Things To Consider Before Buying A Microwave Kiln

What is a microwave kiln?

A microwave kiln is a device which you place into a conventional microwave in order for it to act like a kiln. Microwave kilns are more suited to a number of smaller projects, particularly glass work and some small fine clay work, as it is not able to reach the temperatures required for larger pottery projects.

Consider what you can fire in a microwave kiln

As mentioned above, not all firing projects are suitable to be processed in a microwave kiln. Most ceramics, for example, require a much higher heat than a microwave kiln can generate. Generally, microwave kilns can reach a maximum temperature of around 900°C, which is most suited to glass and jewelry projects. 

Consider the size

Your kiln will need to fit nicely in your microwave in order for it to function properly. Microwave kilns can range in size, from smaller ones that measure around 2 ¾ inches in size to larger ones that can measure around 6 ¼ inches in diameter. If you are a novice, it is better to begin with a smaller microwave kiln to better control the heat and stability of the kiln in the microwave.

You need to know the time taken to heat and to cool

It’s worth bearing in mind that it takes between 5 to 10 minutes for a microwave kiln to reach peak temperature ranges depending on the size, the work being fired, and the microwave’s power output. After the firing, the kiln needs to cool for at least 20 minutes before being opened and a longer time should be allowed for larger kilns.

Glass slippage can be a problem

Glass slippage is something to consider when using a microwave kiln for glass. Accidental knocking of the lid of the microwave kiln can cause the glass to slip inside the kiln. This can also be caused by an uneven plate inside the microwave causing an uneven wobble on rotation. Another form of slipping can be caused by heating too rapidly, which can cause the glass to crack or result in hot glass “gluing” itself onto the base or the sides of the microwave kiln. 

Understand what other materials you may need

Fiber paper may be used to help line the kiln and many models include this as standard, to prevent the glass sticking to the kiln. You should always wear gloves when handling fiber paper, and a respirator to avoid inhaling any dust following removal of your wares. You can also keep your kiln clean and free of dust by using kiln wash. Because of the heat involved, you’ll also need a heat resistant tile or mat to place your kiln on when removed from the microwave and also some kiln gloves to handle the kiln and wares.

Can I use a microwave kiln for metal?

Certain glass and jewelry projects can include metal as part of their design, so can a microwave kiln handle metal? The simple answer is yes you can, without causing the sparks that you would expect. You will need to conduct some experimentation however, as certain metals can turn black through oxidization.

Consider the safety aspects of using a microwave kiln

As mentioned above, the fiber paper disintegrates after firing, leaving a residual dust behind that can contain silica. You should therefore always wear a respirator. You also need to ensure that there is sufficient room between the vent hole in the top of the kiln and the ceiling of the microwave, as this releases a lot of heat. It may also be worth considering having a dedicated microwave to carry out this practice, that is not used for food items. The residue from various materials can be left in the microwave, so at the very least a thorough clean of the microwave should be made after each firing.

Microwave kiln running costs

Your primary consideration should be the amount of energy consumed and how regularly you use your microwave to heat your kiln. Modern microwaves are pretty energy efficient and so you should be able to maximise the energy that you use. You will also need to consider the size of your kiln and the project that you are looking to fire. Larger artefacts in larger kilns will inevitably require a longer heating time and therefore additional energy costs. You will also need to factor in the additional materials such as kiln wash and fiber paper when considering your costs. Microwave kilns have a finite lifespan, and like larger electric kilns, they lose potency over time. This will lead to longer times for heating which need to be factored in.

Although a microwave kiln is not a replacement for a larger stand alone kiln, it is the perfect solution for smaller projects and to test smaller wares or designs. They can even be used to make small scale models of larger projects that can be then scaled up in your larger kiln.

What to do next

If you have any further questions regarding microwave kilns and which kiln is suitable for your needs, please do not hesitate to contact us.

Although microwave kilns are suitable for small projects, they do not offer much scope for larger scale projects or more commercial ventures. If you are looking to create pottery or to undertake a business venture, then a microwave kiln is probably not suitable for your needs. There are many free standing kilns available to buy which you can heat to a much higher temperature than microwave kilns and can fire other materials such as clay. Please view our range of kilns here to see if there is one that suits your project.

Additional resources on kilns and pottery

• How to make food safe pottery
• How to make pottery at home
• What to consider when buying an Olympic kiln