Powerflow Flux by Fernox is a reliable soldering flux paste for copper pipework and fittings. Available in 100g and 350g tubs, it cleans and prepares joints before soldering to ensure a clean, leak-free connection every time.
Size
QTY
Price
QTY
100g small
1
£7.49£8.99
350g large
10
£12.99£15.59
Powerflow Flux is the go-to soldering paste for plumbers working with copper pipe and fittings. Made by Fernox, one of the most trusted names in the heating and plumbing trade, it does the job it needs to do: clean the metal surfaces, prevent oxidation during heating, and allow the solder to flow evenly into the joint. The result is a sound, leak-free connection. Simple as that.
The flux paste is applied to the cleaned pipe and fitting before heat is applied. As the joint reaches temperature, the flux activates, drawing the molten solder in and ensuring full coverage around the joint. Without flux, you are fighting oxidation the whole time, and solder that does not flow properly means joints that fail. There is no upside to skipping it.
Where Powerflow Flux Gets Used
This is a product used across domestic and commercial plumbing on a daily basis. Hot and cold water systems, central heating pipework, gas installations where permitted, and any copper-to-copper or copper-to-fitting joint that needs a reliable solder. It works with both lead-free and traditional solder, and it is suitable for end feed and solder ring fittings alike.
The 100g tub is a practical size to keep in a tool bag for day-to-day call-out work. The 350g tub makes more sense if you are fitting out a new build or doing a full system install where you will be soldering a lot of joints. Buying in bulk also makes sense here, with ten tubs available per box, so you are not running out mid-job.
Powerflow Flux has been a staple in the trade for years. It is not glamorous, but neither is a callback for a weeping joint.
Pro Tip: Apply flux sparingly and wipe away any excess after soldering, as residual flux left on the pipe can cause long-term corrosion if moisture gets to it.
Powerflow Flux is used wherever copper pipe is being joined by soldering. That covers domestic central heating systems, hot and cold water supplies, commercial plumbing installations, and light industrial pipework. It is suitable for use with end feed fittings and solder ring fittings, and works with lead-free solder as used in potable water systems. Heating engineers, gas engineers working with copper, and general plumbers all reach for this routinely.
Best For
Soldering copper pipe and fittings
Central heating pipework
Hot and cold water systems
End feed and solder ring fittings
New build and refurbishment plumbing
Compatible With
Copper pipe and fittings
Lead-free solder
Traditional tin/lead solder
End feed fittings
Solder ring fittings
Key Features
Prevents oxidation during soldering
Promotes even solder flow
Available in 100g and 350g tubs
Trusted Fernox formulation
Suitable for potable water systems
Not suitable for: Not suitable for use on stainless steel, aluminium, or non-metallic pipework. Not intended for use with push-fit or compression fittings where no soldering is involved.
Clean the pipe and fitting socket with emery cloth or wire wool before applying flux. Surfaces must be bright and free from grease or oxide. Apply a thin, even coat of Powerflow Flux to both the pipe end and the inside of the fitting socket, then assemble the joint and apply heat evenly with a blowtorch until the solder flows cleanly around the joint. Remove the heat source once solder is visible at the edge of the fitting.
Cut the copper pipe to length and remove any burrs with a pipe reamer or file
Clean the pipe end and the inside of the fitting socket using emery cloth or wire wool until the metal is bright
Apply a thin, even layer of Powerflow Flux to the outside of the pipe end
Apply flux to the inside of the fitting socket
Push the fitting firmly onto the pipe and ensure it is fully seated
Apply heat evenly around the joint using a blowtorch until the fitting is up to temperature
Touch the solder to the joint edge and allow it to draw in; remove heat once solder appears cleanly around the rim
Leave the joint to cool undisturbed, then wipe away any flux residue with a damp cloth
Is Powerflow Flux suitable for use on drinking water pipework?
Yes, when used with an approved lead-free solder, Powerflow Flux is suitable for potable water systems. Always ensure the solder you are using also meets the relevant standards for drinking water use.
What is the difference between the 100g and 350g tubs?
The 100g tub is ideal for everyday use and fits easily in a tool bag for call-out work. The 350g tub is better suited to larger installations or new build work where you are soldering a high volume of joints and do not want to run out halfway through.
Does Powerflow Flux need to be removed after soldering?
It is good practice to wipe away any excess flux residue with a damp cloth once the joint has cooled. Flux left on the pipe surface can cause corrosion over time, particularly in damp environments.
Powerflow Flux is a paste flux formulated by Fernox for use in copper soldering applications. It acts as a chemical cleaner and oxidation inhibitor during the soldering process, allowing solder to wet and flow across the joint surfaces evenly. Suitable for use with lead-free solders compliant with BS EN 29453, it meets the requirements for use in plumbing systems including potable water supplies.
Brand
Fernox
Product Type
Soldering Flux Paste
Available Sizes
100g, 350g
Suitable For
Copper pipe and fittings
Solder Compatibility
Lead-free and traditional tin/lead solder
Application Method
Apply with brush or spatula before soldering
Potable Water Suitable
Yes, when used with approved lead-free solder
Weight
N/A
Size
100g small, 350g large
Box Quantity
1, 10
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