How to Flocculate a Ceramic Glaze for Better Coverage

Plus, Tips on hydrometers!

how to flocculate a ceramic glaze

Have you ever glazed a piece and had the glaze run off the high points a little too much? Sometimes that effect is desirable, but other times you might want a more even coating of glaze.

In majolica glazing, an even coat of the base glaze is desirable because it acts as a canvas for the decoration. In this post, an excerpt from her video Majolica Decoration: Creating Colorful Surfaces, Linda Arbuckle explains how she tests her glazes and makes sure they are properly flocculated to ensure even coverage. Even if you do not do majolica, this advice can be helpful in other glazing situations. – Jennifer Poellot Harnetty, editor.

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This clip was excerpted from Majolica Decoration: Creating Colorful Surfaces with Linda Arbuckle, which is available in the Ceramic Arts Network Shop!

Why wait? CLAYflicks subscribers can view the entire video instantly when you click here! Not a subscriber? Click here to get a free trial and browse hundreds of ceramics videos!

To learn more about Linda Arbuckle or to see more images of her work, please visit

Plus, Tips On Hydrometers!

Many ceramic artists stress the importance of having glazes mixed to a consistent thickness especially when making incised ware. The purchase of a hydrometer can make all the difference in the world when mixing glazes. In this post, potter Mea Rhee of Silver Spring, Maryland, tells us how to make a homemade, low-tech hydrometer for the clay studio. Whether you go high-tech or low-tech, a hydrometer can help you achieve consistent results when glazing! Do you need to figure out the specific gravity of your glaze? In this post, Roger Graham shows you how to make and use a hydrometer using a simple soda straw!

Do you have a simple, yet effective way to test the specific gravity of your slip, underglaze, or glaze? Tell us all about it in the comments!

**First published in 2012.
  • Shirley Z.

    Hi Linda…Thank you so much for this explanation. I belong to a studio in Toronto, and this summer we had a terrible time with the glazes the owner mixed. It was VERY hot and humid outside, and stifling inside. We all complained to our teacher about the consistency of the glazes and were very unhappy with the results of what came out of the kiln. He said there was nothing wrong with the glazes, and that we hadn’t mixed them enough. I knew that wasn’t true because I had made a point of mixing them very well — and all of us encountered inconsistent results. Your explanation makes total sense to me, and I am certain that, when I tell my fellow studio members, they will be so happy to hear that we weren’t all crazy — and that there is a clear and scientific explanation for why ALL of us were getting such poor results when we glazed our pieces.

  • Christine L.

    Can the addition of Epson Salt mixture impact the results of the fired glazes, especially for raku glazes?

  • I have been wondering about this for a long time and actually swhitched to using commercial glazes primarily for this reason, as well as general lack of time.
    What a great snippet to recieve!
    Thank you for this informative short video.
    EPSOM SALTS =magnesium sulphate, is that correct?
    Faulconbrudge, NSW, AU

  • Denise C.

    Hello Linda,
    Can I use this process with a commercial glaze? I use Amaco LM-10 transparent matt. Until recently, I have had good coverage, but noticed some problems with a recent firing. I have my glaze in a large covered bucket, because I like to mix it just as you described in the video. The next time I am glazing, I will pay attention to how the glaze adheres to my hand. Also, in the mean time I will purchase some Epsom salts, so that I would be ready to de-flocculate my glaze.
    Thank you so much.
    Denise M. Carlin

  • Carmen A.

    I am a beginner but I loved your explanation and am sure I will have this in mind for future use, thanks!

  • Allison M.

    Thank you SO much, I will report back with my attempts to loosen up my cone 5 copper blue, so I don’t have to add as much water.

  • What a great job Linda.
    It is nice to see you and hear you even if it is in the virtual world.

  • Shirley P.

    Linda, I have admired you majolica work, and you have been the catalyst to get me to try the process. I love painting, so majolica makes me heart happy. This video is so clear and concise. You’ve solved a very basic problem for me . . .Bless you.

  • Jewell M.

    That is great information! I will be sure to pass it on to fellow students at our local creative art center. It’s a great tip for celadon glazes that need to have even coverage. Thanks!

  • Lisa S.

    Linda, this was so clear and understandable! As Elsie said, I have some pots I wish to reglaze, and will follow your instructions. Thanks again!

  • Elsie S.

    Thank you Linda! I have some pots which could do with re-glazing and I couldn’t get the glaze to stay on, as they were quite high-fired. I will get some epsom salts tomorrow if possible and see if I can remedy the problem. – there’s so much to learn and I love it! Thanks again!

  • Suzi C.

    Hi Linda…..Just in the nick of time! I am about to start a glaze session and have lost all the notes I made when you were at Haystack in 2002. Could not for the life of me remember how to stop the glaze from running off the edges. I use your ^04 white glaze so this should be perfect. Thanks again……….*s*

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