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Hi all, New here as a ceramic arts daily member, but i have been browsing this forum for great info for years! I am currently trying to make an outdoor sculpture for a project I am working on in architecture school. I am thinking about using Hydrocal® White Gypsum Cement to create my sculpture because of its durable qualities and hopefully easy to finish nature (please feel free to advise me if I am right or wrong on these, I am new to working with the material). The question I have involves casting the Hydrocal to create the sculpture. I am thinking about creating a hollow clay coil mold for my sculpture, into which i would pour the hydrocal mix to allow for it to conform to the coil mold's interior shape and form. I would pour-cast this sculpture as the clay mold (laguna bmix) would be in the leather-hard shape. To limit the weight of the final sculpture, I would want to let the outer portion set up and be able to pour a significant amount out, so the final hydrocal sculpture itself is hollow too. Does this sound like it would work? I am worried that the hydrocal would stick to the clay mold, or that it would be too thick a consistency to pour out to make it hollow. I hope that this makes sense to you all. Please respond with whatever feedback you think that i need, with whatever information you could offer me. I appreciate all the help! -Daniel

I have a bucket of old porcelain casting slip that I made a couple of years ago, and I'm wondering if I can reconstitute it. It's pretty chunky, it was originally deflocculated with Darvan 811. Can I get it back to a proper consistency for casting? Should I add more Darvan? Also, does Darvan expire?

Hi all! The company we work with that formulates our slip is having difficulties achieving the necessary properties for casting. The issues are due to the fact that they are taking a plastic throwing body, and are trying to convert it into a casting slip. Due to the fact that we have little control of that formulation, I do not know the exact recipe for the slip. We are just curious how difficult it is to create a Mid-Range Red Casting Slip that is properly flocculated, and casts evenly with no issues. After firing, the color we are trying to achieve is a Red-Orange, preferably something that withstands thermal shock since we are creating drinking vessels. Does anyone have any recipes, or reasons why a high-iron casting slip acts weird? Thank you all for your time!

I'm a figure sculptor who has worked in the past in direct-terracotta (http://haneebirch.org/artwork). I have a new body of work I am in the process of putting together, and for practical/economic reasons I am going down the road of mold-making and casting instead of direct work. Unfortunately, this usually means moving from terracotta to plaster (or worse, plastics and the like). I don't mind plaster but it's hard to touch up and doesn't have much value to most people -- ends up needing a patina, etc. So... What I'd like to do is find out how to cast terracotta figures as was commonly done in the 17th and 18th century. All my catalogues of figure work from that time period always refer to cast-terracotta being fairly common. But, nowhere in modern method books have I ever run across anyone who seems to see such an undertaking as even conceivable. Take this figure by Clodion for example, in the Met's collection: http://www.metmuseum.org/art/collection/search/200559 So, I do have some experience with mold making, but I've never been the greatest mold making. I seem to be competent at waste molding (except I've never gotten a great release agent recipe that really works consistently, seems like sometimes I get lucky and have perfect release, other times something in my application process must fail), and am capable though not exactly confident with my brushed on silicone molds. In my limited mold knowledge I am guessing this peice by Clodion was press-molded, in a multi-part piece mold. Still, it's hard to comprehend how exactly that would have been done, with the bird wings and many undercuts. For myself, my figures are fairly unadorned but the poses are still complex. I can imagine that I could ignore many of the undercuts, cast a rough form, and then I could easily clean it up, add depth, put the undercuts back in. But still the piece mold for a basic figure of non-trivial pose (say, http://haneebirch.org/artwork/chair-no-1 seems beyond my comprehension). Even chopping the figure into separate parts and re-attaching doesn't simplify it all that much, and I'm unclear on how exactly that would be done anyway. So is there anyone who would know of any book or person that could describe all the technique needed to press-mold or slip mold that Clodion figure or the figure I referenced of my own? Is there some alternative technique that I am not aware of that makes this all a simpler proposition than I thought? I have tried press-molding in a silicon mold, and, to some degree, it worked, but how to cleanly joint the pieces and how to control for moderately even drying seemed unclear (though perhaps with enough experimentation). Anyhow, before trying to blaze my own path with modern materials, I'd really ideally like to find a source who can make entirely clear how exactly this was commonly done in the 18th century. Thanks in advance for any information.

Hi everyone, Hope you all have had a good holiday weekend. I have a quick question regarding warppaged and drying of porcelain slip casting. I have a couple of plate moulds and I would like to cast using porcelain. Does porcelain slip warp? Should I follow the same rules for plates regarding drying slowly and upside down? Thanks. Enjoy the rest of the day. Andrea

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Hi all, I am trying to figure out how to make figures reminiscent of Staffordshire pottery, such as the following (sorry it's so big): Apparently these were made using press molds. But I have no idea how the original was made and cast. I bought Plaster Mold and Model Making by Chaney and Skee, but I still don't feel any closer to figuring out this fundamental question. For example, is the original made of clay and then cast before firing? (Obviously, something like the above piece would need several molds in order to create it.) Or were the multiple pieces fired first and then cast? If so, if the parts were thicker than an inch, were they completely dried before firing and then fired at a low temperature? (If this is the method you would recommend, what temperature do you think would be safe to go to?) I found the following very interesting site of an artist working in this old style, but she is using oil-based clay, and somehow I don't think the Old English potters were using that: https://porcelainmenagerie.wordpress.com/ Anyway, if anyone has any info on this (books, advice, etc.), I would be ever so grateful! Thanks in advance, Havely

Hello there everyone! First post from a porcelain newbie. Tell me if I'm being ambitious here, though I'd like to undertake a process of creating many super thin 15-20cm long porcelain feathers for a project. I've only ever worked with stoneware, handbuilding with slabs and pinch pots, I've never used slip before - so this will involve a lot of first time experiences for me. I'm trying to plan out how I'll make these forms, preferably double sided. I have access to a kiln a few months from now, so will be able to do some home experimenting (though I'm a total novice in that regard, so I'd probably want to fire them with my local studio instead - however they only do mid-firings, so not sure if I'd be able to) Regardless, I'm happy to make the greenware and store them until I can get access to a kiln. So here are my ideas, let me know if they spark anything in your mind and you can give me any advice/tell me that it's never going to work First idea: On a dampened plaster slab, using different nozzles on slip trailers, I pipe out the stem and an outline of the feather shape, with none of the feather 'prongs' (?) touching each other, leave to dry for a few minutes: (Sorry in advance for my terrible MS paint skills) Once the first piping has dried a little, I pipe out a second layer of 'prongs' and repeat this process until there are no gaps to achieve a 'feather like' texture: I then finish it by piping out another stem on top. Leave it on the plaster slab to dry, then peel off? Second idea: Buy feather silicone moulds used for cake decorating and create plaster slump moulds from them: The trouble with this idea is that the feathers would only have texture on one side, do you have any ideas on how I could make double sided versions? Third idea: Scrap using slip and use a plastic porcelain instead, roll it out thin and cut out leaf/feather shapes before applying a texture to each piece. (Time consuming?) -------------------------------------------------------- Ultimately I'd like to make 60-70 pieces to start with - and maybe more in future if it all turns out well, so efficiency is important to me. I like the first idea the most since it would make every piece unique, though if you don't believe it would work, let me know as while I'm happy to experiment, everyone's previous experience and knowledge is a fantastic gift and it'd be a shame to waste it

Evening all, Quick question - Can you recycle slip cast mistakes?

Hello everyone! Another question from me: is it possible to cast a flat plate (without a foot) with a one-piece plaster mold? I am usually throwing a prototype with a simple white clay on a wheel, then wait until its dry enough and cast a mold, but when i tried making a plaster mold for a flat plate, plaster seemed to heavy for the clay to hold, clay got softer and caved in. As the result: the mold is with a little knob in the middle. Any advices? Thank you! Nata

Hi, I am having problems with some plaster slip- casting molds that I use regularly. I made the molds in March this year and suspect I have cast into each around 30 times. Over the summer they have sat unused for two months in a dry cupboard. I have gone back to use them and I'm finding the casts are now more reluctant to pop out. They seem to be sort of sucked in there and the plaster doesn't want to release the cast. They are five part molds and sometimes just one side seems to stick on, as if it can't take the moisture out of the slip - even if the rest of the cast is relatively dry. The casts will come out in the end but they are taking longer than before and I risk ripping the casts when removing them. Does a mold have an expiry date? Could there be anything I could treat them with? Please help! Thanks, Elle

Hi, I have recently been experimenting with converting a few of my production pieces to slip cast pieces. I took a Hiroe Hanazono workshop at Arrowmont, ( excellent BTW ) and learned the basics of slip casting. Since then I've made molds of my pieces and have cast several of them. Everything is going swimmingly except... My work is all in a red clay, I use RedRock from Highwater, fire it to a hot 5 / cool 6, I have made a slip from RedRock by drying then adding 40% water and .3% Darvan 811. The problem that I'm getting is that my slip keeps gelling up. I've already got over the maximum amount of deflocculant in it, and have had to add water anyway bringing my specific gravity down to 1.6 instead of the desired 1.75. It's working, but still gelling, I assume from the Iron in the clay. Does anyone have a good cone5/6 red slip for slip casting recipe? I don't mind if it is speckled or not, and it doesn't have to match red rock exactly, just be red. I appreciate any input ! Thanks

I'm using mason stain for the first time to create a black slip. Currently I'm at 5% with 6600 black Mason stain, and my casting body is barely gray after testing. I'm doubtful that another 5% will do the trick. A friend recently suggested that Ferro stains have a higher saturation, that they seem to be more concentrated, and that a person generally has to use less for the desired result. Does anyone know if there's any truth to this? And what stains do you prefer and why?

Hello Everyone, I'd like to start by introducing myself. My name is Ed and I'm new to the ceramics business. Literally all I know is what I've googled so far. What I'm trying to do is find the best method to mass produce stoneware ceramics. I wanted to get everyones opinion here on it. I would like to be able to create up to 10,000 small yet complex pieces a month or more from a few different designs. From what I have read there is the slip-casting method of creating a mold and then using slip to pour into the mold and wait for it to dry and then glaze and fire the piece. The problem I see with this method is I don't think I could reach the quantity of pieces I would like with slip-casting all by myself working full-time or with the help of 1 or 2 people. Another method that I've read about is ceramic injection molding. With this method it seems like I can meet the production goal of 10,000 pieces or more. I was wondering if anyone has made stoneware with ceramic injection molding? If anyone has experience with CIM could you shed some light on the costs involved in the process. Also if there is another way that would be better than anything I mentioned please let me know. Thanks Ed