Solder Defects
Solder Defects contains a variety of different issues that will show during the soldering process but could be caused by other processes.
Cold Joint
Cold Joints form when the material below the solder isn't heated sufficiently to allow a proper bond to form. Most often these are caused by "Painting" with the soldering iron as insufficient contact and/or dwell time was used. Cold joints are characterized by distinct layers forming with the solder. The only thing holding the solder in place is strictly friction from the metal conforming to the surface of the material below. In most cases these layers can be picked or peeled apart with relative ease.
Fixing these joints can be as simple as reheating the area the separation occurred at until the entire stack of material is molten again. If the solder shouldn't be where it is and formed a cold joint it can simply be picked/peeled off.
Solder Spike
Solder Spikes are from when insufficient or improper Flux is used or when the Flux has been consumed from working. These spikes are often very sharp protrusions formed when the iron is pulled away from the solder joint causing the surface tension of the solder to drag material out with it and finally break in the spike shape.
Adding an appropriate Flux or by adding more Flux onto the spike then reheating the area will quickly remove these.
Solder Pit/Solder Crater
Solder Pit or Solder Craters can be seen after a section of solder has been completed and has solidified. They can be identified by circulair pin holes that have formed in the solder joint. These occur when a material within the join has offgased or changed state. The most common reason these form is from trapped flux within the joint boiling off.
Avoiding this can be simply done by reducing the amount of flux applied to a given area. If they have already formed they can easily be fixed by passing the iron over the area again slowly allowing the trapped gas or material to leave the area. Once the boiling stops, the joint should finish smooth.
Solder Shrinkage Line
Solder Shrinkage Lines form when insufficient solder is on the joint in the molten state, then during the transition from the molten to solid state the solder contracts leaving a small dip/deformation in the solder.
While these aren't really necessarily always a defect many people attempt to avoid them when attempting to get super smooth lines. Fixing them can be done by dragging the iron across the full joint in one smooth motion while adding slightly more solder then dragging off onto the glass or directly picking up the iron. Sometimes simply melting the area of a line while adding more solder and removing the iron will solve the problem.
Adhesive Inclusions
Adhesive Inclusion come from the adhesive of Foil being melted or "Cooked" then being pressed out from under the foil. This is commonly seen where overlaps that don't perfectly align or where the overlapping ends of the Foil wrap are. They can also be found on corners or other areas where the Foil was allowed to fold over itself exposing the adhesive side up. As solder doesn't stick to the adhesive it will leave bare spots or indents with this black goo contained within it.
Repair of areas like this will require the adhesive goo to be removed before the joint will smooth out properly. This may require the iron to be placed on the joint and then used to slide back and forth over the area to scrape off the adhesive goo. In some cases it may require using the iron to purposely remove the adhesive below by heating it up and forcing it out.
Carbon Buildup/Black Specks
Carbon Buildup or Black Specks left in the solder are signs of an iron that isn't being cleaned frequently enough. These hard bits are small particles of carbon that have formed from organic materials burning in/on the solder or iron tip. They will often become embedded in the solder that can't be wiped off.
As these particles float on the molten solder, simply cleaning the iron and passing the iron back over the area will remove them.
Dross Buildup/Oxide Buildup/Gray Specks
Dross Buildup, Oxide Buildup or Gray Specks are small bits of metal oxides that have formed and will float on the top of the solder. The could be from a dirty roll of solder or just from regular use of the iron. As the oxides that make them up melt at higher temperatures than what we are working with they will slowly collect on the tip. They can often become embedded in the solder creating rough spots that don't wipe off.
Removing these particles requires you to clean your iron tip and then pass back over the line again so they float onto the iron.
Mushroom Solder
Mushroom Solder is when too much solder is applied to the joint and it flows off the joint and onto the glass. As solder won't bond to the glass it will create a mushroom looking shape where the edges curl around to itself.
Removing solder and passing back over the line to even it out will solve this issue.
V Splits
V Splits are where the underlying foil has ripped or split causing a small gap to form in the solder due to the surface tension keeping it from bridging over the gap.
These should ideally be repaired before any solder is applied by using Foil Saddles as required or just replacing the section of foil entirely. If solder is already applied as much as possible needs to be removed and a small section of foil placed over the top.