Why Does Solder Bubble and Splatter When Soldering
It is caused by flux boiling through the solder you’re laying down. That’s why you notice it more on the second side of a project – by then you have sealed off the other side, it can’t splatter out the back. As you may have guessed, the best thing you can do to limit this is use less flux.
The other possibility is that your soldering iron is hotter than necessary and causing more boiling. If you are sure you’re not using too much flux, try putting a temperature control on your iron.
Submitted by Wanda Shorty from an old issue of Stained Glass News
