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SRA Solder 135 Rosin Paste Soldering Flux For Electronics, No Clean Flux Made for Lead and Lead-Free Solder Circuit Boards and Copper Electrical Wire - Safe Clean Residues with No Goopy Mess (2oz Jar)
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Purchase options and add-ons
- USA Quality Flux - Achieve the soldering results you desire with SRA 135. Our rosin paste flux is impurity free with superior solder flux paste wetting performance. Rosin flux soldering perfected.
- No Goop Solder Flux - Semi-solid solder wax consistency gives you superior control over application. Simply dip copper electric wires or apply electronic rosin flux to PCB and watch the solder flow!
- Electric Solder Flux - Unlike paste flux wax found at the hardware store, SRA 135 acid free electronics soldering flux is the safe and effective choice for electrical and electronic applications.
- Flux Specifications - 135 is a type RA (Rosen Activated) Flux with an Active Temp. Range of 93 – 315°C / 200 – 600°F. This listing is for one 2oz (56.6g) jar of electrical flux paste.
- Flux for soldering DIY electronics projects including Car Audio, Stereo & Hifi, Computers, RC Vehicles, Drones / FPV, Musical Instruments, Gaming Consoles, Model Railroad, Arduino / Raspberry Pi, etc.
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From the brand

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SRA Solder is a multi-generational family business located in Walpole, MA. Our story began in 1962 with Stan Rubinstein who started the company out of the basement of his home. For decades SRA focused on serving the booming jewelry industry of New England with high quality soldering wire, flux, solder paste, and dispensers. We have since expanded to a wide range of electronic soldering and test equipment to help you get the job done right.
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From the manufacturer



Appearance of the Flux
SRA #135 flux is an amber colored paste. The consistency of the flux should not be gooey or hard to puncture. In other words it should be solid but also easy to dip wires and applicators into. If you see crystallization (rosin hardening) at the surface of the flux this is absolutely normal and NOT an indication of expired or tampered with flux.
- SKU: FLS135
About
SRA #135 is a petrolatum-based soldering flux, containing Rosin and organic acid activator. Unlike many paste fluxes, it contains NO Zinc Chloride or Ammonium Chloride, making it ideal for electrical and electronic repairs. The Rosin also leaves a protective coating over the soldered area that can prevent corrosion.
- Ideal for electrical and PCB repairs
- Does not need to be cleaned
- Contains 2 ounces (56.6 grams) in a jar
- Type RA (Rosin-Activated) Flux
- Active Temperature Range: 93 – 315°C / 200 – 600°
- Dimensions: 2.5″ Dia x 1″ H (64 x 25.5 mm)
- Weight: 2.5 Oz (70.8g)
- Made in USA


Flux Comparison
Soldering without flux is like trying to put a new registration label onto your license plate without first wiping off the layer of dirt and grime that has accrued on your license plate since last year. The surface needs to be clean so the adhesives on the label can do their job.
Why Use Flux?
because solder cannot bond without it!
In order for solder to do its job, the layer of oxides on the metal surfaces you're soldering must be removed. A good flux, like #135, removes the oxides and sets the stage for soldering. The solder follows the flux, as if the flux were clearing a path for the solder and telling it where it to go. For many soldering applications, using only flux-core solder wire is sufficient. However, there are benefits of adding an externally applied flux such SRA #135, these benefits include:
- More control over where the solder will travel – Wherever you apply the flux, the solder will flow to.
- Expedites the soldering process – It takes less heat and time to get the solder to flow where you need it.
- Results in a stronger connection – The flux allows the solder to bond properly throughout the target area.
- Protects the solder joint – This rosin paste not have to be cleaned off after soldering and the residue actually provides a protective coating from corrosion.
How it Works
Prep Surfaces
Prep the surfaces by removing any dirt, rust, grease, paint, and other contaminants with sandpaper, wire brush, steel wool, etc. For many applications, the residues can be removed with just a rag and some isopropyl alcohol. These impurities may prevent solder flow so it is important not to proceed until clean metal is visible.
Choose an Applicator
Various tools can be used as an applicator for the flux including toothpicks, acid brushes and spatulas. Wires and components can simply be dipped as well. One of the benefits of paste flux opposed to liquid is that it will stay put wherever you apply it.
Apply the Flux Paste
Using your applicator of choice, apply the flux to the target areas you are about to solder. The exact amount applied will depend on the job but in general use just enough to cover the area to be soldered in an even coating. Remember that the solder will flow to where the flux is so make sure to apply only where it is needed to prevent solder bridges and mess.
Apply Heat and Solder
Apply heat using a soldering iron or hot air gun to bring to melting temperature and solder. Remove heat and allow to cool. Remove residue with rag if wanted.
Frequently Asked Questions (FAQs)
Is it effective when working to simply dip the solder wire into the flux and solder or is it significantly better to apply to the joint and why? You want to apply the right amount of flux. Too little and you won’t get good soldering results. Too much and you run the risk of the solder flowing where you don’t want it to, since solder follows flux. You want to apply the flux in the manner that will best ensure you lay down the right amount. Usually this means using a tool to apply the flux to the area being soldered and not dipping the part into the #135. SRA #135 is not runny, and if you dip the part into the flux, you might not get enough flux on it. That being said, I am sure there are people who do dip their part into the #135 flux and get good results.
Is it advisable to heat up the flux with a heat gun if it is too hard/solid? You would want to do this very carefully since you don’t want the ingredients in the flux to separate. Quick, intense heat could cause the flux to separate into disparate ingredients. While this is not too likely, it can happen.
If the rosin flux becomes dry is there anything you can do to return it to more of a paste? You would want to gently heat it until it softens up, but you need to be careful not to heat it up too quickly or at too high of a temperature.
Does dipping your soldering iron directly into the flux help keep the tip clean, are there any benefits? Not a great idea. It wouldn’t be good for the solder iron because if you get too much rosin on a solder iron, it can be hard to clean off. Also, it can cause the flux to separate. Better to put the flux on the part that you are soldering, and to then apply the solder wire and solder iron to the area where the flux is. Of course, the solder iron will usually contact the flux, but you don’t want to 'bathe' the soldering iron inside the flux by sticking it in the flux jar.
Product information
Technical Details
Manufacturer | SRA Soldering Products |
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Part Number | 135 |
Item Weight | 2 ounces |
Item model number | FLS135 |
Is Discontinued By Manufacturer | No |
Color | Rosin Paste |
Style | Rosin Flux |
Material | lead |
Item Package Quantity | 1 |
Cutting Diameter | 2.5 Inches |
Included Components | jar of flux |
Batteries Included? | No |
Batteries Required? | No |
Assembled Diameter | 2.5 Inches |
Additional Information
ASIN | B008ZIV85A |
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Customer Reviews |
4.7 out of 5 stars |
Best Sellers Rank |
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Date First Available | August 19, 2012 |
Warranty & Support
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SRA Solder 135 Rosin Paste Soldering Flux For Electronics, No Clean Flux Made for Lead and Lead-Free Solder Circuit Boards and Copper Electrical Wire - Safe Clean Residues with No Goopy Mess (2oz Jar)
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Product Description
This petroleum/rosin contains No Zinc chloride or ammonium chloride, making it a better choice for electronic repairs. Rosin leaves a protective coating over soldered area Once job is finished
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This Item SRA Soldering Products SRA Solder 135 Rosin Paste Soldering Flux For Electronics, No Clean Flux Made for Lead and Lead-Free Solder Circuit Boards and Copper Electrical Wire - Safe Clean Residues with No Goopy Mess (2oz Jar) | Recommendations | |||||
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Price | -23% $8.49$8.49 List: $10.99 | $14.95$14.95 | $5.99$5.99 | $5.99$5.99 | $8.49$8.49 | $6.99$6.99 |
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Customer Ratings | ||||||
Sold By | SRA Soldering Products | ZHUOBAO | JacobsParts | SZPLD | SRA Soldering Products | QUIMTECH ™ |
Customer reviews
Customer Reviews, including Product Star Ratings help customers to learn more about the product and decide whether it is the right product for them.
To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyzed reviews to verify trustworthiness.
Learn more how customers reviews work on AmazonCustomers say
Customers find the soldering flux works well, particularly for reheating old solder joints, and appreciate its excellent flow properties. The product is easy to use, especially for small projects, and customers consider it good value for money. Moreover, they praise its quality, noting it lasts a long time and produces great solder joints, while being easy to clean with isopropyl alcohol.
AI Generated from the text of customer reviews
Customers find that the soldering flux works well on electronics and is better than other products.
"...Also works great when reheating an old sloder joint to attach new wire to it." Read more
"Arrived in good condition, very useful.=" Read more
"...I want it so I’m more of a paste in a syringe guy but this stuff is still useful. It’ll last you a long time" Read more
"Its Flux, It works!" Read more
Customers find the soldering flux effective, noting that it helps solder flow perfectly.
"...Paste Soldering Flux makes soldering my circuit boards a breeze, flowing nicely with no messy residue...." Read more
"Its Flux, It works!" Read more
"My flux came inside the container and not stuck to the lid, for what that's worth!..." Read more
"...Well this time it flowed like it was supposed to, bonded cleanly, and in the end probably was my best work...." Read more
Customers find the soldering flux easy to apply, particularly for small projects, and one customer mentions it works well with a flat pick.
"...It’s easier to apply precisely and doesn’t require as much cleanup, which can make learning a lot less frustrating." Read more
"The SRA Solder 135 Rosin Paste Soldering Flux makes soldering my circuit boards a breeze, flowing nicely with no messy residue...." Read more
"Easy application, perfect consistency, fast working, and easy to clean. Reasonably priced and shipped fast." Read more
"I've only used this a little and very difficult to manipulate. Was told to add heat to soften so I'll try that next time." Read more
Customers find the soldering paste to be a good value for money, appreciating its quality and decent size.
"...Reasonably priced and shipped fast." Read more
"...It is a good amount for the price. If you like to do projects yourself this is a must have for your craft or tool box." Read more
"Is not the best but worth the money" Read more
"Only 6 or 8 $ but worth it in gold !!! High quality staff here. Yes . Buy it !!!" Read more
Customers find the soldering flux makes the process easier and more enjoyable, with one customer noting it's a time saver.
"Easy application, perfect consistency, fast working, and easy to clean. Reasonably priced and shipped fast." Read more
"A necessity for many soldering projects.." Read more
"This flux wax is perfect for soldering. I almost returned it after seeing more people use syringe flux, but I am glad I didn't...." Read more
"...I have to say it makes soldering a lot less frustrating, particularly if you were not that good at soldering to begin with...." Read more
Customers find the soldering flux to be of high quality, noting it will last for a long time. One customer mentions it stays solid at room temperature, while another notes it provides a lifetime supply for home amateur users.
"...The solder then is absorbed into the wire giving you a faster and stronger joint. Professional electricians use rosin paste regularly...." Read more
"Arrived in good condition, very useful.=" Read more
"...It’ll last you a long time" Read more
"Not bad for the price.!" Read more
Customers find the soldering flux easy to clean, requiring only isopropyl alcohol or a lint-free rag to remove excess.
"...It really helps ensure solid joints and clean work, especially when you’re dealing with dense boards or rework jobs...." Read more
"Easy application, perfect consistency, fast working, and easy to clean. Reasonably priced and shipped fast." Read more
"...just use flux paste when de-soldering, this paste works well and cleans up easily." Read more
"...The difference is amazing. Then just wipe the excess away and done. Much stronger stable joints" Read more
Customers report that the soldering flux produces great joints and improves soldering results, with one customer noting its effectiveness in delicate jobs.
"...It really helps ensure solid joints and clean work, especially when you’re dealing with dense boards or rework jobs...." Read more
"...will come with a rosin flux core, which is usually fine for basic soldering things together...." Read more
"This made my soldering a snap! I needed to tin a pot so the solder would stick and a tad bit of this did the trick!" Read more
"...Well this time it flowed like it was supposed to, bonded cleanly, and in the end probably was my best work...." Read more
Reviews with images

Good product
Top reviews from the United States
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- Reviewed in the United States on June 24, 2025Color: Rosin PasteVerified PurchaseThis flux is essential when you’re soldering and desoldering large amounts of ICs and chips. It really helps ensure solid joints and clean work, especially when you’re dealing with dense boards or rework jobs. That said, for beginners or those just getting into board repair, I’d recommend starting with a no-clean flux in a syringe. It’s easier to apply precisely and doesn’t require as much cleanup, which can make learning a lot less frustrating.
- Reviewed in the United States on May 20, 2025Color: Rosin PasteVerified PurchaseEvery person that solders repairing electronics experiences wire that is old, cheap and very little copper in it. When your trying to solder those kinds of wire youll spend time heating the wire and it will not accept solder! I use a wire brush or sandpaper to clean the wire ends then use a dab ot this rosin paste. The solder then is absorbed into the wire giving you a faster and stronger joint. Professional electricians use rosin paste regularly. It is the only way you'll get cheap solder to work. Also works great when reheating an old sloder joint to attach new wire to it.
- Reviewed in the United States on June 16, 2025Color: Rosin PasteVerified PurchaseDoes what is's designed to do.
- Reviewed in the United States on June 16, 2025Color: Rosin PasteVerified PurchaseHaven’t used that much yet but so far so good
- Reviewed in the United States on June 16, 2025Color: Rosin PasteVerified PurchaseArrived in good condition, very useful.=
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- Reviewed in the United States on May 16, 2025Color: Rosin PasteVerified PurchaseThe SRA Solder 135 Rosin Paste Soldering Flux makes soldering my circuit boards a breeze, flowing nicely with no messy residue. The 2oz jar is easy to dip into, but it can dry out if you don’t seal it tight after use.
Top reviews from other countries
- Sam huntReviewed in the United Kingdom on May 12, 2024
5.0 out of 5 stars Quality flux
Color: Rosin Flux - 2 PackVerified PurchaseThis is good flux
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Client d'AmazonReviewed in Canada on May 28, 2025
5.0 out of 5 stars excellent produit
Color: Rosin PasteVerified Purchaseexcellent produit comme dans la description.
- OrvilleReviewed in Australia on March 24, 2025
5.0 out of 5 stars Flux paste
Color: Rosin PasteVerified PurchaseFlux paste exactly as described, works as expected, fast postage.
- Roberto CuestaReviewed in Mexico on November 15, 2023
5.0 out of 5 stars Excelente
Color: Rosin PasteVerified PurchaseExcelente
- Joseph TanReviewed in Singapore on October 31, 2022
5.0 out of 5 stars SRA Soldering Products Rosin Paste Flux #135
Color: Rosin PasteVerified Purchasefast shipping, good packing and received in good condition, thank you!