Tenyoh

It seems high absorbent clays are not ideal for most of the functional ware (provided there are wet wool ). I'll keep that in my mind from now on. Mark C, I am considering to mail-order Laguna clay. All I need for now is a box. That should work. Thank you all again for your input.

Besides seeping, what else problems do you anticipate with absorbent clays? I was going to make something like yarn bowls and spoon rests with that clay.

Glad I can access to this forum today. I did the tests suggested by you. Re: Crackles A test with Epsom Salt did not work (I dissolved the salt in hot water and then added an equal amount of vinagar), but it worked with lime stone. Crackles I saw were so superficial that they disappeared once I wiped the powder. They must go zigzag through the glaze all the way to the clay surface. Hopefully a 10-minute hold will solve this problem. Re: Vitrification I tested with an unglazed chunk of clay that had been fired to cone 6. The absorption level was 4.4%. Percolator, you recommended to fire the clay to cone 7. I wonder if it's worth trying it, knowing the clay mixer's suggestion of glazing inside. As I want to leave my vases unglazed like some of you are doing, I'm thinking of trying clays from an established clay manufacturer. Have any of you used Laguna's, especially the following brown clays: WC394 SB Red, absorption 2% WC420 Redstone, absorption 0.5% WC866 Electric Brown, absorption 0.5% As I have to drive 5~6 hours to get to the nearest Laguna distributor, I intend to purchase a few different ones and experiment with them. Thanks again.

Thanks for the ideas for the household item substitutes. I have toothpaste and epsom salts. I'll give them a try. You all are with full of ideas and expertise. I feel heartened. Thank you so much.

Thank you, MathewV, for the info. Yesterday I epoxy-glued decorative feet on the bottom of the vases and then tested for the weeping again. (As I had anticipated the problem, I had made the feet at the same time with the vases.) Ventilation of the dry South Dakota air seemed to have helped. The bottoms felt cool to touch, but not wet this morning. I put small pieces of folded paper under the vases between the legs, to see if it will get damp by this evening. I learned a lot in this post. Thank you very very much. I don't have Whiting. Do you think I can substitute it with baking soda? Mixing it with vinegar will certainly bubble.... It may be fun to test it. Thank you for the info.

The clay manufacturer's catalog does not even list the absorbency of clays they sell. Yes, I will look for another supplier and test the clay as Min suggested. Thank you very much. Douglas, I tried this method using ball clay. I may have used too much clay. When I dumped the water, it left streaks and lumps and it was difficult to see fine cracks. Thank you for your suggestion, though.

Thank you for your responses. As Mark C.'s answer was interesting, I called the clay manufacturer. They said even though the clay had the broad range, it should not affect the vitrification. "Even cone-10 clay will seep after awhile." "You have to seal with glaze." Their answer confused me about the vitrification. They recommended to hold the kiln for 10 minutes to seal the crazes and pinholes. Even though I don't see them, they must be there. MathewV, have you experimented with holding the kiln?

I'm making ikebana vases and having a problem with water seeping out the unglazed bottom. As I thought the clay vitrification was the problem, I fired the second batch one cone higher - to cone 6. (The firing range of stoneware I used was cone 06-6.) After the firing, I poured water into the vases and waited overnight. To my disappointment, water still weeped through. I read in your former topic, "If the glaze crazes, then liquids can seep through the cracks in the glaze and into the wall of the pot, and weep out the unglazed bottom." Amaco Potters Choice glazes I used do not look crazed, but it must have been. Are there any special way to glaze inside a vase, so that it will not craze? (I put a tiny bit of water into the glaze and spread it inside the vase.) Do you recommend any particular commercial glaze for this purpose? Does glazing the bottom slow the seeping significantly? So far, I've been solving the problem, sealing the cracks with liquid waterseal for wood. However, I worry the effect may last only temporarily. Do you have any idea how long the effect of such sealant will last? Thank you for your expertise in advance.

bciskepottery, thank you very much for the link. I was able to access it this time. Fred, it sounds like I just have to experiment. Thank you very much.

As I try to mix my own washes. I found this old topic useful. What kind of flux do you recommend to mix with oxide, water, and ball clay? I usually fire my sculptural works to ∆06~04 and functional ware to ∆5. I'm hoping to use the washes for both purposes. Does frit-3134 stay matte at low temperature? The above website no longer exists. If you know any other sites that beginners could learn about oxide washes, I will appreciate it. I've been using Mayco rutile wash, which fires from ∆06 to ∆11. As my supplier does not carry it, I'm hoping to make my own. I'll appreciate your help.

Thank you for the response, Douglas. The firing range for raku clay I've been using for sculpting is cone 06 to 10. I see your reasoning why the slip did not join clay bodies well. I have a tiny bit of earthenware clay (cone 06-02) left. If I make slip with it and use it to join two raku clay parts, do you think they will adhere better? I stopped using the earthenware because it just did not feel right in my hand. I join pieces at leather-hard or usually earlier stage, but it's good to know we can use sodium silicate as a temporary glue.

Adhering with glue after firing seems an answer for this type of problem. Thanks, Chris.

Thank you, Marcia and bciskepottery, for the info. I will experiment the recipes and post the results on this site.

Thank you again, bciskepottery. I agree with you that barnard clay probably needs mid-fire temps to adhere well. May I ask you basic questions? Can the borax mentioned in your recipe be 20 Mule Team Borax, which is Sodium tetraborate? I suppose gerstley borate and frit 3134 are sold only in ceramic stores, right? If so, I have to order them online. I googled "manganese dust." It's not only hazardous to health, but also flammable. I will make sure to wear a mask and goggles when handling barnard clay.

Thank you for responding to my question so quickly. My slip is straight barnard clay. I'm such a beginner I've never experimented with a flux. Could you please share a recipe with me? By adding a flux to the slip, does the finished appearance change? I could try applying the slip at the leather-hard stage for some simple figurines, but for complex ones, I would like to bisque-fire them first.