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veronica

trying to scale up, what building technique is best?

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Dear ceramic arts daily community, 

I am a design student  and I am trying to scale up a model I made of a terracotta clay drinking fountain I designed, my knowledge of clay is proving limited as at the moment as I am finding difficult to make this fountain in a real size (90 cm height) I will coil for the stand , I made a press mold for the basin yet not sure whats best to approach the curvy joints. please find a picture of the small model I made. any suggestions for building?  how can I  translate this design to a bigger scale?  any thoughts? 

Best Wishes

Veronica

image1.jpeg

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Coiling will work OK,

but some of the more important questions are:

What are the structural loads on the item after it is scaled up to its final size?  Are all the dimensions scaled at the same ratios?  What are the minimum wall thicknesses necessary for the fountain to stand alone and function properly?  These answers will useful in the choices of forming. 

How heavy will the fountain be as it is being made, at the bone dry stage, and at the final conditions?  The answers here influence the decisions on making the object as a single piece or making it in parts to be assembled at a later state. 
How will the fountain be fired? [Related to the available kiln configurations available to you].

Does the fountain need to be fired to the clay body maturity temperature (aka zero water absorption) or can it be fired to a lower temperature? This decision will influence choices of clay bodies and firing requirements. 

What is your time allotment to work on the fountain?  When is it due, and how many hours per day will be available to work on the fountain?  

How will you dry the fountain? 

How will you handle the fountain while it is being constructed?  Total weight will have a large influence on what you must do. 


How will the fountain surface be decorated? Is glazing required? 

If I were designing this fountain to be an commercial item it most likely would be slip cast like a toilet or sink.  As a single item it would be constructed in sections of coils and slabs. I would not start work until all the other questions have been answered with reasonable estimates where needed. 

LT
 

Edited by Magnolia Mud Research

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Dear Magnolia Mud Research,

Thank you very much for this useful feedback,   it is a one-off item and  I am not very sure how will weight when dry, yet walls are being calculated to be  2.5-3 cm thick to make it quite sturdy . I built jigs and boxy-templates in parts to hold the shape of the fountain while wet, yet it is probing challenging and getting wobbly after 40 cm height , as I dont leave it dry completely cling filming it. What would be the best approach to this?  

At the moment I am having a Sunday break from clay and  I escalated this model on cardboard and on its way I modified some measurements, for example the basin will be approximately a 20% smaller so not too heavy on that "arm" so it doesn't hold as this is my main fear. The stand will be straighter as it is better for wheelchair accessibility. The measurements have to make them accessible for children, hence the 90 cm height and to be installed in a community garden.

I don't intend to glaze it, I would prefer a slip on the same color, terracotta, as I like its natural appearance. The fountain doesn't need to be watertight, so probably fired at a lower temp and  it will be connected to a mains through a copper pipe and spout continuing 15 cm the clay spout added on the top surface after the firing( I will create a cavity on the clay that will allow the pipe to sit in it, aware of the 12% shrinkage and all). The fountain will have to be dried naturally as we don't have any other way at college, it would be ideal to accelerate this process if possible as my deadline is approaching  (31st may), but how?. I am available to work 5-6 days a week til the deadline.

Any thoughts? 

 

Best Wishes

Veronica

 

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The conventional way to build large is to use an armature to support the form while building up.  When your form is sculpted and has started to firm up, cut the sculpture in half (or thirds or whatever it takes) so that you can remove the armature.  Hollow out the inside to your 2-2.5 cm thickness and then score, slip, and reassemble.  Take care to blend any seams or distortions you’ve created.

That’s how I would approach the project.

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based on your comments this is how I would build (with anticipation of having to observe, adapt, improvise, and overcome as I go) the fountain:

use a coarse clay body that dries fast. 

start at the bottom with large coil as a base to build on.

add several coils around the base and then using a paddle and anvil technique compress the clay into a uniform wall for the column. 

build up the column and shape the exterior as you go.   If the column starts to show signs of buckling, stop building upwards.   Put plastic on the top 2-6 inches of the column and let the remainder dry for several hours.  When dried enough to hold up the next two coils worth of column, add the coils with all the scoring, slipping, etc., and then use the paddle and anvil steps to compress and shape the fresh clay segment to the desired form.   Pay close attention to the moisture content as you go using a water spray to keep the working areas moist. 

Repeat the these steps until the fountain is finished.   At the basin area, you probably will need to have an exterior scaffold to support the basin while being formed and drying.  

As the fountain grows in height, the wall thickness can be reduced.   When changing the wall thickness make the transitions smooth and gentle.   Abrupt thickness changes are regions where cracking (dunting) can start. 

The model fountain implies that the basin holds a significant amount of water.   Make sure that the structure is such that it will be stable adequately supported.   The transition from the column to the basin probably should be less abrupt, that is it should start its slope towards the column further out from the column that in the model.   This is a mechanical structural issue.   The basin produces a load from its own weight plus the weight of the water it will hold when full. 

You also need to locate the center of gravity of the fountain when it is in its operational state including the water contained in the basin.   You do not want the fountain to be unstable when in use. 

My guess is that you will use at least two boxes of clay.   Can you handle a 100 pound sculpture and get it safely from your construction site to the bisque kiln without having "Scotty  beaming" it from here to there? 

If you have to make the fountain in several pieces, consider having each piece fired separately and assembled afterwards.  

You indicated that you want the decoration to be unglazed stains.  These can be added at the bone dry stage and the fountain could be single fired. 

This is a doable and an ambitious project.  

 

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Dear Magnolia Mud Research, 

Thank You so much for all these details, I am taking notes for tomorrow, I am starting to build it with all this feedback bearing in mind, I will place it in a wood board on castors so I don't need to "Scotty beam it" much. 

I am coming to realize that as you noticed this is an ambitious project, it is my final year piece, I'm glad to read that it is doable though! I will try my very best, thanks one more time for your invaluable experienced advice and time!

Best Wishes

Veronica

 

 

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You are really pushing it to get this project finished in two weeks.  You may need to set up a small fan to help dry it ,  you will need to keep moving it around it to get it to dry evenly.   If you can blow some air on the inside that would also help speed up your drying.   You better check on the firing schedules and the ability to get that large of work into a firing.  I made a piece that large when I was in college and it took a couple of months before they found a place for it in a firing.  You could probably get it into a bisque firing and be able to present it that way at your critique.    Potter

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Thank you Denise I will definitely use a fan to speed up the drying,  and inside too. Yes , that will be possibly the way I will present it as the ceramic workshop  is very busy.  Another  possiblility is firing it in pieces and assemble it once fired . 

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Recently I discovered that the "Crystals" type fancy cat litter sold in grocery stores now is basically the same desiccant they put into those little packets you sometimes get with things you buy that need to stay dry; like medications and such. If you get into a bind with your drying times you might make up a couple paper bags/coffee filter packets of the stuff, -I've yet to try this so be on your guard in case it dries too fast and cracks- and place them on the inside to aid with drying. 

This is an untried experiment to me, heard about it in a Youtube gardening video about storing heirloom seeds. I wish I could give you more advice but the cat litter is about $10 or more for a bag and I haven't had the need to give it a decent try in this regard yet. 

Best of luck, I hope your teacher appreciates your effort! 

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