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You can make a simple rosin soldering flux by dissolving pine resin or instrument rosin in ethanol or rubbing alcohol that is at least 80% alcohol by volume, then filtering and adjusting the liquid. The published recipe gives no measured resin-to-alcohol ratio, so treat the result as an experimental, highly flammable flux—not a standardized or independently tested formula.
What this homemade flux is—and what it is not
This is a rosin-based flux intended for soldering electronics. Its author, the Hackaday.io project account catsndogs, proposes pine resin or ready-made rosin sold for stringed-instrument bows as the rosin source. The project page was created on October 9, 2022, and Hackaday covered it on October 18, 2022. The project description is a hobby recipe, not a controlled formulation.
Hackaday describes it as “not ‘no clean’ flux.” Plan to clean its residue rather than leave it on a finished board. The project author says residue can be brushed off with alcohol, but neither that cleanup claim nor the author’s statements about solder compatibility come with a reported controlled trial. Hackaday’s article likewise does not establish measured joint strength or comparative performance.
Ingredients and supplies
- Pine resin, or ready-made instrument rosin.
- Ethanol or rubbing alcohol at 80% by volume or stronger.
- A coffee filter and a clean jar for straining and storage.
These are the materials named in the project recipe. It does not specify a fixed resin-to-solvent ratio, so there is no source-backed precise quantity to follow. Its “80vol% or stronger” alcohol guidance is the project author’s ingredient specification, not a laboratory result.
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- 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.
How to make the flux
- Put the rosin material in a suitable container and cover it with the alcohol. The project gives no measured quantities.
- Allow the rosin to dissolve. Do not heat the mixture: the author specifically warns that the ingredients are extremely flammable.
- Pour the liquid through a coffee filter into a clean jar to remove debris.
- Adjust thickness gradually: allow some alcohol to evaporate for a thicker mixture, or add more alcohol for a thinner one. The source gives qualitative guidance, not a target viscosity or a timed evaporation method.
Keep the mixture away from flames, sparks, and other ignition sources while preparing or handling it. The published instructions do not provide a storage-life, container-compatibility, or disposal specification.
Choosing a consistency for the job
The project author suggests a syrupier mixture for tacking small SMD components and a thinner one for hot-air soldering. This is qualitative advice, not a tested viscosity range or guarantee that the recipe suits a particular board, component, or soldering process. The author also says it works with leaded and lead-free solder; no comparative test results are reported.
Rank #2
- ENOUGHT QUANTITY: The package includes 2 jars of soldering flux. A total of 70 g. Enough quantity for your use.
- NON-CORROSIVE: Rosin is not conductive in dry conditions and has good insulation. Is not corrosive to metal substances such as circuit boards.
- OXIDATION RESISTANCE: Anti-oxidation effect on soldering iron head of gold-copper alloy substrate. Solder flux for semi-solid, not easy to dump.
- STRONG APPLICABILITY: Flux is suitable for welding instruments, gold, copper, tin, iron and other metals. Ideal for electronic welding, repair and rework.
- WHAT YOU GET: Rosin soldering flux paste * 2, our 7*24 friendly customer service for peace of mind.
Safety and cleanup
Both the project author and Hackaday emphasize the fire risk: the flux is extremely or very flammable. Do not heat it while dissolving the rosin, and keep it away from ignition sources. The project author recommends proper ventilation while soldering. “Natural” ingredients do not establish that the mixture or its soldering fumes are harmless; the cited sources provide no quantitative exposure assessment or product-specific health evaluation. A ventilation device is not, on the evidence available, a guarantee of safety.
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Because Hackaday explicitly says this is not no-clean flux, expect residue to require cleanup. The project author says to brush residue off with alcohol. That is the author’s guidance rather than independently verified cleaning advice, and the sources do not specify an alcohol concentration or a validated cleaning procedure.
Rank #3
- For electrical and electronic soldering applications
- Thermal stability enabling excellent wetting and reduced carbonization at soldering temperatures.
- Activity closely approaches that of fully activated rosins.
- Conforms to all of the requirements of Type RMA.
- Made in USA
What the recipe does not establish
- A repeatable measured formula: no resin-to-solvent ratio is stated.
- Performance relative to commercial flux, measured joint strength, or suitability for every electronics task.
- That the mixture is healthier, non-toxic, or safer than commercial flux. The “healthier” language is the project’s stated aim, not a substantiated conclusion.
- Emissions data, a quantitative safety assessment, or independent verification of the recipe’s claims.
Making this mixture can tell you which basic ingredients went into it, but ingredient transparency alone does not show that a flux is safer or performs better. If you need known performance or a product with documented handling guidance, this hobby recipe does not provide that evidence.
Quick Recap
Best Value
- ✔️EXCELLENT QUALITY :High purity, Advanced RMA -Rosin Midly Activated- Liquid flux formula, RoHS Certificate Compliant, Organic, Environmental friendly soldering liquid flux . Formulation for electronic soldering applications. It is effective in removing oxides from Tin-Lead, Lead-free, Gold, Silver and Copper alloys.
- ✔️ENOUGHT QUANTITY: The package includes 1 High Quality Dropper of soldering liquid flux, 30 ml net Volume. Excellent Immersion, wettability, chemical and technical properties. Thus, Enough quantity for your use. Strong soldering and welding power resulting strong low residual joints
- ✔️NON-CORROSIVE: Formulation with neutral pH, no corrosion involve after soldering process. Rosin is not conductive in dry conditions and has good insulation. Is not corrosive to metal surfaces such as circuit boards
- ✔️OXIDATION RESISTANCE: Anti-oxidation effect through soldering , desoldering, rework and reflow electronic processes for their high boiling formulation components. Giving as a result smooth, shiny and uniform soldering joints.
- ✔️NON TOXIC: Organic High Purity formulation, stable performance and low volatility for long use cycles, no irritant smell, Lead-free, Zinc Chloride-free and Ammonium Chloride-free.
Rank #4
- 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!
- 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
- Does not need to be cleaned
- Formulated for use with tin/lead and lead-free alloys
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