What does “get out quickly” have to do with soldering?

Recently I have noticed a number of students having trouble with their solder joins. They are seeing their solder flow, but when testing the strength of the solder join – like flaring a ring – the join fails.

Since most of my students use butane torches, I was a little baffled by this. Generally, the issue with the small torches is getting enough heat to make sure that the solder flows.

But this wasn’t the case, as they were seeing the solder flow.

One of the things I talk about when teaching soldering is the goal is really to get in and get out as quickly as possible. Heating the metal to the temp, have the solder flow through the seam and get out.

We also talk about how solder follows heat.

I think what is confusing here, is I often teach with the butane torches which takes a while to get the metal to the correct temperature for the solder. However once the metal is at the correct temperature keeping it there does not take as much energy.

So… what is the problem? In the case of rings, the ring is being heated to the correct temperature, the solder if flowing, and in the attempt to bring the solder through the seam, the heat is left too long on the seam.

The extra heat is causing the solder to flow through the seam and out the other side. Depending on how much solder gets pulled out of the join, this can cause a weak join.

The solution? Once you see your solder flow through the join…. Stop. If you are pulling the solder through a join, like on a ring, as soon as you see it come through…. Stop.

In other words, “get out quickly”.

Happy soldering…