Although creating a setting and firing certain gemstones (do NOT attempt unless you are 100% certain a gemstone can withstand the temperature of firing!) is a common practice within the metal clay community, soldering has been used in metalwork jewelry making for centuries. The skill of soldering is essential to expanding capabilities and opening creative avenues.
Although fully sintered metal clay can be considered "metal", meaning that the techniques of soldering are the same as fabricated metals but there are some considerations to keep in mind.
Metals created from metal clay have specific properties when compared to most fabricated metals, "sheet metals" for example.
The first element you may encounter is warping. There are a couple of reasons why metal clay can warp during the firing process;
Accelerated drying. (We addressed this in another post)
Insufficient support during firing.
High (< 20%) shrinkage rate.
If you have experience soldering, it becomes immediately apparent why a warped base will pose a challenge to soldering. Soldering to an uneven surface is to be avoided unless the painful removal of hair is one of your "things". With advanced soldering skills, it is possible to fill small gaps, but in general 0.5 mm should be the maximum space you expect solder to fill.
Having spend more hours than I would like to admit correcting a warped creation in order to solder the gemstone setting, I am convinced that the prevention (or minimization) of warping is by far the better path to follow.
Can warping be corrected? Simple answer: Yes, but understand that you will be entering "Alice's Rabbit Hole", so make sure you pack plenty of patience.
The next important difference between metal from metal clay and fabricated metals is "POROSITY".
Even when you ensure optimal sintering during firing, the metal created during firing will be much more porous than fabricated metals. This is due to the fact that the metal particles in metal clay are "fused" during the firing process in the same way as most metals are fabricated. Although on a microscopic level, the metal may still contain small pockets of non-fused particles. However, fabricated metals undergo a second process of compression which rearranges the metal particles creating a more dense metal.
So the surface of metal clay metals will tend to be more porous than fabricated metals. This is a good thing as the surface will absorb just a little more solder, making the result just that little bit more stronger.
The flip side is, metal clay metals will also absorb more oils from the fingers when touching! This is one of the primary reasons solder fails. So ALWAYS clean your metal clay metals surface thoroughly with alcohol.
In conclusion, soldering to metal clay metals is no more challenging than soldering on fabricated metals, IF the correct steps have been taken to minimize warping.
If you are considering starting to solder, my Sky Guide 6 (Artisan Grade Soldering) tutorial is a great way to get you started.
If you are looking to update or upgrade your soldering skills, then my Sky Guide 7 (Jewelers Grade Soldering) tutorial will provide you with an in-depth insight into this essential jewelry making skill.
Have a question about soldering on metal clay? You can get direct answers from our Facebook Metal Clay Learning Hub group.