FAQs

We are constantly developing new glazes. If there’s something specific that you’re looking for, let us know and we may be able to add it to our range.

Yes, glazes can be layered, but keep in mind that this may result in changes to the way the glazes behave on their own, such as crawling or running. Make sure glazes aren’t applied too thickly. If trying a combination for the first time we recommend taking precautions, such as trying it on a test tile, leaving extra space unglazed at the bottom of the pot, and using a cookie to avoid damaging kiln shelves. 

Always apply glaze to ceramic pieces that have been bisque fired (that's when the dried, raw clay gets put into its first firing that goes to 1000 degrees). These glazes fire to stoneware temperatures, therefore can only be applied on stoneware clay (clay that fires between 1280-1300 degrees celsius).

We always suggest testing your glazes first on a small or unwanted piece (before committing to your favourites), so you know exactly what effect you're after. Adding more or less layers of a glaze to a bisque piece can have different effects - so it's always good to play around with them to see what you like most!

All of our glazes layer well together, however we suggest layering no more than two different glazes at the same time as chemical reactions can occur when your pieces are fired which could potentially cause damage to your pieces and the kiln. It's always good to test different layered glazes as there are many different effects and possibilities depending on which glazes you choose.

All of our glaze range is food safe, however not all food safe glazes are suitable for dinnerware. 

The international standard for glazes to be considered food safe is that any leaching of lead and cadmium are minimal and within safe limits. For this reason we don’t use lead or cadmium to make our glazes. The exception is our candypop and orange sherbert glazes, which include stains containing cadmium, however stains are considered safe due to the manufacturing methods used to encapsulate the minerals in the stain. 

Other metals that we use in our glazes are considered safe in low doses, but toxic in high doses. For this reason we develop our glazes to have stable chemistry, to minimise leaching.

If you are concerned about glaze toxicity, or want to use a glaze that isn’t suited to dinnerware, we recommend using a liner glaze.

A fully vitrified glossy glaze is the most likely to provide a fully sealed, durable surface, with no open pores that food can get into. 

Matte glazes can be used for dinnerware, however they may be harder to clean, and are more likely to become stained over time when used with certain foods and drinks (for example, tea, coffee, tomato, turmeric, etc). This doesn’t necessarily mean that the item is unsafe to use, and there are reputable studio potters who use matte glazes on tableware, but it may be undesirable for aesthetic reasons. Matte glazes can also be more prone to scratches or marking from cutlery and general wear and tear. 

Many consider crazed glazes to be unsafe, as they are likely to stain, and can potentially harbour bacteria or mould in the cracks. Testing has shown however that proper cleaning is enough to remove bacteria from crazed glaze surfaces. The bigger issue to consider with crazing is that it weakens the object, making it easier to break.

Unstable or improperly fired glazes may leach materials from the glaze into food or drinks. While most of the materials in glazes are considered non toxic, some colourants, such as copper, cobalt or chrome, are toxic in high doses. It’s important to remember that the dose makes the poison, and if a glaze does leach, it may still be within safe limits. Generally a glaze would need to have very unstable chemistry, be underfired, or contain very high amounts of metallic oxides to leach a dangerous amount. An example of this would be metallic glazes, which almost always contain very high amounts of metallic oxides, and should only be used on decorative objects. 

Most special effects glazes, including crystalline, metallic, crater and crawl glazes are not suitable for food surfaces.  

Crazing occurs when there is a mismatch in the thermal expansion of a clay body and the glaze. As the glaze cools it shrinks more the clay, causing tension, and resulting in fine cracks appearing in the glaze. Crazing doesn’t always appear straight out of the kiln. It may appear over time as an object is used. Because different clays have different shrinkage rates, a glaze may fit perfectly on one clay body, and craze on another. If you intend to sell your pottery, it is important to do your own tests to determine if a particular glaze is a good fit for the clay body you want to use it with. 

There are a few things that can cause crawling. Most commonly it is because the glaze has been applied too thickly, or the bisqued surface was contaminated with dust or oils (eg. from moisturiser). Before glazing, wipe bisqueware with a damp (not wet!) sponge to remove dust. Always handle bisqueware with clean dry hands, or use gloves to avoid contamination. 

This is called hardpanning, and is a result of deflocculation. Glaze is mainly made up of finely crushed rocks that are held in suspension by clay particles, which have a positive and negative side (like magnets). Sometimes sodium ions present in the glaze bond to the clay particles, changing the charge of the clay particles, causing them to repel each other. Think of it like when you try to push two positive sides of a magnet together. The clay is no longer able to keep the glaze in suspension, and the materials settle on the bottom in a hard layer. To fix this we add magnesium sulfate (epsom salts), which neutralises the charge of the clay particles, enabling the materials to come back into suspension. 

This is a frustrating part of glaze maintenance that cannot be prevented, but the fix is relatively simple once you learn it. 

First, you will need to make an epsom salt solution. You can buy epsom salts at most supermarkets, in the health and beauty aisle. They will usually be near first aid or bath products. Pour some hot (it doesn’t need to be boiling) water into a container. Stir in some epsom salts, continuing to add them until they are no longer dissolving into the solution, and are starting to collect on the bottom. This is an epsom salt saturated solution, that you can now keep on hand to use any time a glaze needs to be flocculated. 

To flocculate your glaze add a SMALL amount of epsom salt solution to the glaze. Start with 1-2 drops. You can now mix your glaze again. If it is badly settled, and still not mixing in, use a loop tool (like what you would use for trimming your pots) to carve into the hard layer and get it moving again. This can take some time and if you’re finding it hard to get all of the lumps out you can wear gloves and break up any clumps with your fingers, or use a glaze sieve. Once it is fully mixed, you may find that it still seems to be settling quickly. If this happens you can add more epsom salt solution, but add just one drop at a time while mixing. Too much solution will thicken your glaze and make it hard to apply. A 500ml brush on container should only need a few drops of solution at most.   

If you want to understand more about this topic, or see it explained in video format, these are some useful resources:

https://suemcleodceramics.com/how-to-fix-a-hard-panned-glaze-with-epsom-salts/

https://suemcleodceramics.com/how-to-make-a-saturated-epsom-salt-solution-to-flocculate-your-glazes/

https://www.youtube.com/watch?v=fpQns05RdVU&t=19s

Note: these resources are discussing dipping glazes, which are more likely to deflocculate, so not all of the information in them will be relevant to brush on glazes. 

This is usually caused by microbial growth, or the breakdown of organic materials in the glaze. This shouldn’t affect the fired result, but you can mix in a couple of drops of dettol or household bleach to kill any bacteria that may be present. 

These are called oolites! They are small calcium crystals that can form in a glaze over time, especially if the glaze has been exposed to cold temperatures. They will impact your fired glaze surface, so it’s best to sieve them out and discard them. 

Yes! If your brush on glaze consistency is thicker than you would like, you can add water. Be careful to add only a little at a time, as once it’s added, you won’t be able to take it back out, and too much water may impact brushability. Alternatively you can add a brushing medium. 

Sometimes, though it’s not recommended. Unlike underglazes, which can be mixed like paints, glaze gets its colour and texture from the chemical reaction between the ingredients. Mixing a yellow glaze with a red glaze may not give you orange, and the surface quality could be entirely different from the original glazes. Additionally, mixing glazes could create a glaze with unstable chemistry that is prone to leaching, or lacks durability, making it unsuitable for use on dinnerware. 

This is most often an application issue. Every glaze behaves differently. Some like a thin application, some need to be a little thicker to get the best colour result. 

To get the best results, we recommend testing each brush on glaze on test tile, showing 1, 2, 3, 4 and 5 coats of glaze. This will help you to get to know that particular glaze, and how many coats will give you the result you are looking for. In some cases a glaze may completely change colour depending on how many layers are applied. A good example of this is Seafoam, which is green when applied thinly, and light blue when it’s thicker. Some glazes will change colour or texture if you are using darker or speckled clay bodies, so if you are using different clays, be sure to test the glaze on each one.

You may also find that some glazes pinhole or crawl craze when they are applied too thickly, or used on different clay bodies, so testing is also useful to help you avoid glaze defects on your work.

Remember to use vertical test tiles if you plan to use the glazes on vertical surfaces, so you can see the movement of the glaze. 

If you are still having trouble with your glaze results after testing, please reach out and we will be happy to help diagnose the issue.