Beginning Ceramics Part 7: How to Underglaze 

Glad you enjoyed it!

You're welcome! Yep, they sometimes do. As a teacher, I see it often. Some brands are actually more likely than others to shiver off, regardless of how thin they are. I have found the Duncan E-Z to be the best.

You're welcome! Yep, they sometimes do. As a teacher, I see it often. Some brands are actually more likely than others to shiver off, regardless of how thin they are. I have found the Duncan E-Z to be the best.

Often, people apply underglazes to leather-hard clay. This is especially the case when people want to do sgraffito. (Traditionally sgraffito is done with black slip, but often people prefer to use underglaze since it is more fool-proof.) And leather-hard clay is the ideal moisture content for sgraffito. To answer your questions, you should be able to apply all underglaze to wet clay and bone-dry clay. Only some underglazes can be applied to bisqueware (fired ceramics). Getting proper coverage becomes more tricky when applying underglaze to wet clay since you are combating the wetness of the clay. When clay is dry (or fired), it is more porous and acts like a sponge and really sucks up the underglaze, creating good coverage. Therefore, when applying underglaze to wet clay, you will probably have to do extra coats/layers. Traditionally, underglazes were designed to apply to bone dry clay. Some underglazes are still formulated to be applied to bone dry clay only, which is said to create a better bond. So, be sure to read the instructions. If they specify it needs to be applied to greenware and you want to apply it to bisqueware instead, do a test first. Otherwise the underglaze may shiver off if you ignore the instructions and apply it to bisqueware.

I don't buy expensive brushes, especially for underglazes. They wear out so quickly due to the ceramic surface. Below are links to brushes that would be good. I usually go to my local art store and purchase a package of synthetic brushes that contain a few sizes, running around $10-15. They need to have a little spring and I prefer the flat brushes. www.amazon.com/Royal-Bottom-Golden-Taklon-Assorted/dp/B000X1YMNW/ref=asc_df_B000X1YMNW/?tag=hyprod-20&linkCode=df0&hvadid=198061515308&hvpos=&hvnetw=g&hvrand=17456212808989843091&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030901&hvtargid=pla-297145077811&psc=1 www.dickblick.com/items/blick-scholastic-short-handle-golden-taklon-brush-set-flat-wash-set-of-4/ www.amazon.com/Royal-Langnickel-Crafters-Choice-Variety/dp/B008BSYCQ6/ref=psdc_12897541_t1_B000X1YMNW

@@rebekahbogard3322 Thanks so much for the info and links.

Can you please show the picture the final outcome, of the butterfly?

@@dhivyarajasekaran7159 I really rushed this process and did not do a very good job of application. So, I don't think I fired it.

3M Automotive Refinish Masking Tape. I was using size 233+. The thinner the tape, the easier it is to bend. I try to buy directly from 3M, but I suddenly can't find it on their dumb website. But you can buy a variety of sizes of the same thing from Amazon. www.amazon.com/dp/B09BQWVSGT?th=1

Some people really like the crazing. But it is frustrating when it happens and you don't want that result. Your glaze is crazing because the glaze does not fit the clay body properly. This may be due to the bisque temperature, or the type of clay body you are using. Be sure to read the instructions on your glaze if you have not done so already. They usually say to bisque your piece to 06 and then glaze to 06. But this varies from brand to brand and glaze to glaze. If you are bisquing at a different temperature, this could be the source of your problem and causing the crazing. But if you are following the instructions and you are still having crazing problems, it is your clay body. (FYI, I often bisque to cone 04 or higher and then glaze to cone 06 and I never have a problem with the Duncan clear glazes crazing on me) If your clay body is a high fire clay body and you are using low fire glaze, it will sometimes craze. So, you would need to switch your clay body to avoid crazing. Or just donate your glaze to a local pot shop. You may find a different brand of glaze that does not craze on your clay body. So, I would just experiment. Hope that helps!

No, you do not need to fire the underglaze onto the piece before you apply clear glaze. Traditionally you apply the underglaze, wait for it to dry, then apply the glaze, and then fire it. I sometimes apply the underglaze and then fire it because I want to leave open the option to add more underglaze to certain areas if I am dissatisfied. Then fire it again. If it looks good, then I apply the clear glaze and fire it one more time. It is important to note, the more times you fire the piece, the more likely it is to crack. So I try to minimize the amount of fires a single piece goes through. You also run the risk of applying your underglaze too thickly with this approach. Look at the instructions on the label for firing temperature. Almost all of them are cone 06. But not always. So, you need to read the instructions.

@@rebekahbogard3322 thanks you !

After applying underglaze, you may apply clear glaze directly on top of the underglaze. Just make sure the underglaze is completely dry before applying clear glaze. And, make sure you have a light touch when applying your first coat of clear glaze. Otherwise, you could smear the underglaze in the process. And then fire to cone 06. Some people actually fire the underglaze before applying the clear glaze to avoid messing up the underglaze. And then they would send the piece through a third and final firing. I suggest practicing on a test tile first to see how well you are able to apply the clear glaze on top of the underglaze without smearing it.

Underglaze will show through a translucent glaze and obviously a transparent glaze. For example, Duncan has a line of glazes titled Envision, many of which are translucent colored glazes. Therefore, if you used yellow underglaze and covered it with a translucent blue glaze, after it is fired, your color would be some shade of green. This is a useful trick. To exploit this trick, when using a white clay body, you could mask out polka dots and apply three coats of yellow underglaze. Once you have applied all three coats of your yellow underglaze, you would remove the masking tape to reveal the white clay body underneath. Then, you could use a translucent blue glaze over the entire surface. After fired, your yellow underglaze would appear to be green (yellow and blue make green), and then what was once white polka dots would be the translucent blue glaze.

@@rebekahbogard3322 thank you for the reply!

I imagine you could use underglaze on top of glass and fire it. But I have never done this. I would be concerned that the glass you have may melt in the kiln since I assume you do not know the chemical make-up of the glass and therefore do not know it's melting point. So, if you really want to do this, I would do a test firing of the glass first to make sure the glass can withstand the temperature. Otherwise you may have a disaster on your hands and potentially ruin a kiln, at the very least, ruin kiln shelves.

Non parlo italiano. Magari attivare i sottotitoli/sottotitoli?