Kupu Keramik

Welcome bin wilujeng sumping di blog Kupu Keramik with Natas Setiabudhi
. Blog ini berisi curhat ataupun sharing teknis tentang keramik art dan craft
juga hal-hal lain berkaitan dengan keseharian penulis. Bila ada uneg2 mangga pamiarsa komentaran secara blak-blakan..any comment I will accept openly..


Natas Setiabudhi

Wednesday, August 7, 2013

Reproduction the mold

2. Masking with separator
1. Let one part released (two parts left)

3. Round parts left by barrier
4. Ready to pour plaster slip

5. One part complete (new one)
6. Open 2nd part (old one) ready for new one 

7. Three parts completely

To reproduce the molds is more easier than make it from beginning. Firstly join each part of mold, but let one part released (fig.1). If there is no sphere on the model, you can add clay on the top (fig.2). After pour for one part go for second part and so on until third part.

Every finished with each part mold, you must wash the surfaces by wet sponge and clean the remains or remove something untidy. After all parts mold completely use sand paper to make smoother and wash again until have clean surfaces (to remove separator). If there is still remains left e.g. separator, it will be stick between clay body and the mold. Or if inner shape of mold has potentially stuck, the ware will be deformed or damage when opened, so you must remove some parts neatly.    

Tuesday, July 16, 2013

Make a Model: Clay to Plaster

There is one of way for making plaster model from clay model. Sometimes we will have difficulties technically to modelling the plaster model. We can not easily cutting or adding for the shape if compared with clay.

In this way you firstly must making the model from clay. The plaster cover don't too thick approximately 2 cm. To add the plaster slip to clay model like a sculptor way little by little. Next step you mark the plaster surface by knife and saw it until 2 millimeter depth not through. If cut through there is no bonding if paired back.  

When you will release plaster model from the mold, it doesn't matter the mold become broken or damage. You first must save the model. To make easier you must divide each part of model correctly, furthermore for making casting mold. Wrong in dividing, definitely will have difficulties in releasing model from the mold (model stuck in mold). In this situation potentially what you have done will be unsuccessful. Sometimes you must start from beginning again. 

1. Ready to pour plaster
2. Cut by knife just for mark, not through

3. Use saw but not through
4. Use hammer to hit knife grib to make 2 pieces 

5. Two pieces
6. If paired back will have exactly joined
8. Pour the plaster slip
7. Masking with separator

9. After opened and have sand paper
10. The results

Thursday, May 9, 2013

Make Casting Mold from Plaster Model (One Piece)

The main principle for making one piece mold is the shape must wider to the top, for instance a bowl shape. Minimal has straight line from bottom to top, like cylinder cup. If has curve line in some area, even slightly the model can not release from the mold. It will be stuck. 

Another thing must be note is a kind of separator we used. I make separator by myself from white bath soap. The soap is cut into small pieces and cook with little water and coconut oil. The result is liquid mixture. This separator is good enough to me. To apply the separator on the model surface can use sponge like picture in the bottom. The process binding needs several times until has shiny surface.

To release model from the mold, you back mold and struck by hammer. But do not directly must be put the wood first (fig. 5). To hit the mold you must use shock technique, do not use full power. Before that you need put the props, so after hit several times the mold will go down by itself (fig. 6). 

1. Place the model on bat and a gap between model and bat cover with wet clay

2. The excess of clay trimmed neatly

3. Use separator

4. Pour plaster slip

5. To release the model struck the bottom by hammer (use props)

6. The model will release after struck several times

Wednesday, May 8, 2013

Trimming Plaster for Model

1. Make a base clay for model
2. Using fiber make a boundaries and tied
3. Pour plaster slip
4. Ready for trimmming (cheese hard)
5. Trimming
6. Completly model

Usually model for casting is made of clay. The forming technique could be throwing, pinching, or coiling. As alternative, you can use ready made product like artificial bird, mug, or plastic glass. For long usage you can use plaster, meanwhile the clay model will damage for once used. Also the plaster model is useful in consistency of size if make for next molds. 

The standard procedure making model is using special equipment. But actually you can use kick wheel. The important is a right moment for trimming and kind of tools. The tools also do not need special ones, we can use simple tools like iron cutter, iron scraper or iron ruler. Trimming for plaster and clay is really different. You need more effort to trim plaster.   

To shape the plaster model you must have some tricks for satisfied result. The plaster don't let hard, but must in cheese hard to begin trimming. It must be in hurry because the plaster will be hard by time to time so that it will be more difficult for trimming.

Monday, January 28, 2013

Make a Bowl by Solid Casting

There is another technique in casting besides drain casting, it's called solid casting. As general drain casting is pouring the slip into the mold and when have certain thickness the remains poured  into container back. While solid casting there is no remains, the slip is allowed to semi leather hard in the mold. Actually there is still remains to poured back, but very little just for making a foot rim (fig.4). Another characteristic is the drain casting for getting outer shape, meanwhile solid casting for getting outer and inner shape. Therefore the mold of solid casting could have a positive and negative shape.

Technically solid casting is more difficult. The bowl often stick to the mold. Usually before pour the slip, each mold is given talc powder evenly. Also the slip consistency must fluid enough. When the bowl start to separate to the mold, you can hit by hand the edge of mold for several times, until make a gap between bowl and mold.

The  results of solid casting are more constant (shape and thickness), because drying process more even (have two shape molds: positive and negative). But anyway, there is form limitation for the technique. The form must be simple and wider into the top, such as bowl or cone. The form like vases wide then tapers back can't be done by this technique, because it will be stuck when lifted from the mold. 

1. Pour the slip
2. Wait until the certain thickness

3. Pour the slip back
4. Keep the mold in first position

5. Lift the positive mold

6. Keep the bowl in negative mold

7. Wait until the bowl separate