Tag Archives: bust

A Ceramic Portrait Bust

A completed ceramic bust of a handsome African man

Portrait bust by Lucy Mellersh

A ceramic portrait bust needs to be hollow in order to be fired in a kiln, it can be made in two different ways: either as a solid mass which is later hollowed, or it can be built directly as a hollow form.

The method I’ll show you here is building up the bust as a hollow form. It’s a good choice if you know from the outset that you’ll be firing it, rather than using it as a basis for a cast, for example in Bronze.

Hollow building has the advantage that you avoid potential damage during the hollowing process. However, because of it being hollow, you need to work in a different way than you may be used to. Creating the sculpture from the bottom up. You are able to adjust it later, but it’s good to be as accurate as possible as you go along.

Start with good water-based clay that has a high grog content, the grog makes it more stable and reduces shrinkage.

The H-shaped base of a clay bust

 

Use a wire to cut thick strips of it straight from the bag and form an H shape as shown here. The front and back are the chest and shoulder blades of the bust. Think of the middle line as a kind of backbone for your bust, it will stabilise the structure right up into the head.

Keep building up, layer after layer, making sure to join the strips by squishing them hard and avoid trapping air.

A column of clay as a temporary pillar inside the arch of the shoulder.

When you reach the top of the shoulders and want to join front and back, you may have trouble keeping the stability for the arch of the shoulder, it helps to build a temporary pillar to support the damp clay of the shoulder.

 

 

Partially made sculpture showing shoulders and necking the

Build up the shoulders and neck, keeping a careful eye on your subject to capture the individual details of the muscles and bones in the neck which can be particularly beautiful in young people. This is also a good time to add clothing details or jewelry.

 

Continue building up the neck and chin, keeping the centre partition.

process4

process3At this point, I find it helpful to create an accurately proportioned profile on the middle partition to use as a guide.

Check to make sure the neck and shoulders match up properly to the profile of the head.

 

 

 

partially made bust showing centre partition with pinpricks

 

Slowly work outwards from the profile line to create the chin and mouth area, then gradully work on the width of the nose.

I like to pinprick the centre partition as I go along, this allows any air bubbles to escape during firing.

 

 

Partially finished bust showing a man's brow, nose, mouth andchin.

 

Once this is all in place, focus on getting a likeness in the nose and mouth area.

 

Keep the model damp by spraying frequently with water and by wrapping the bits you’re not working on in plastic bags.

 

 

process7

 

I complete the cheeks and back and sides of the head before I start working on the eyes.

 

 

 

 

 

 

process_headrest

 

As the lower parts of the sculpture harden, they can usually take the additional weight as I build up the bust.

However, the face may get rather heavy for the neck of the sculpture to hold up, so I like to rest the chin on a support as I work.

 

process_almost

 

Once I’m happy with the face, I finish building up the back, sides and top of the head and then close the sculpture at the crown.

 

 

 

pinprick

 

When the head is complete, and before I work on surface textures or details, I pinprick through to the inner cavity on the entire sculpture. The pin-pricking ensures that any air bubbles I may have trapped can escape during firing.

 

I smooth the surface, create the texture details and let the whole thing dry very slowly before firing.

Advertisements

Casting a bust in a two-part mold

WP_20150503_15_59_44_ProOK so now I have the mold ready it’s time to cast a bust in plaster of Paris.

When I first made a cast I was surprised at how time-consuming the whole process was. I’d imagined just sloshing in the wet plaster, letting it set, taking the hardened model out of the mold and then just pouring another one. Although those are the main steps, and that works fine for casting ornaments or rough objects, it turned out that the precision needed for an artwork translated into a very slow and fiddly process with days of repair work at the end shaving off imperfections and filling holes left by tiny air bubbles.

I realised that casting a life-sized bust in a two-part mold would be trickier than just an open-backed relief. I couldn’t find instructions for this on the Internet.

  • Do I put the halves of the mold together and fill it up from underneath?
  • Or do I cast two halves and then stick them together?

Well, I ended up needing to use both methods to get a finished product and this is what I’ve described below.

Continue reading

Casting portrait busts – Making a two-part mold

finished portrait busts in damp clay

finished portrait busts in damp clay

The double portrait busts are finished in clay and instead of firing them in the kiln, I’d like to cast them.

They are not dried out, but still softish damp clay. Damp clay won’t stick to plaster or silicone.

When I was satisfied with the bust modeled in clay, I started to make a mold, this is a bit like a jelly mold and will allow me to make more than one reproduction of the busts.

The fine detail of the portrait will be copied using a flexible silicone mold. Silicone is a sort of soft synthetic rubber. This forms a thin layer that can curve under slightly, going into the hair, ears, eyes and nostrils. When the silicone layer is removed it stretches so it can be taken off without damaging the cast.

To hold this floppy silicone layer in place there is a jacket of hard plaster, often called a mother mold. The plaster mother mold has spaces that fit special bumps on the silicone, these are called register keys and ensure that the silicone layer is positioned correctly inside the mother mold.

I’ve used this same process when making a relief of a bull inspired by a Picasso lithograph.

Toro relief in plaster

Toro relief in plaster

For a bust, the mold is made in two halves, producing a front and back, each with a flexible silicon layer and a rigid plaster outer layer, these two halves will fit together.

Day 1

  1. The first step is to position the bust, face up, on a steady table, making sure the back of the head and neck are properly supported.
  2. Then you need to build up a clay edge all around the bust, build this up in clay of a different colour so you can tell the difference and don’t accidentally start scraping at your original bust (I used grey clay for the edge on a dark brown bust). Another tip is to lay the bust on cling film so that a thin layer of cling film (saran wrap) is between the two clay colours, let a half centimeter of this lay on top of the clay edge.
  3. Choose a line, going from the arm, up the outside of the shoulder, up the neck and over the head to the other side. It’s best to choose a route that doesn’t have too much detail, the line doesn’t have to be totally straight. This line will be where the two halves meet. The clay edge needs to be quite wide because it’ll have various register keys and the sides of the plaster mother mold on it. Make the edge very very smooth on top and bring the edge of it right up to the bust.
  4. Once it’s ready, scoop some rounded register keys into it. Some people make a smooth furrow all the way around the edge, I just scooped several 4cm long spaces out. These will let the two silicone halves of the mold position exactly with each other and with their respective mother molds.
  5. Now make up some thin silicone and dribble it in a fine stream over the face, neck and chest. It will continue to flow for quite a while and end up pooling on the edge and in the register key spaces. The silicone may also dribble onto your table or floor, don’t try to wipe it while it’s liquid, just wait until it has set and then peel it off.
  6. Get a block of clay, flatten the top and create about 20 conical spaces in the clay, fill these with some of the silicone and leave them to set overnight. These will be little conical register keys made of silicone, they will position the silicone mold inside the plaster mother mold.
Bust with silicone layer

Here you can see the grey clay edge, the brown clay of the original bust and a thin layer of silicone over all of it, pooling in the register keys (indentations in the grey clay edge).

Day 2

The next day you can trowel over a good layer of thickened silicone making sure to fill in any overhangs so that the rigid plaster mother mold can slide on smoothly without catching.

Position the conical register keys into the silicone around the outside of the bust (and on it too) and let it set.

The wet silicone is very sticky but can be patted smooth with a sponge covered in cloth that has been dipped into a strong solution of washing up liquid and water. Make the silicone layer as smooth as possible.

Day 3

First cut some register keys into the outer edge of the clay edging. These will be to position the two plaster mother molds onto each other. Use a sharp knife to slice through the silicone and down about a centimeter into the clay. Make these register keys very smooth with bevelled edges.

Register keys

Here you can see two types of register keys: At the top are two dips for aligning the silicon back and front layers to each other and at the bottom of the picture is the cut-away for positioning the mother mold halves on each other.

Now make up some plaster and smooth it over the top of the silicone layer. The layer of plaster should be 2-3 cm thick and should have some hessian strengthening in it. Make it nice and thick at the edges and be sure to fill those freshly cut register keys.

Make sure the plaster is nice and smooth on the outside otherwise you’ll scratch yourself when handling the mold once it’s dry.

As always with plaster, have a bowl of water for hand and tool washing, dump this on the garden when you’re finished, never into the sink or toilet.

Voila, one side done!

Day 4

Turn the whole thing over to expose the back of the head. Peel off the clay edging. Wipe everything clean of the clay. 

Smear a thin even layer of vaseline over the exposed silicone surface and the exposed plaster in the plaster register keys which are now protruding. The silicone mustn’t stick to the next layer of silicone, the plaster mustn’t stick to the next layer of plaster.

Now go back to step 5 on day one and repeat the entire process.

Back of the silicone mold before making the plaster mother mold

The back half of the mold is ready for its plaster jacket, the mother mold. Note the different types of register keys.

Here you see the back half once it’s ready for the mother mold. The silicone is cleared from the plaster register keys at the edges, the conical silicone register keys are set into the silicone around the mold to position it into the mother mold and the long humps are along the divide to match the two silicone halves together, the surface of the thickened silicone has been patted down.

Once the back of the mold, including the mother mold is set, it’s time to scrape away at the sides until you can see the divide all the way around, now gently but firmly prise the halves of the plaster mother mold apart. You’ll have a mother mold on one side and all the rest on the other. Slide your fingers between the two silicone layers all the way around the edge then gently peel back the silicone.

The clay bust can be discarded, the mold is ready for casting.

WP_20150503_15_59_44_Pro