What is it, why is it used, how is it applied*
Ceramic Design Sep 12, 2023
The plate protector protects your oven plates from accidents such as glaze leaking, dripping, and melting mud, and helps you use your oven and oven plates, which are the most important parts of your workshop, for many years without any problems.
What is a plate protector?
Plate protector is a liquid substance that is applied to the oven shelves to prevent ceramic products from sticking to the shelves. The plate protector is made from refractory materials such as silica, alumina or zirconium, which have high melting points and do not cause melting when combined. Its contents are adjusted according to the firing temperature you aim to work with; While silica is typically used in low or moderate temperature ranges, alumina derived from kaolin, the basis of porcelain clays, is generally used for higher temperatures because it has a higher melting point. Zircon is used for high firing programs because this component has an even higher melting point than alumina.
When a rack is properly protected with a plate guard, it can simply be removed when the kiln cools, even if molten glaze spills onto it during firing. If the plate protector is working really well, when you lift the product it will only pick up the top layers of refractory powder, leaving some still on the shelf. Plate protector should be re-applied to areas that have spilled or started to thin. For this reason, it is important that the plate protector is resistant to as high a temperature as possible. Plate protectors that are not resistant to high temperatures may lose their dusty character and harden into flakes, sticking to the bottom of the product, and these pieces may be very difficult to remove. So, among all plate protectors, zircon is a good option as it is very thin and forms a good slurry.
You can make your own plate protector by following the recipes you can find from various sources, or you can buy the plate protector prepared in advance. you can buy.
Why do you need a license plate protector?
The plate protector provides a protective layer between the ceramic work and the kiln shelves. A plate protector should be used in every glaze firing. Even though all precautions are taken to prevent the glaze from coming into direct contact with the oven racks, it can sometimes flow, drip or melt onto the rack unexpectedly. You don’t necessarily need a plate protector when baking biscuits, but some porcelain clays can stick to your oven rack when fired. It is also recommended to use it in biscuit firing as the “feet” of the product may get stuck during the expansion and contraction stages during firing, some porcelain clays tend to stick and there is always a risk of the clay melting.
If you do not use a plate protector, you will damage the smooth surface of your oven shelf, apart from doing laborious tasks such as removing a product stuck to the oven shelf from the plate and scraping the leaked glaze from the oven shelf. Any glaze you miss while scraping will continue to eat away at your oven rack by seeping into the pores of the rack, weakening it. If the weakened oven plate breaks during firing, your oven and all your work in the oven may be damaged along with the oven plate. From this perspective, the license plate protector is a very economical and easy application.
How is the plate protector prepared and how is it applied?
The plate protectors you buy ready-made usually come in powder form. Here are the steps to mix and apply:
one. If you are using new oven racks, it is recommended that you bake the racks once in an empty oven before applying the plate protector. This first step will ensure that any organic material on the baking plate is destroyed. After the first firing, your oven shelves are now ready to apply a plate protector.
2. Mix a small amount of plate protector in a bowl. The consistency of skim milk will be suitable.
3. Apply plate protector in thin layers to the oven rack using a wide paintbrush or roller. If the coating is too thick, it is more likely to crack and peel. Also, be careful not to get it on the edges of the oven rack; It may spill onto your glazed pieces on the bottom shelf during firing. You can also wipe a 1cm area around the plate to ensure it does not extend over the edges of the plate.
4. Apply plate protector in at least 3 coats. Allow each coat to dry thoroughly before applying the next.
5. If the plate protector flakes, be sure to scrape it and clean it. If you notice the plate protector flaking off, remove any loose bits with a paint scraper and reapply. Similarly, if any glaze drips onto your shelf, use the paint scraper to remove it, clean up any loose flakes around it, and then apply some plate protector to the spot that’s left open.
Additionally, you should only apply the plate protector to the top surface of your shelves. If you want to flip your shelves upside down, you’ll need to scrape off any plate guard you used to prevent spills from spilling onto the containers below.
What should be done if the glaze gets on the oven shelves?
If you used a plate protector, you should have no problem separating a product with leaking glaze from the oven rack. When you remove it, the plate protector in that area will come with it, but for the most part you just need to sand the bottom of your product. You can refill space on the shelf with some plate protectors. However, over time the baking plate will become rough from multiple applications.
Continuing to fire on a rough furnace plate may cause ceramic products to deform, crack or break. Therefore, you need to clean the plate protector, which becomes rough after a few firings, and renew it by reapplying it.
Here are some important things to keep in mind when cleaning the plate protector from your oven rack:
Examine your racks carefully before each cooking.
If there is a loose, flaky plate protector on the oven rack, be sure to remove it with a paint scraper or wire brush.
Wear safety equipment.
Wear goggles or a face shield along with a good dust mask, and when scraping, brushing or sanding shelves try to do it outdoors if possible.
Remove any accumulated glaze residue.
Small blobs of glaze can be chipped away with a hammer and chisel, but never hold the chisel perpendicular to the rack. For more serious glaze leaks, you will need to sand the glaze and clean the plate protector.