Firing Glass With Metal Clay

Q: Can I fire glass along with metal clay

Yes, you can fire some silver metal clay along with glass in a kiln. Base metal clay on the other hand tend to have a firing temperature that is above the melting point of most glass. When working with metal clay and glass, the lower firing temperature clay types tend to be recommended, as a higher firing temperature could alter the glass or the coloring.

Due to the many variables with the many types & colors of glass and various metal clay brands, sales outlets usually recommend PMC3™ or Art Clay® Silver 650. Even with these clays, depending on the glass you are working with, you should keep in mind that you may need to adjust the firing temperature and/or schedule.

This does not mean that only these clay types can be used, but is merely a way of minimizing the variables that need to be considered. There are no short-cuts here....unless you have a good firing record that allows you to adjust your metal clay firing schedules by clay type, you will be entering the labyrinth with no compass!

The real challenge for most is discerning what "can be done" compared to "what should be done".

So the simple answer was "Yes" it can be done, but should you?

Considering that most get their information either through strategic online marketing presenting their products as easy to use or through social media via contributors presenting their successful projects, the unsuccessful results along with their challenges are not so readily published.

Before proceeding with this type of project, knowing the potential challenges will at least allow you evaluate the amount of time (& creative energy) to invest in your project.

With any metal clay, failure to fully sinter the metal is critical to the quality and commercial value of your project. This means that firing at temperatures very close to the metals melting point is usually the only way (besides VERY expensive specialty equipment) to ensure your project is fully sintered without bending it more than 90° to see if it cracks or breaks...Yikes

Quite often, we receive questions from artists that are confronted with a piece they sold breaking or arriving broken in shipping. After the initial impulse to blame the customer or the shipping carrier, the realization that silver (100% metal) should not crack or break due to it's property of flexibility hits home....then what caused the issue?

The following should point directly at the issue - Melting Point: Silver (fine) 1762 F / 961 C

Low Temp Silver Clay firing schedules:

The firing guide included in a package of PMC 3 lists the following firing options:

• 1650°F / 899°C for 2 hours

• 1560°F / 849°C for 20 minutes

• 1290°F / 699°C for 10 minutes

• 1200°F / 649°C for 20 minutes

• 1110°F / 599°C for 45 minutes

The insert from a package of Art Clay Silver lists:

• 1650°F / 899°C for 2 hours

• 1600°F / 871°C for 10 minutes

• 1560°F / 849°C for 10 minutes

• 1472°F / 811°C for 30 minutes

In both cases, you will note that the highest temperature schedule is only 62° C (143.6 F) below the melting point. Between 1110°F / 599°C and 1650°F / 899°C fine silver fuses while maintaining its form, but as we reduce the temp, the risk of the metal not fully fusing increases. So, is your metal clay sintered?

That may be fine for a fun gift project if it holds no real sentimental value....but to sell, there is a good reason why I choose traditional metalwork to set my gemstones, bone, glass or other.

So, should I co-fire glass and metal clay?

If you have a great deal of in-depth understanding of the chemical properties of metals and of metal clay, a very good experience with managing firing AND an in-depth understanding of the creative process, chemical properties and treatment of the multitude of glass-works then why not.........but keep in mind the high risk of your silver not sintering!

As co-firing glass or gemstones does not increase the value of your creations, ask yourself "why do I want to co-fire?" if your answer is "to save time", if this is based on your goal of selling. Then be open with yourself and your potential clients towards the undetermined quality.

If your answer is "because I don't have (or not comfortable with) traditional metal-work options", then why not consider an on-line video class focusing on soldering and bezel setting? This way, you will enhance your skills AND ensure the best quality for your creations.