I had a plumber doing some work for me that did not sand the inside of fitting or the outside of pipe ends (on new pipe) that were to be soldered. He said it was a waste of time as flux takes care of it. He did ream everything and did sand existing pipes in ground that were badly corroded. I had always seen everyone sand. Is it a waste of time. I do some of my own soldering and wonder if this extra step has been a waste of time. What is everyone here’s opinion? I don’t want to pull it apart now. It is already done.
No cleaning is not a waste of time. Although some flux is self cleaning, it does not do as good of a job as sanding. You have less chance of a leak if you clean your pipe, and fitting prior to soldering. Especially someone who does not do it all the time I would reccomend that you do clean before adding flux and finishing the joint. Good luck.