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      Ceramic Arts Network is looking for two new forum moderators for the Clay and Glaze Chemistry and Equipment Use and Repair sections of the Ceramic Arts Network Community Forum. We are looking for somebody who is an active participant (i.e. somebody who participates on a daily basis, or near daily) on the forum. Moderators must be willing to monitor the forum on a daily basis to remove spam, make sure members are adhering to the Forum Terms of Use, and make sure posts are in the appropriate categories. In addition to moderating their primary sections, Moderators must work as a team with other moderators to monitor the areas of the forum that do not have dedicated moderators (Educational Approaches and Resources, Aesthetic Approaches and Philosophy, etc.). Moderators must have a solid understanding of the area of the forum they are going to moderate (i.e. the Clay and Glaze Chemistry moderator must be somebody who mixes, tests, and has a decent understanding of materials). Moderators must be diplomatic communicators, be receptive to others’ ideas, and be able to see things from multiple perspectives. This is a volunteer position that comes with an honorary annual ICAN Gold membership. If you are interested, please send an email outlining your experience and qualifications to jharnetty@ceramics.org.


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Everything posted by Les

  1. damp plaster

    See the attached file for my mixing chart. Open as an Microsoft Doc....This should work. Good luck, Les #1 Plaster Mixing.doc #1 Plaster Mixing.doc
  2. damp plaster

    See the attached file for my mixing chart. Open as an Excel Spread sheet....Les
  3. damp plaster

    Sorry about my post above. It is a nice Excel spreadsheet for mixing plaster that this system is not set up to handle. I'll try to post in a different format. Regards, Les
  4. damp plaster

    For a specific reply to plaster ratios & water needed: for No.1 Pottery Plaster, the ratio is about 70% water (by weight) to plaster. I have attached a chart below that I use not only for mixing, but for figuring out the right amount to use for the volume I need. The ROUGH RATIO IS 3 POUNDS PLASTER TO 1 QT OF WATER, as stated below in the chart. After I get everything set up and ready to mix, I hand strain the plaster into my mix bucket using a wire mesh food strainer. The process is quick, but gives the plaster a good chance to be absorbed by the water without creating lumps or clumps. After that, I will always mix slowly with a latex gloved hand, just to make sure all lumps have been eliminated.....Good luck on your next project. Les PLASTER MIXING CHART FOR #1 POTTERY PLASTER VOLUME WATER WATER PLASTER CREATED IN IN IN POUNDS (CU. INCHES) QUARTS POUNDS (70% CONC) ONE GALLON= 4 8.33 ONE QUART= 1 2.08 3.0 80 1.0 2.08 3.0 88 1.1 2.29 3.3 97 1.2 2.52 3.6 106 1.3 2.77 4.0 117 1.5 3.05 4.4 129 1.6 3.35 4.8 142 1.8 3.68 5.3 156 1.9 4.05 5.8 171 2.1 4.46 6.4 189 2.4 4.90 7.0 207 2.6 5.39 7.7 228 2.9 5.93 8.5 251 3.1 6.53 9.3 276 3.5 7.18 10.3 304 3.8 7.90 11.3 334 4.2 8.69 12.4 368 4.6 9.56 13.7 404 5.1 10.51 15.0 445 5.6 11.56 16.5 489 6.1 12.72 18.2 538 6.7 13.99 20.0 592 7.4 15.39 22.0 651 8.1 16.93 24.2 716 9.0 18.62 26.6 788 9.8 20.49 29.3 867 10.8 22.54 32.2 953 11.9 24.79 35.4 1049 13.1 27.27 39.0 1154 14.4 30.00 42.9 1269 15.9 33.00 47.1 1396 17.4 36.29 51.8 ROUGH RATIO IS 3 POUNDS PLASTER TO 1 QT OF WATER
  5. Hi everyone, While teaching a class how to make plaster press molds of tiles, everyone wanted to know the best clay mix to use to prevent warping during drying and firing. I currently use a medium grog red sculpture clay for midrange firing. More detail-- most tiles are about 4x4' and I suggest about 3/4" thickness similar to the way Grueby made their tiles 100 years ago. Does anyone have any suggestions on best clay, methods, or brands that they have used with success? Thanks, Les
  6. Marko, Thanks for yor reply. So, I usually dry my tiles just as you suggest. I use 1/2" Sheetrock and dry for at least two weeks, slow and steady, no rush at all. By the way I'm located in the New York area and my clay is from Ceramic Supply out of Lodi, NJ. The clay is a S108 clay that fires in the C4-10 range. But, from what you're suggesting, the trick is almost entirely in the slow drying, and has very little to do with the type of clay used. I appreciate your input Marko. My thanks again, Les
  7. Hi Everyone, I usually throw one off pieces. But I have 2 already bisqued pieces that I would like to try to make molds from. So my questions are: 1) Should I glaze them first? 2) What mold release is the best to use in either the bisque case or the glazed case; from the point of view of both the originals and the #1 pottery plaster mold. Facts: No undercuts on the originals. Both bisqued pieces were made from Standard Clay #240, smooth white, ^6. I plan to have a 2-piece mold for the vase itself (no foot ring), and a third top piece to serve as a slip reservoir. I make great plaster, having experience with press molds for tiles. Has anyone been in this situation with good outcomes? Could you share your success, or failure, as the case may be? Any thoughts are appreciated, Les
  8. Charles, Thanks for your reply-I will try casting the bisque pieces, and good idea to incorporate the reservoir into the 2 part mold. Les
  9. Mold On Drying Tiles?

    Bisque firing of the tiles will burn off the mold and have no adverse effect on the them. Let the Sheetrock dry vertically and wipe the mold off with a dry cloth. The Sheetrock will look a bit stained, but can be used many times again. If you are mold sensitive, don't use this method for drying. Try a rack open on the bottom to allow even drying at the same time on both top and bottom to avoid warping. At Home Depot, Lowes, etc, in the lighting section you can find a 2'x4' light diffusing grill that is made of tiny open squares. Resting on open metal shelves, this grill gives good support for drying tiles evenly. You can cut the plastic grill to fit open metal shelving. Les
  10. I have used PC-2 Saturation Gold many times. In the studio, I will always use it over or under another PC glaze, and some of the results are stunningly beautiful. We fire at cone 5 oxidation, and I have had some great results. Strangely, I have never gotten a great result using it alone, where it tends to come out with a dark matte metallic look, not totally gold, and not high gloss or smooth: a bit on the ugly side. I guess I haven't found the secret yet to using it by itself. I must be doing something wrong. In any event, I suggest you do a lot of testing on your clay body with the gold before actually using it. Good luck, Les
  11. Hi everyone. I'm currently working on some arts and crafts forms and looking for a Grueby green / Cucumber green formula that is suited for ^6 oxidation. I would appreciated any suggestions at all. I can't seem to find a clue to this formula on the internet. Anyone out there have experience in this area?? My thanks for any help that can be offered.
  12. Thank you for your fast reply. I obviously missed your post first time around. The picture looks very good.
  13. I also use the water based latex wax resist from Ceramic Supply. I think it does a good job. I apply it fairly fast with a clean brush. Dampen the brush first, before the first dip into the resist. Both the rim of the jar and brush will start to air dry fast, and the jar will start to form small clumps from exposure to the air, so I suggest pouring off what you think you will need into a small plastic cup, then clean the rim of the supply jar with a sponge and reseal it quickly. Keep your brush moving, and add a bit of water and remix if your cup starts to thicken. I would advise disposal of the cup and its remains after use. Do not pour back into supply jar (hopefully you wont have too much left). Also, this may be obvious, but try to do a lot of pieces at once. Clean the brush with soap and warm water after use.
  14. I have used Amaco's Bisque Fix and can verify it works very well. I have even used it to repair green ware by mixing it with a small amount of slip for a color match with darker clays. It dries rock hard and fires well. Just follow the instructions, and do not sand or inhale. Use this link to view: http://www.amaco.com/shop/product-322-amaco-bisque-fix.html
  15. Tile Making With Mold

    I make my molds and use the exact same process as "tluvs2create", and I have had the same problem several times. I never found the absolute answer to this, but I changed my process a bit and got better results. First, I cut a template for the tile blank slightly smaller than the mold walls. This allows the blank to be dropped into the mold carefully, without hanging up along the mold's outside walls. I then gently press down slowly with my thumbs from the center of the mold outward, to ease the blank evenly towards the walls and corners, making sure not to trap air between the tile blank and the mold. After that, it cover the top of the clay with canvas, and start pounding away with rubber mallet and a strong wood bland (2x6 usually), no bigger than the mold itself-but it must cover the entire tile area. My original tile is typically 3/4" think before casting, so the mold is 3/4" deep at the edge. I use a smooth blank that is about 1 1/2 thick. I wire away most of the excess clay on the first pass, then do the final cleanup with a wooden straight edge. I agree that a press mold, a converted customized arbor press, or a small hydraulic press is best, because of the steady even pressure they can apply. If you are serious about using press molds, this is the way to go. That will be my next step. Although I throw on a wheel, and hand build, I am hooked on the process of press molds as well. Good luck!!
  16. I agree with Deb Evans. Whatever tools you use, either a router or jig saw, use a variable speed to slow the cutting/sawing down, so you are not remelting the Poly material. Clean up with a sharp Xacto knife
  17. Thank you Steve, so much. I was the poster that lamented the lack of any manufacturer's help, but you and Amoco proved me wrong. I can't wait for your pictures to arrive. In the mean time, I am going to purchase another pint of Ancient Jasper and follow your suggestions. I'm looking forward to good results. For the record, I am a big fan of the entire Amoco PC line, and highly recommend them for potter's that work with glazes "out of the jar". Thanks again.
  18. This may sound too simple, but instead of trying to figure out the glaze chemistry,etc. (endless work); just go out out and buy a different brand of the black, cobalt blue or iron red, and see what happens. For some reason, those colors may have a chemical in them that doesn't work well under your current conditions, so the most simple plan of attack is to try another brand.
  19. I have found Amoco's Saturation Gold works well as the first of a two layer combination of glazes. Use it almost like an under glaze, with the second glaze being somewhat translucent, to allow the gold to filter through and be seen. This is a glaze that you need to experiment with. Using it alone at ^6 oxidation in an electric kiln will not get good results.
  20. Try Amoco's PC 59 Deep Firebrick. I use glazes besides Amoco's, but find their PC line stable and dependable. I fire at ^6 oxidation, and if it matters, I'm a male who finds this red has a nice deep hue to it. http://www.amaco.com/learn-about-potters-choice-glazes/
  21. I have used this glaze twice, each time at ^6 electric oxidation, and both times it has produced a muddy brown color. I did notice the red starts to come out where the glaze has been applied thicker. None the less, I was disappointed in it and don't intend to use it again. After all, how many bisque pieces can you afford to lose? It would be nice to have a glaze techie from Amoco chime in on this. Do you think they read our comments? I sure hope so. It would be nice if all the suppliers actually tried to help point us in the right direction every once in a while. This glaze is new, so perhaps we'll hear from them.
  22. Glaze Application Problem

    I've had this problem a few times, and remember reading a solution that seems simple but effective. I't doesn't involve glaze chemistry, kiln firing temps, etc. Here it is: Do not apply a thick coat of glaze all at once. If you're either dipping or brushing, apply a normal coat, and let it dry completely, in most cases 24 hours. Then you are ready to dip or brush the second coat, to add to the thickness of the glaze. Also, to insure the at the first coat bonds well, a fast dip in water to dampen (not wet) the bisque will help suck in and bond that first coat, but then let it dry 24 hours before the second coat is applied. This shoulod minimize flacking

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