Yes you can use that.
I have a old can of soldering paste for clean jobs,
but if things are dirty, cut muratic acid is the only thing that will clean them up to allow a good sweat joint.
You must cut it with zinc, a jar lid works well,do not dilute it with water.
Small snippings of the zinc are added till the acid quits eating them, then it is diluted properly to do a great job of cleaning material for soldering
This past winter I repaired a 1915 honey comb radiator, @ that age, it needed a good cleaning acid.
A soldering paste was just not up to the job.
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