DIY Flux – Make cheap flux at home.

Posted by on June 6, 2012

EE Gold.

If you’ve been soldering for a while now, you probably know what a wonderful thing flux can be, but if you haven’t and you just heard about it, you should still consider reading this article for I’m going to give you a few tips on how to make flux at home, cheap and easy.

Materials required:

  • Solvent, this can be isopropyl alcohol or rubbing alcohol in case you can’t source the former, the latter will leave several residues behind but it’s still useful. Other solvents can be used, including Acetone — But I don’t recommend it.
  • Colophony rosin, it has to be crystallized and you can find it in some hardware and music stores. The latter tend to sell molten blocks of it, which isn’t as good for this purpose but will work nonetheless. Another place to find it (mind you, lower quality rosin) is at the fitness store, rosin is used to give you an improved grip. It is therefore also sold at any outdoor store that carries climbing equipment.
  • Container with tight lid, a jelly jar would work fine
  • Syringe or small bottle with nozzle
  • Assorted tools from your bench

How to:

Place the rosin inside the jar, if you can’t wait for it to dissolve you’d want to grind up the crystals to a fine dust, this will vastly improve the time it takes to dissolve from hours to minutes. Add your solvent, start with a small amount and keep adding until you are happy with the way your flux behaves. You may want to wait at least an hour for all the rosin to dissolve properly anyway. That’s all there is to it, an interesting thing I noticed with my old batch of flux (probably two years old by now) is that it actually smells like whiskey, so keep it away from any alcoholics eh!


About 60ml of solvent per 6 grams of rosin was used in this case, giving a relatively heavy flux.

Ready to be used! (The remaining flux is kept in the tightly sealed container and this smaller bottle is used to sprinkle the flux onto wires, braids, pads, etc)

A word on ratios:

There is no ideal rosin to solvent ratio, it all depends on what you’re doing. For instance if you are tinning heavy wires, a thicker / heavier flux will serve you better than a very runny, thin flux that would otherwise serve you better if you were working with SMT, for example drag-soldering a fine pitch IC. For this reason I can only recommend you experiment until you find the perfect ratio for your work. But I will nonetheless give you a couple estimates based on my observations over the years.

  • Heavy flux:
    Ideal for tinning wires and heavy de-soldering jobs
    60ml of solvent – 6 grams of rosin
  • Medium flux
    Suited for most applications
    60ml of solvent – 4 grams of rosin
  • Light flux
    Used mostly in drag-soldering:
    60ml of solvent – 2 grams of rosin

More to come?


To clean it up you just need some extra solvent. Sorry, this is not a “no-clean” flux.

If you want to make flux paste the method is similar but involves heating the mixture and almost reversing the ratios as well. I’m not a big fan of this method since it can lead to an almost uncontrollable fire, but other than that the end-result may be worth it for you.


That’s it, enjoy and let me know if you’ve got any recipes of your own!




11 Comments on DIY Flux – Make cheap flux at home.


  1. Stephen says:

    this really works! thanks a bunch!!
    im not buying any more kester flux pens after this! they dry out and cost a fortune anyway!

    • GuShH says:

      Of course it works! — You just need to take a few minutes of your time to mix it up and it’ll last you for a long time.

      I’m still trying to decipher what these no-clean flux patents say… lots of strange chemicals, which I don’t have access too so clearly most people wouldn’t either. But, there has to be an easier way. Gotta keep looking.

  2. […] wrote a guide for making your own rosin-based solder flux. According to [Stephen] — who sent in the tip and tried this method himself — is works […]

  3. […] wrote a guide for making your own rosin-based solder flux. According to [Stephen] — who sent in the tip and tried this method himself — is works well, […]

  4. […] wrote a guide for making your own rosin-based solder flux. According to [Stephen] — who sent in the tip and tried this method himself — is works well, […]

  5. […] wrote a guide for making your own rosin-based solder flux. According to [Stephen] — who sent in the tip and tried this method himself — is works well, […]

  6. Moggen says:

    I made my own flux with these ingredients:
    + Some 99% Isopropyl alcohol bought at a local retailer (Kjell&Company in Sweden).

    Good stuff, not too much smoke. Works well with SMD soldering too.

    The remains of the resin protects the leads and pads, but can be easily cleaned with some isopropyl alcohol if it became too messy.

    I used a non-rosin resin flux pen before (Stannol X32-10I). A “no-clean” non-corrosive flux but it leaves a lot of white powdery remains that is hard to clean away, so I only use my own flux now.

    DE are cheap, but you may have to wait for 2-4 weeks to get the items.

  7. Tom Price says:

    I tried making flux from pine gum, literally scraped from a tree, dissolved in 99% isopropyl alcohol overnight and dripped through a coffee filter. It’s fairly think but seems to make a nice flux for SMT soldering. Apparently you can add a little glycerol to help prevent smoking but I have not found that to be a problem, even using lead free solder with my iron set at 400 oC.

    There’s a bit of amateur video here 🙂

    • GuShH says:

      That’s neat, although it makes me wonder whether you also mined for lead and tin to make your own solder! – Now that’s gonna earn you some MacGyver points!
      The rosin we all use also comes from pine trees, except they extract it using industrial methods so it ends up being cheaper for us freaks. It ought to mostly be a mixture of multiple types of pine trees, not just one though.

      Glycerine is used in a few commercial products to reduce “smoke”, so it may be worth a shot. I recall reading this in the patent file of a no-clean flux, of course they had about 10 other chemicals I couldn’t identify… Research still going on the diy flux gel. Tip: regular gel alcohol doesn’t seem to work properly…

  8. Sinisa says:

    Does this flux toxical and danger for health???