Brittle solder joints

Hi Orchid,

We (the two of us) are both simultaneously experiencing brittle
solder joints, especially with our medium solder, as well as a
generally difficult time getting it to flow. We have tried to
eliminate all sources of contamination on the solder (clean
w/sandpaper then alcohol)and work itself, not overpickling it, etc.

The joins seem good when the solder flows but upon testing they are
brittle. The only difference is we have a new propane cylinder for
our cheapo bernzomatic torch and it tends to run hot when the bottle
is full and is difficult to control, perhaps we are overheating the
solder in an attempt to get it to flow? Often I find the piece is at
soldering temp (I know, Ive done this thousands of times with no
problem) but lately the solder just sits there until I touch it with
a hot pick. Our solder is old but we clean it well before we cut it,
and it’s the two of us both having this problem at the same time.
Any ideas on brittle joints and low-flow solder?

Thanks, Doug and Sarah.