Laco Flux

Laco Flux is a paste soldering flux designed to prepare metal surfaces before soldering, removing the oxide layer that would otherwise prevent solder from flowing and bonding correctly. Whether you are sweating copper pipe joints, soldering electrical connections, or working with sheet metal, getting a clean joint starts with the right flux. This is it.

The paste consistency makes it straightforward to apply exactly where you need it, without the mess you get from liquid flux running where it shouldn’t. A small amount goes a long way, which is why the 475g tub is popular with tradespeople who go through it regularly on bigger jobs. The 125g size is handy for the van or smaller plumbing tasks where you don’t want a full tub rattling around.

Where Laco Flux Gets Used on Site

Plumbers reach for this most often when making copper-to-copper or copper-to-fitting solder joints on water and heating systems. It works across a wide range of metals including copper, brass and tinplate, making it equally useful for sheet metal fabrication and light electrical soldering work. On a busy plumbing job, the difference between a joint that takes first time and one you have to redo twice often comes down to flux application — too little and the solder balls up, too much and you are burning it off before the solder even flows.

Applying Laco Flux Correctly

Apply a thin, even coat to the cleaned surface before heating. You do not need to pack it on — it’s flux, not filler. The heat from your torch or iron activates it, drawing the solder into the joint. Clean off any residue once the joint has cooled, particularly on plumbing work, to avoid long-term corrosion around the fitting.

Available in 125g and 475g sizes, with honest bulk pricing from Discount Trade Supplies.