Frequently Asked Questions

Click here to download a simple one-page general explanation on mixing glazes in dry form.

Detailed instructions from Laguna on mixing their dry glazes can be downloaded here

This series of videos by AMACO/BRENT covers mixing glazes, dipping, layering and making test tiles

This post ,  Using Additives such as CMC Gum to Beef up your Glazes, includes detailed information on how to use glaze additives to expand the possibilities in brushing, dipping and pouring as well as re-glazing your work.

Mixing your own glazes is money-saving as well as introducing another creative element to your pottery. There are plenty of resources online that provide procedures and recipes for mixing glazes from scratch using raw earth materials that are available at West Michigan Clay. In addition, we recommend the books listed below, which provide  background on processes and a great collection of glazes at various firing ranges to get you started.

Safety is an important concern when mixing glazes from dry glaze chemicals. Wear a good face mask to avoid inhaling dust. Some materials ,like wood or bone ash, are caustic and can burn the skin, so you need to wear latex or nitrile gloves to protect your skin when handling these materials. 

Glaze materials are measured by weight, not volume. Accuratly weighing glaze materials is critical to the outcome of your glazes. Most potters use either a good digital scale or balance. 

Adding water to your glaze mix is covered underour FAQ post on mixing dry glazes. Sieve your liquid glazes with an 80 or 100 mesh sieve once they are mixed with water.  Use CMC or similar material if brushing your glaze. Adding 1-3% bentonite in your dry mix will help keep the glaze materials in suspension and avoid hardpanning. 

The following books - some available at your local library or from Michigan Electronic Library (http://www.mel.org. ) - include a good background on mixing your own glazes and a variety of recipes for mid-range and high-fire glazes.

Mid-fire glazes:

• Mastering Cone 6 Glazes: Improving durability, fit and aesthetics by John Hesselberth and Ron Roy
• The Complete Guide to Mid-Range Glazes: Glazing and firing at cones 4-7 by John Britt

High-Fire glazes:

• The Complete Guide to High-Fire Glazes: Glazing and firing at Cone 10 by John Britt

More general references on glazing and decoration:

• The Ceramic Spectrum: A simplified approach to glaze and color development by Robin Hopper
• Making Marks: Discovering the ceramic surface by Robin Hopper

Another online resource with information on a variety of topics - including glazing - for beginning and experienced potters can be found at Ceramic Arts Network (https://ceramicartsnetwork.org/

Common glaze defects:      

•  Crawling  
• Shivering
• Crazing 
• Pitting/pinholing
• Blistering

This excerpt from the late Robin Hopper's book "The Ceramic Spectrum"  covers five common glaze defects with photo illustrations and suggested solutions. 

While you might think that glaze defects are less of an issue with commercial glazes, this is not necessarily the case, especially if you are new to  making and firing pottery.

•  Pay attention to the thickness of your glaze application.  This explanation on the DigitalFire website illustrates problems with glaze thickness.
• If you are layering glazes, it is better to apply the second layer before the first is bone dry.
•  The condition of your bisque prior to applying glaze is important. Dust/grease/errant wax can impair glaze adhesion to the bisqued surface and lead to a poor outcome.
• The bisque firing temperature and process can  impair the glaze outcome.  Some clays need more time to release gasses from the clay body during the bisque firing.  These gasses are then released during the glaze firing, causing surface defects as the glaze melts.
• Aspects of the glaze firing can contribute to glaze defects. Overfiring,  underfiring, holding and cooling speed can all affect glaze outcome.

This excerpt from the late Robin Hopper's book 'Making Marks: Decorating the Ceramic Surface" explains the difference between these materials and their application. Commercial underglazes are mostly engobes. You can create your own slips/engobes/underglazes using clay and additional ceramic materials to broaden your creative clay pallette.

It is best to store your moist ceramic materials in a location that avoids temperature extremes. Should you find that your clay and/or glazes have frozen, allow them to thaw before proceeding.

For  a detailed explanation on what happens when clay freezes, click here.

• Frozen glazes will just need to be mixed and possibly sieved through an 80-100 mesh sieve once it has returned to liquid form
• Frozen moist clay will require a strenuous wedging session to return it to its proper consistency. 
• WHAT ABOUT MY FROZEN WAX RESIST? - Wax resist will be damaged once frozen. You may try adding some denatured alcohol to the mix, letting it sit a while and stirring vigorously, but it is not likely to come back to a usable consistency.

YES. Unfired clay is reusable/recyclable and re-wettable. It isn't necessarily quick , but if you  are patient, it can be pretty easy.

• OLD SCHOOL METHOD - Break up the block of clay into smaller pieces (sledge hammer...?) and soak in a 5 gallon bucket. You will need to dry the slurry and wedge well before use. This Instructables link will give you the details.
• FOR A LESS LABOR-INTENSIVE BUT LENGTHIER PROCESS, this video shows you how to reconstitute an entire block of dry clay without the sledge hammer. You can try this method with clay that is too hard to work, but not bone dry. In that instance, you may want to poke some holes into the not-quite-dry clay to speed up the soaking process and use less water. 
  • The same presenter uses the same method to rehydrate a small piece of clay in 15 minutes in this video.

Yes and no. Yes, you can invest in more trimming tools. But if you have the tools you like, you can SHARPEN THEM.

You may use any number of sharpening tools (files, emery cloth, stones, rotary tools, bench grinders - be gentle with these!). You will probably have more success using more than one sharpening tool, since trimming tools have a wide variety of blade configurations.

Over time and use, your tools will still need to be replaced, but you can prolong their usefulness with proper maintenance.

• For a detailed description of the different pottery trimming tool types and materials, as well as an in-depth understanding of sharpening approaches, you may want to watch this video. 
• This article from Pottery Making Illustrated covers tool types and approaches to sharpening as well, but in a text format

The two main opacifiers used in making ceramic glazes are zirconium silicate (sold as Zircopax, Ultrox, etc) and tin oxide. Due to the cost difference, glaze recipes often use zirconium silicate to opacify a glaze. 

Tin oxide is not as  effective as an opacifier for white glazes in high fire reduction. However, the presence or absence of tin oxide impacts the colors produced by metallic oxides in both oxidation and reduction. Because of this, as well as the different kind of 'whiteness' when used to produce white glazes, substituting one opacifier for another is not straightforward. 

See this post on Ceramic Arts Network for a demonstration of differences in applying each of these two opacifiers.

If you like to brush your glazes on your ware, or even if you pour/dip and then brush, these two videos may provide some insights that will give you a boost:

This link (https://www.amaco.com/clay_how_tos/180) from Amaco gives information on brushes, brushing, and some on layering your glazes (Potters Choice specifically)

In this link (https://www.youtube.com/watch?v=2OOWC_rgJNo) the presenter gives many tips on brushing, brushes and documenting your work and outcome.

Yes. Some potters use/prefer this method to produce effects that cannot be obtained by dipping, pouring or brushing.

• WHAT DO I NEED? - Spraying glazes requires a paint spray gun (preferably a gravity feed HVLP spray gun, available at hardware/big box stores) and an air compressor. You can get by with a compressor that is smaller than the ones painters use. 
  • You will also need a good face mask (n95, for instance) and goggles. Some folks use gloves as they spray. 
• HOW DO I DO IT? There are numerous YouTube videos available that demonstrate spraying glazes on pottery (just Google 'spray glazes on pottery' and watch a few). 
  • This document (https://digitalfire.com/4sight/datasheets/GlazeSprayingForCraftPotter.pdf) is an excellent resource for anyone wanting to try spraying glazes on their work. The article provides enough background to get started as well as ways to avoid some common mistakes a beginner may encounter.
• WHERE CAN I SPRAY GLAZES? In a perfect world you will have access to a well-ventilated and exhaust-supplied spray booth. If you are handy with carpentry tools, there are plenty of DIY spray booth plans online. Google 'DIY spray booth' and take your pick. If you are still in the experimental stage or don't know that you will be doing a lot of spraying, you can take your work outside on a still, dry day and spray away. Don't forget your protective equipment!

If you recently invested in a new or used electric kiln, you may have some questions about long-term maintenance and repair. These are the parts of your kiln that will likely require some attention from time to time:

• Elements (these are what heat your kiln)
• Thermocouples (these sense the temperature in the kiln)
• Relays/Switches (these control how often power is sent to your elements with an electronically controlled kiln. Older kilns have manual switches)
• Fuses (these protect your electronic controller from getting fried!)
• Bricks - It is possible to replace/repair bricks in your kiln, but best to be careful not to damage them in the first place...)

TROUBLESHOOTING KILN PROBLEMS:

• Skutt has troubleshooting resources for their kilns at https://skutt.com/skutt-resources/troubleshooting/ 
• Common problems include:
  • Getting an error code prior to or during the firing.
  • Uneven heating (some parts of kiln do not reach temperature, others may overfire.). Use witness cones throughout your kiln to monitor performance.
  • Kiln doesn't reach temperature at all.
  • No power to the kiln or controller.

BE CAREFUL IF YOU CHOOSE TO TAKE ON YOUR OWN KILN REPAIR - KILNS PACK A POWERFUL PUNCH OF POTENTIALLY DEADLY CURRENT. Ensure that the power source to the kiln is disabled before doing any work on your kiln. IF IN DOUBT, HIRE A QUALIFIED ELECTRICIAN FOR YOUR REPAIRS.

Here are some resources that you may find helpful:

• Skutt provides a list of items that require maintenance and occasional repair at https://skutt.com/skutt-resources/repairs/ Information is available in video and text formats.
  • You can access a library of pdfs and answers to many of your questions for Skutt kiln repair at https://kilnparts.com/pages/learn-pdf-library-tutorials-and-general-kiln-repair-information
• Don't have a Skutt kiln? Most kilns are configured similarly, so the information you find in the above links may be useful in troubleshooting and repairing other kilns.