Flux Form - Liquid, Pen, Gel, or Solid: Which do you prefer?

Thread Starter


Joined Jul 18, 2023
Hello everyone,

I'm exploring the different forms of flux available - liquid, pen, gel, and solid.

What form of flux do you commonly use and why do you prefer it? Are there any specific reasons to chose one from over another ?

Thank you.


Joined Jun 5, 2013
All of those have their uses, it depends on how you build your projects.

I build my projects on PCBs using with mostly SMD components. I use a flux pen only. I have also used a solder paste syringe, but find it very awkward and I now solder everything by wetting the pads with the flux pen, then using very fine rosin core solder. When did through hole, I never used flux other than what is in the solder core.


Joined Jan 23, 2018
For some applications I use flux core solder, but for soldering bare copper wire I generally apply some paste flux in addition. That includes the non-tinned shield braid of coaxial cables. But paste flux does need to be removed after the soldering is complete.


Joined Mar 30, 2015
I use a liquid rosin based flux. I put an ounce or so in a glue bottle and take the cap off and use the tip to apply a drop of flux.

If it gets too thick, I thin it with 99% isopropyl alcohol.


Joined Mar 19, 2019
Yes, I have a loooong memory. Brylcreem, Dipity Doo, Aqua Velva, and Old Spice. Still using a bottle of Old Spice from the 60's. A little bit goes a long ways!