20% 
#22 2.20% 
#28 2.80% 
#30 3.00% 
#40 0.60% 
#45 4.50% 
#50 1.10% 
#58 2.20% 
#60 6.00% 
#66 3.30% 
#70 4.40%

**Q: What % is the rosin core, 2% 3%?**
A: Kester Solder designates the number "66" to describe the core size of this solder. "66" core is 3.3%.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Good solder! Buy some!
*by K***R on December 7, 2014*

Great product for RC modelers and electronics hobbyists. This is a good value in a big, economy-sized spool which should last me a year or two. A dispenser is a good idea; this roll is much heavier than a standard hardware store pack and can be hard to manage. Mine likes to jump off of my table and go for a joy ride at the most inconvenient times, rolling across the room trailing wire. I guess another option would be to transfer some to a smaller spool as you use it. This .031" diameter is a pretty good compromise size for cables ranging from 28 to 12 AWG. It will even work on fairly roomy circuit board pads; however, I generally keep a small supply of thinner-diameter solder on hand for that kind of work. When I started out soldering cable harnesses, connectors etc. for my models, I found it pretty frustrating. As we know, the goal is to get the solder nicely liquefied so it will flow freely through the work, then keep things very still while it cools and solidifies. I found that, as I heated the cable and applied solder, it tended to soften, but getting it to melt completely enough to flow into the twisted wires - especially on bigger cables - wasn't easy. Instead I'd get a mushy glob that would sit on the surface without making good penetration. Then, when I was ready to let it cool, it seemed to take forever to solidify, making it hard to keep everything steady. As tempting as it may be, in such cases, to just stick the ends of the wires into a nice big glob of half-melted solder, let that cool and hide the pathetic result under a wad of electrical tape, the end product will NOT be a strong, reliable connection, able to withstand the necessary current without heating up, and may fail completely. Ask me how I know! Well, it turns out that the answer is in the choice of solder. For some reason, none of the instructional materials I studied early on even mentioned one of the keys to happy, safe soldering work. It lies in the concept of a "eutectic" mixture or alloy. For any combination of two or more metals, there is a certain ratio between the amounts of each which, when combined, yields an alloy with the lowest melting point possible. In the case of lead and tin, an alloy commonly used for electrical soldering, that ratio is 63 lead and 37 tin. That's the ratio used in this solder. The practical result, and the reason why a eutectic solder mix works so well, is that when it melts, it goes directly from the solid to the liquid state or "phase". When it cools and solidifies, it does the opposite. The intermediate state, known in technical terms as a "glob", is completely skipped! When it gets hot enough, whoosh! It instantly liquifies, and flows beautifully into the cable ends and/or onto the connectors. (Remember to always heat the cable or connector first, and let it heat the solder!). Remove the heat, maybe blow on it gently for a second, and whoosh! It's back to a nice, shiny (which is what you want) solid. A strong, reliable electrical connection is born. Just try it, you'll like it. Unfortunately, if you look at the labels of the majority of solders sold in hardware stores, you'll find that the lead/tin ratios are 60-40, not the "magic" 63-37. I have no idea why the 60-40 is even made, though if I had to guess, it may be because the "glob" state is desirable for certain types of users - plumbers, for example, or lazy electricians who prefer the "stick wires ends in glob" method described above. Just don't be that guy/gal, unless your fire insurance is paid up, and you're ok with watching smoke pour out of your electric model aircraft in the seconds before impact.

### ⭐⭐⭐⭐⭐ Great solder!.. And some tips.
*by J***P on December 7, 2014*

I've been soldering off and on since I was 8 years old, and son to an electrical engineer, and now I'm one myself. So I feel qualified to review solder. Firstly, when looking to purchase solder for your electronic projects you want to make sure your solder meets the following criteria: - If using lead based you want either 63/37 or 60/40 for a nice even melt - A flux core or multiple flux cores - A quality brand (Kester, Multicore, etc) You want to avoid the "Won-Hung-Lo" discount brands and bite the bullet and invest into a quality solder product. Your solder joints should be shiny and silver in color. If your solder joints are dull and grey or off silver or pitted.. You are using the wrong solder. I recommend Kester or Multicore solder as they are both consistent performers and both are quality products. I also highly recommend a good temperature controlled soldering iron. It doesn't matter if it's analog or digital but don't skimp on your iron either (Hakko or Weller, and not the type you plug directly into the wall). This particular thickness of solder is suitable to thru-hole and large component soldering. However if you intend to solder surface mount you will want a smaller thickness of solder anything .020 or less is more suited to SMD (or solder paste and a heat gun). You won't be disappointed with the quality of the Kester solder products.

### ⭐⭐⭐⭐⭐ Plumbum.... A "other Metal" by any other name would smell just as sweet.
*by S***E on June 10, 2014*

Have you ever wanted to solder micro PCB transistors and resistors like a demi god/ robot? Then this solder is for you. Do you want a lead solder with a competent flux that will bond your connections like a champ, and give off fumes with the sweet taste of Bismuth salts and antimony that pairs nicely with a glass of Montepulciano or a Sanghiovese? Then this flux core is for you. Do you want to live as long as possible and keep your sperm count up? Then maybe you'd prefer a Rohs solder, and after throwing it across the room you'll realize: laboratories and electronics are not for you. We all die sometime, we're surrounded by death. No need for the constant reminder from our electronic devices that die before their time, due to inferior Rohs compliant solders. Women like mysterious dangerous men, and what could be more dangerous than a man who breathes fire and lead fumes? Nothing. Take it from me: a scientist; put a roll of this bad boy in your laboratory and watch the panties drop. Now I know what you're thinking: "we have a disparity in the sciences, with too few women taking degrees in the hard sciences thanks to years of uninformed dogmatic gender role ascribing women to careers other than the hard sciences. Now we're paying the price. Do you realize how hard it is to get a lady in your laboratory?" Well, true. And no. I don't. because I use spools of lead solder. Fact: women are drawn to the sweet smell of Bismuth salts and the pheromones excreted by a man with acute lead toxicity coursing through his veins are unmistakably unique. It intoxicates their senses, they're drawn on a genetic level to procreate with you *immediately* because, with lead, there might not be much more time. Pretty sure Darwin mentions the mechanics of this exact biological drive in his work "The Expression of the Emotions in Man and Animals" but I wouldn't know. I'm a real scientist, not a biologist so I've not the time to read such quackery. What I do know about women I've learned from observation and captain Kirk. From observation I can assure you, heat up some of this solder, sit back and watch the women come in droves. Your lab will make Hugh's house look an all boy's academy. Hang another roll from your review mirror. Trust me. This solder will save us from the gender disparity in the sciences. It will save future generations. But, don't wait, copulate. After all, it is lead bearing solder, so there's not much time. I will continue to buy this solder.

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*Product available on Desertcart Ecuador*
*Store origin: EC*
*Last updated: 2026-02-01*