Is It Safe To Eat And Drink From Low Fire Clay?
Low fire clay is food safe when coated with a food-safe glaze. When coated with a food-safe glaze and fired to full maturity, unglazed clay surfaces may be regarded as food safe since the clay particles vitrify sufficiently. Clay and glaze are sufficiently melted together to form a waterproof surface. The result is a glaze coating where foods cannot penetrate the surface.
Glazed ceramic pottery can leach metals, harbor bacteria, and even flake off into food and drink, making it dangerous to eat and drink. Some ceramics, both imported and domestic, have been deemed unfit for human consumption, according to the FDA. Know more by reading my other article called: Is Glazed Ceramic Pottery Food Safe?
All surfaces that are directly connected with food or drink must have uniform, unbroken glassy surfaces, free from cracks, rough texturing places that water, juices, or oils might enter, to ensure a Ceramic Piece is “food safe.” These defects can be bacterial growth havens.
What Is Low Fire Clay?
Low-fire clay bodies are characterized by the temperature at which they mature, which is usually between 1700 and 2000 degrees Fahrenheit (927 and 1093 degrees Celsius). Low-fire clays are easy to deal with and don’t tend to shrink or warp.
Clay requires a mix of heat and time in the kiln to mature. The term “heatwork” refers to the combination of heat and time. It refers to how much energy was spent in the firing of a piece of pottery. It not just the temperature.
The quantity of “heatwork” used in most electric kilns is currently determined by digital temperature controllers. However, the cone system is still used to signal when clays and glazes are ready to be employed. Ceramic cannot be melted down in recycling waste facilities.
What is the distinction between Terracotta and Clay? – Terracotta is clay that has been shaped and fired, whereas clay is a raw substance. Terracotta objects are frequently made of any biological clay, but earthenware clay has the darker color associated with the name. Terracotta objects with low-temperature firing have a porous and permeable surface.
What are the types of ceramics? – Ceramic or pottery may be divided into three categories: Earthenware, stoneware, and porcelain. However, you should read the entire essay since there are a few very interesting differences between the ceramic categories.
What Is Raku Firing Technique? – Raku firing is a low-temperature firing method. During a Raku firing, volatile portions of compounds and molecules in the clay/glaze break away, leaving only free oxygen to adhere to the remaining material. As a result of this, oxides are produced. Oxidation is the term for this process. The oxidation changes the color of the glaze and the texture of your clay. At times, the shifts might be rather dramatic. Read the article to find out even more interesting facts about Raku pottery.
What To Look For And Do For Food Safe Low Fire Clay Products
1. Low Fire Clay Gaze And Food
In The Presence Of Specific Foods, Some Clay Glazes Become Soluble Making Them Not Food Safe
It’s important to understand solubility glazes can progressively release their components into the food that might hurt people who eat it. In acid foods such as orange juice, most glazes leach more rapidly. And some clay glazes can dissolve more rapidly when in contact with alkaline foods such as certain green vegetables.
2. Clay Glaze Color Change
Do not use low fire clay products again if you see glazing that changes color during or after contact with food and drink.
3. Low Fire Clay Surface Irregularities
Some pieces meeting the glaze requirements may still not be safe to use because of the holes in the clay itself, pits, or holes under the glaze. I have seen in holes mold cast mugs where the handle meets the cup body, or holes in the clay under the plates, where the clay was poured into the mold. Seeing these holes and depressions is not unusual.
They may have filled these holes with the glaze or not. If you opt to buy these low-fire clay products, you should take particular care in cleaning them and inspect them for areas where clay may be exposed without any glaze.
5. Low Fire Clay And Your Oven
Do not place low fire clay in a hot kitchen oven. Put the prepared dish in the oven and start the oven for 10 minutes more than the recommendations. Allow the low fire clay dish to heat along with the oven to reduce breakage and or cracking.
4. Low Fire Clay Products And Microwaves
I microwave nothing I care about. But you should be aware low fire clay products with gold, platinum, or other metal decorations are rarely microwave safe.
You can do a test. Place a test piece in you microwave with water and turn on the microwave for a short duration. About 30 second or so usually does it depending on your microwaves power. Then look at the microwave while it running to see if you see any sparks. If you see sparks then you know there is a lot of metal in the clay. It’s not going to be good for microwaving.
Also, carefully check how hot the low fire clay product is. It may be hotter than the water. If that is the case, then it’s not a suitable candidate for microwaving.
6. Low Fire Textured Clays Not food Safe
Textured glazes are not considered food safe. Inspect your dinnerware before purchase to ensure no textured parts come in contact with food. Textured surfaces are not easily cleaned and the glaze may not be durable. No harm may come, but it’s not desirable. Also, anything labeled as Raku is not considered food safe, as the clay product is porous.
Hayes, T. R. (2008). Iron based earthenware in a forced reduction atmosphere. https://soar.wichita.edu/handle/10057/1372
Bond, J. J. (1976). Teaching the Historical and Technical Development of Pottery.