The Best Flux For Soldering Copper Pipe

The right flux ensures that joints on copper pipe aren’t just leak free; but stay that way for years to come.

Flux paste creates a chemical reaction so that when solder is melted it sticks to the copper. Naturally, some flux designed for soldering copper pipe is better than others.

Whether you are a bathroom fitter, plumber or gas engineer, you’re going to need flux. So, what’s the best flux for soldering copper pipe?

Some engineers have a personal favourite, some will use any brand. But, from my experience working in a large plumbing merchants for over 2 years, here are the best sellers:


Laco Flux Paste

Size: 475g

Laco Flux Paste is self-cleaning and designed for not just copper, but brass, lead and zinc too. It can be used on both water and gas installations.

  • Acid-free
  • Non-toxic
  • Lead-free
  • Zinc chloride free
  • WRAS approved.

Fernox/FRY Powerflow Soldering Flux

Size: 100-350g

Fernox/FRY Powerflow flux is a soft paste. Like Laco Flux, it’s self-cleaning and incredibly easy apply to most metals and alloys; suitable for both gas and water installations.

Fernox/FRY Powerflow is WRAS approved and can be used with both lead & lead-free solder.

Wiseman’s Everflux

Size: 250g

Wiseman’s Everflux is WRAS approved and comes in a smaller 250g pot. There’s some slight give in Everflux, so joints can be adjusted (slightly) after the solder has been applied.

It’s suitable for gas and water installations, as well as both leaded and unleaded solder.

Which is The Best Flux For Soldering?

Our pick for the best soldering flux? We tend to lean towards Fernox Fry Powerflow Flux, but we’d be happy (and have been happy) using any of the flux products mentioned in this review.

Don’t forget to grab a brush for application!