In article nc, JR North wrote:
Heat the pipe only,

Wrong. Heat the *fitting* only. Heating only the pipe expands the pipe more
than it expands the fitting, reducing the space available for solder to wick
into the joint, and also makes the joint more likely to crack as it cools.

and prep the joint for best possible wicking. As
soon as the solder flows, remove the heat

Wrong again. Continue heating until the solder has been sucked into the entire
joint.

and pour cold water on the valve.

Wrong yet again. Doing so can crack the solder joint. Allow it to cool on its
own.