A Slip Caster Talks Shop | Alison Thyra Grubb | Episode 761


Alison Thyra Grubb | Episode 761

Alison Thyra Grubb makes iridescent ceramic jewelry and homeware in her studio in Aberdeenshire, Scotland. Alison graduated from Gray’s School of Art in 2019 where she studied 3D design, specializing in ceramics. Alison’s geometric ceramics are made using a combination of slip casting and 3D printing and are decorated using colour changing lustre glazes.


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Why so much emphasis on slip casting?

I think it’s because I really like making the geometric shapes and slip casting was the perfect tool to do that. It was the perfect process to make the style that I wanted to make. And also because what’s really nice about slip casting is that (as I was talking about the 3d printing)  it leaves these lines in the texture, the way the print is built up in layers, like lines. And sometimes I like to emphasis these lines because it’s a really nice surface pattern. So the slip casting is perfect because the plaster is so good at retaining al these tiny little textures. So it’s just perfect for that.

Is a 3D printer essentially the same thing as a silicon mold because it’s saved on a digital file as opposed to a physical file?

As in I will always have the master piece?

Yes, the program or the plastic piece. 

Yes, basically it’s exactly that. Even if the 3D prints themselves, I do work on them. I sand them so they look how I want them to look but I have used them multiple times to make plaster molds. I have the used the same 3D print to make several plaster molds and if I look after it and don’t damage it, it will last for a very long time. So even if I was to destroy that plater mold now, in a few years time I would hopefully be able to remake it with the 3D print.

When you use plaster, is it a specific kind of plaster or can you just get any old plaster from the hardware store?

I think it has to be the fine casting plaster because it’s not got any coarseness in it. I don’t know what the builder’s plaster would be like. I’d imagine it’s a bit coarser. I think it’s slightly a different color as well because fine casting plaster is pure white. So yeah, fine casting plaster is what I use and it just brings up beautiful details with the 3D prints.

Is the slip  just clay and water or are there other additives in it?

I don’t make my own slip myself. I actually by it from a manufacturer but it does have deflocculant in it. I think it is soda ash and sodium silicate. When I get the actual buckets of my slip I do have to put them into a larger vessel and add water to them. I think when they sit in the buckets the water evaporates. It’s just like sludge, so I work on it so it’s the consistency that I like.

To get the right consistency do you use a hydrometer or the finger slip test?

Yes, it’s the finger slip test. I don’t have a hydrometer. I have never used that before so I suppose it’s bit wishy washy. It’s by eye and by feel but I have gotten better with time, I think. I like to do a test cast just to make sure I have got it right and it is not going to be too thin or too thick and if it is I will just do an adjustment.

How long do you typically leave the slip in the mold before you empty it out?

It is different for every piece I make. When I do the first cast of a new piece I like to figure out exactly how thick I want it to be because I want it to be nice and delicate but I don’t want it to be too delicate. I just don’t like them being really thick but I do like my mugs to be a little bit thicker than the rest of the other pieces that I make. I want it to be nice and strong because you are using so often.

When a piece doesn’t work can you recycle it or is it a loss?

No, we recycle it all. All the scraps I trim off or pieces that fail, I let them dry out completely in a bucket under the table and I add the water back to it and mix it up. I usually have to add the deflocculant again. But yeah I recycle it all.

How many different glazes did you go through to finally decide that is your final product that you wanted to get to?

I actually use two different types of luster glazes. When I decided I wanted to make the lusters, as I said at the start, I like shiny things, I wanted to make shiny things. I love glaze making so I tried lots of different glazes that I thought their colors were pretty when I was in art school and I like glaze making and then I went to open studios a few years ago in my area and there was this potter who made luster glazes. Her name is Fiona Ducket and she makes in glaze lusters, so you make the glaze like a normal glaze and fire it in an electric kiln. It look pretty boring, like green or clear or whatever, and then you put it in a gas kiln, this the fun part, you reduce it and through the reduction the oxides come out in crazy , iridescent metallic colors. It’s so cool.


Big Magic by Elizabeth Gilbert 



Instagram: @alisonthyraceramics

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