Terracotta casting slip recipe

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Terracotta casting slip recipe

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All Articles. This article helps you understand a good recipe for a red casting body so that you will have control and adjustability. In North America there is a raw material that makes the creation of a low fire red casting body very easy. It is called Redart. This clay is air floated, high in iron, low in soluble salts and matures at a low temperature around cone 1. In addition Redart deflocculates very well.

Adding iron oxide to a clay causes it to gel badly on dispersion however the natural form of iron in Redart does not do this at all. To use the casting process efficiently you must understand how deflocculation works. Believe me, if you are new to casting and have never mixed a heavy casting slip with low water content you will never go back to a simple clay water mix again after you learn the deflocculation process see the link to an article on this.

At cone 06 almost any mix not containing expensive fluxes is going to be non-vitreous and highly porous.

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However by 04 this figure drops dramatically. By cone it is possible to have stoneware properties in most terra cottas. This is because natural red clays contain so much flux. Consider some of the considerations you must think about when formulating a terra cotta casting body. Body color is usually important, people want the deepest possible shade of red in their terra cotta. This is not a problem for white bodies since you can couple it with white burning plastic ball clay.

terracotta casting slip recipe

But for red bodies it is a challenge because there is not enough room in the recipe for flux given the amount of clay needed to achieve workability the lower plasticity red plus the ball clay.

This means you have a tug of war between color, fit of commercial glazes, maturity and workability. An obvious way to ease things is to formulate your own glazes, this enables removing the talc completely. As mentioned, you cannot just add iron to a white burning clay to get terra cotta color since iron causes slip to severely gel.

In North America the primary red clay used in terra cotta bodies is Redart. It casts very well but it is just not plastic enough so you may need to augment it with ball clay to create a slip that has adequate dry strength and shrinkage to pull away from the mold.An insight into Darwen Terracotta's process, from site survey, to terracotta and faience production, through to delivery and logistics.

Generations of dedicated artisans have passed on their knowledge and experience which enables us to continue providing the best quality and service to our customers.

The manufacturing process has changed little over time, though we combine our skills and experience with the latest modelling, casting, drying and kiln firing technology.

We are always pleased to meet clients, architects or contractors at the earliest opportunity to discuss and advise accordingly. With the technology today we often give general advice from photographs but when necessary we visit site and view the condition of the existing terracotta to determine the best approach forward. Dependent on the information available we can prepare either budget or firm quotations.

We welcome working with you to develop proposals and contract programmes, and becoming a true partner who understands construction demands. Upon instruction to proceed, each project comes under the immediate control of our Contracts Department who will coordinate all design and production matters with the relevant parties throughout the duration of the contract until final delivery and completion.

Our specialist fully safety trained survey teams both in the UK and US will visit site to take all necessary dimensions and profiles of units to be replaced. We have experience of surveying from scaffold or mobile platforms.

Our specialist survey teams will produce shop drawings of each individual piece and where required will send to the customer for approval.

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Elevation layout drawings are produced to show the location of replacement blocks, to assist the installation on site, all in accordance with your requirements. Working with a blend of the finest refined clays from the renowned European ball clay deposits.

Slip, Robin Red Terra Cotta

Material properties are tightly controlled at the manufacturing stage to meet exacting requirements and ensure high quality standards are maintained. Samples will then be submitted for approval. Models are CNC produced in polystyrene, formed oversize to allow for the natural clay shrinkage, from which a reverse plaster mould is made in the traditional way.

The mould can be relatively simple or very complex dependant on the piece. Moulds are dried in dedicated temperature and humidity rooms to ensure optimum production performance and dimensional consistency.

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Our team of craftsmen work closely with our design and survey team, to ensure all models and moulds are produced in line with site demands. We offer a range of casting techniques. The clay is mixed in house with colour and conditions to suit the requirements of the particular project.

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We only use virgin European clays giving us an industry leading level of control of dimensional accuracy and consistency.I have purchased a blunger to mix 30 gallons of slip and hopefully mix a 55 gallon drum with it in the future.

Mainly the goal was to be able to reclaim efficiently. I was also hoping to reduce the material cost of the casting slip. Currently standard ceramics cone 6 stoneware casting slip is reasonable and if it is purchased in quantity the price is hard to beat. As an example: On a gallon tote it's about The problem with Standards cone 6 is that you really have no idea whats in it and you have little control of it's characteristics.

Their cone 6 has worked well for me so far, but It could be a little better for the detailed molds I'm using. I also have used and like both types of their porcelain. The shrink rate is important to me, it's very close to other clays that I use. I'm surprised the shrink rate is not ball parked in many of the slip recipes that I have seen. Cone 6 Andrew Martin's white porcelain This would be about half the cost of the pre made porcelain. Some of the ingredients like frits are pricy. I'm sure other people cringe at the thought of buying a bunch of raw materials that may end up sitting on a shelf.

Are there some must have starting point ingredients? If you factor in your time, and the safety issues of working with that much dry material, it's well worth the price to just buy it.

In the big picture, clay is cheap, even when it's expensive. Standard is hard to beat for ready made material. After having a business with a larger profit margin I've been trying to make adjustments without cutting corners.

I have to keep every penny for pottery! It seems feasible to come in at half the cost with raw materials, but you would have to use a different materials. I'm not overly concerned about the mixing issues, I have a fresh air mask and out building that could be dedicated to Glazes and clay slip mixing, this should minimize exposure. The mixer should be able to run by itself until the slip is mixed.

I found a slip recipe that uses cheaper Nepheline Syenite instead of Feldspar. Oddly enough it has no ball clay. I'm not remotely sure what is a good or bad cone 6 slip recipe. I see that many of the recipes use the more expensive Grolleg over the domestic Florida, Tile 6, or Georgia Kaolin.

Is their any reason why you wouldn't use it, besides the slight color, Iron and Titanium content? I would also like to promote the idea that the clays are domestic instead of an import if it makes sense.I am going to jump off the deep end and cast some porcelain in molds that I have made myself. I am a thrower, so this will be new for me, although I have seen it done. Any help would be appreciated.

terracotta casting slip recipe

Hey TJR, I'm a thrower, too, so you'll probably get better info from people with more experience casting porcelain but I started casting the porcelains I throw with which is cone 6 Frost and cone 10 Southern Ice with a little paper in them. All I did was turn them into slip and add a little Darvon 7 to it. The white part with the colored circles in my oh I forgot what you call the little picture id thingy to the upper left of this post is cast and it is paper thin and very translucent.

So, if you throw porcelain you may want to consider using the same for casting. Thanks for getting back to me so fast! I forgot to say Cone I use a Plainsman clay called P I also use a stoneware from Laguna called Danish White.

I am assuming just a couple of drops of Darvan7? You can post now and register later. If you have an account, sign in now to post with your account. Paste as plain text instead. Only 75 emoji are allowed.

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Upload or insert images from URL. By using this site, you agree to our Terms of Use. Clay and Glaze Chemistry Search In. Reply to this topic Start new topic. Recommended Posts. Report post.

Posted December 31, Hey, gang; I am going to jump off the deep end and cast some porcelain in molds that I have made myself. Share this post Link to post Share on other sites. Mark C. These slip is from my collage days but I used to use it.

Porc slip- EPK I edited the sodium sill amount-check it out.Hi, I have recently been experimenting with converting a few of my production pieces to slip cast pieces. Since then I've made molds of my pieces and have cast several of them. Everything is going swimmingly except 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. It's working, but still gelling, I assume from the Iron in the clay. I don't mind if it is speckled or not, and it doesn't have to match red rock exactly, just be red. I don't have an answer to your question, but the fact that your clay is reacting differently than what you used at the workshop is not surprising.

The formula for casting slip will vary for each clay body, depending on its clay content, etc. I'm thinking this may be the way to go, It's probably the iron that is making it gel up so much, so if I add a mason stain, it may be the best way to go. I don't have a lot of experience making casting slips, but the only time I've tried to make a casting slip from a red clay it was an entirely painless and successful exercise. It was a UK terracotta clay, and the iron content wasn't an issue.

To be sure the supplier listed it as suitable for making casting slip, and supplied a body-specific recipe. Here are two ideas for you to consider I don't think my level of experience allows me to recommend any course of action. Look at powdered clays as well as moist ones. Regards, Peter FYI I pass on an Alfred guide on making casting slip in case it is of any help to you in judging the amount of deflocculant to use.

You will have to judge its utility yourself, I certainly haven't tried it. Hi Peter thanks for the info! My understanding speaking to Hiroe Hanazono is that in terra cottas the iron content doesn't affect the slip, but that in stoneware it can Go figure? Adding iron oxide to a clay causes it to gel badly on dispersion however the natural form of iron in Redart does not do this at all. So perhaps it depends on how the iron gets into the body, in a red clay or as iron oxide.

Have you tried adding more deflocculant to a small sample of your body? Does it thin it further? How does it modify the gelling issues? You can post now and register later. If you have an account, sign in now to post with your account. Paste as plain text instead. Only 75 emoji are allowed. Display as a link instead.

Clear editor. Upload or insert images from URL. By using this site, you agree to our Terms of Use. Clay and Glaze Chemistry Search In. Reply to this topic Start new topic. Recommended Posts.Ready-made casting slip is commercially available in all firing ranges, making it super convenient, but if you were wondering how to make casting slip from your regular clay bodythis post is for you!

If you like to combine handbuilt or thrown elements in your slipcast pieces, it can be very difficult to find a casting slip with exact same shrinkage and absorption characteristics as your regular throwing or handbuilding body, so learning how to make casting slip is a good idea for any potter or sculptor. A common studio challenge is trying to keep the number of different clay bodies you have on hand to a minimum. Throwing, handbuilding, casting, and surface design techniques often require different clay bodies to suit the demands of how your work is created.

Sometimes the clay bodies also need to be in different forms such as regular moist clay, slip or casting slip. So figuring out how to make casting slip from by regular clay body was a must. A singular work made of multiple clay bodies can cause several problems. Disparate shrinkage rates, maturation points, iron content, etc.

Making Pottery Clay : Clay for the Slip Casting Process

My sculptural work combines moist clay for general construction and casting slip for volumetric elements or for use with various image transfer techniques to address the surface. This assures that all the parts and surface treatments shrink the same, fire to the same cone, and all the glazes work the same on all the different parts. The great thing about this approach is its simplicity. All you need is a 5-gallon bucket, a drill with a paint mixer attachment, a deflocculantand the clay body you want to use as a casting slip.

If you work in a similar way, I highly recommend learning how to make casting slip from your clay body. The process of slaking clay to make it into slip is a simple one. Let it slake for 24 hours then mix it by hand a little with a stick figure 2. Keep mixing until the lumps are gone. At this point, I normally fill a quart container with the slip to use as a joining or brushing slip. The rest I use for casting slip.

terracotta casting slip recipe

To determine specific gravitywhich is a comparison of the weight of ml of water which is g and therefore has a specific gravity of 1 with the weight of ml of whatever liquid or slip you are working with. First tare zero out the weight of a graduated measuring container on a scale then fill it with ml of slip and see how much it weighs in grams. Once you know the weight, you divide it by the weight of an equivalent volume of water g.

This works out, in essence, to moving the decimal point in your weight measurement to the left by two places to get the specific gravity. In general, a specific gravity of 1. This number can vary, though, depending on exactly what is being cast. Different clay bodies have different optimal specific gravities that are determined by good old-fashioned trial and error.

Specific gravity is simply a tool for you to adjust your slip to meet the needs of your particular casting project. Once you find a number that works, write it down and stick with it for that clay body. If you have a specific gravity that is higher than 1. If the specific gravity is lower than 1. Once you have the correct specific gravity, you need to add a deflocculant to the slip to make it more fluid so it can be poured. Typically just a few small drops of liquid sodium silicate or Darvan is needed to achieve the appropriate fluidity.This week at the studio, Otto talked about having made slip to use in plaster molds.

So, I found a couple of articles to share that concentrate on these aspects and more. Slip casting is a good article covering the process from start to finish and includes formulas. Basically, the ingredients consist of clay in dry form, water, water glass sodium silicate. Cut the wet clay up into small pieces and let it dry out completely.

Put the dry pieces in a container and add water until it just covers the dry clay. Within a few hours it will be ready, next day is better, mix up and use. Here is another site that gives good basic information.

It is not an in-depth article, but covers the process of slip casting rather well. That sounds like an awfully long time. I like the idea of slip casting something, then altering it to make it more of my own. Since a piece is leather hard when unmolded, I would still have the time to make changes. Based on what this ceramist says, I would have to add a deflocculant like water glass or soda ash to make slip the right consistency.

According to the video, porcelain is a good choice. Tagged as Ceramicsclayclay slipdo-it-yourselfHow-toMoldpotteryslip castslip casting. Hi there Jan! I would like to thank you for your help in this article about Making Slip for Slipcasting. I am planning to start my own studio, but prior to it, I am looking for some information about how to reduce costs, like building my ceramic kiln and slip clay. As I live near banks of kaolin and quartz white sandI am searching ways to produce clay for slip casting locally, saving on money and transportation.

Do you know a good recipe in which we use them? Would you recommend any? Again, thanks for your help! Marcos, it sounds like you have great resources right at your doorstep. I will ask a few people who know more about this than I do and report back to you by comment here. Hi Jan, how are you doing?! Thanks for your reponse. It could only be better if an oil well poped up at my backyard.


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