When the Kiln Lid Flakes...


Great information about kiln lid repairs from our friends at Paragon...

At Paragon, they coat the inner lid surface of all kilns to reduce brick dust. Sometimes the refractory coating is too thick so, it will blister and flake off when the kiln is fired. An especially thick coating looks like a network of peeling cracks similar to a dried mud puddle. This cracking is due to the difference in expansion between the firebricks and the coating. Conversely, correctly applied kiln coating will look like it disappeared after the kiln has been fired.

The good news is that cracked lid coating is easy to repair. Just lightly remove the blistering coating with sandpaper and apply a new coat of liquid kiln repair cement. Keep in mind that the natural tendency is to apply too much lid coating because it just looks better than a thin layer.  If done correctly, you should still be able to see the firebrick pores under the coating!

First, shake the container very well! Then, pour some of the coating into a bowl. Make sure to stir it just before you apply it to the firebricks. Apply the coating with a large, soft sponge. Moisten the sponge with water; then squeeze out the excess... this is a very important step! Dip the sponge into the bowl of kiln coating. Wipe the coating over the lid surface.

Do not let excess coating run into the element grooves of the kiln. Applying a light coat will prevent this from happening. If the coating drips along the edges of the grooves, remove by wiping a cotton swab or rag along the groove.
Many people have asked us... "What is the difference between kiln cement and Liquid Kiln Coating? Can a lid be coated with a thin mixture of kiln cement?" The answer is YES! Kiln cement thinned with water will work as a lid coating. Liquid Kiln Coating is simply a mixture of kiln cement, fine brick dust, a gumming agent, and water.

The great news is that lid coating lasts for several years. So, it's not something you need to worry about on a daily basis.  But, if you start getting kiln brick dust on your work, maybe it's time to re-apply. 

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