"for the reviewer above- this is a traditional flux you muppet! that means that you have to clean both pipe and fitting thoroughly before fluxing. provided you do that then a traditional flux will never let you down. this product is absolutely fine, just make sure you use it properly."
"Having used Powerflow for years, I thought I would give the Screwfix flux a go as it was cheaper, even with a perfectly clean joint the solder flow was poor and the joint looked dirty, so I resorted to scraping out my empty Powerflow containers, solder flowed and a clean perfect joint, the Screwfix flux has no self cleaning agent in it as far as I can tell.."