Slipcasting Marbling Effects Help

[Fusionous]

Hello everyone! A question & issue: made my own plaster mold and tried marble slipcasting, but, when i tried the marbling technique, the marbling seems to disappear after i poured white slip in. I tried to trim the slipcast pot but the marbling is gone... did the colored slip blend into the white slip? What i am trying to achieve here is to have the base white, mid section to have the marbling and then the top to be white.

What i did:

1. Poured white slip at base, create a layer of white base, pour out white slip

2. poured in colored slip (pink and red)

3. swirled the plaster mold to ensure the slip registers on the inner plaster wall

4. poured remaining white slip into the mold to the brim to let it thicken

5. take out dried slipcast pot to trim, marbling disappeared/non-existent color .

I have another tried other method:

1. Pour white slip till 1/4 of base as i only want the marbling effect to show at mid body, base remains white

2. with the 1/4 pool of white slip, i poured in colored slip (red,pink) and swirled abit to ensure it registers on the walls

3. fill up the plaster mold with white slip as i want the rest of the slipcast pot to be white

4. wait till pot thickens and pour our the remaining slip

5. trimmed pot, still no marbling except dabs of colors here and there...

 

Any advice is greatly appreciated

[Chilly]

You might need to scrape a thin (very thin) layer of white to reveal the red and pink.

How different are the three colours when dry?  Sometimes they show better when bisqued.

[Fusionous]

Just now, Chilly said:

You might need to scrape a thin (very thin) layer of white to reveal the red and pink.

How different are the three colours when dry?  Sometimes they show better when bisqued.

on the 2nd picture i think, theres a small little red dot which is the red slip and the pale pink which is the pink slip and the slip is greyish when wet and becomes white when bone dry

[Rae Reich]

Because you are pouring your slip in and out, you are either coating the area before it can be marbled (first try) or mixing the two colors in the mold before pouring out (second try, except for the spots where the second color hit the side of the mold before it all became mixed).

Since the original marbling that you want to approximate was done by layering or kneading different colors together minimally before shaping by throwing or rolling out or carving, you are not likely to get the same effect by pouring together two liquids of the same viscosity - they will blend naturally. 

You could open your mold and paint the first color on the surfaces in a pattern you want, then close the mold and pour the second color. The marbling will not, of course, go all the way through, so carving the surface will not reveal more. 

You could use block clay instead of slip, stacking your colors and rolling out 1/4" - 3/8" slab that you press into each side of the mold, then joining the halves together when they are firm enough to remove. In this case, the pattern won't match at those seams.

I have a commercially made straight-sided slipcast mug with a marbled pattern (made in China), but a close look at the footring reveals only white clay, the marbled pattern ending with the glaze, so I think the glazing was done with the pouring technique used in acrylic marbling pours (see YouTube). If you tried that technique with pouring slips into a mold you would need a second hole in the bottom of the mold for the marbled slips to continue pouring out without disturbing the pattern. Then you could plug the hole.

 

[oldlady]

just an idea i was not allowed to try in a classroom.  using a small container,  put one color slip into the mold and tip, swirl, move that colored slip all around inside a dry plaster mold.  (should not be enough to pour excess out.)   after it is dry, add a second color in the same way, moving the new colored slip in a different direction.   let it dry.     then slowly pour in white for the background.  pour out excess when it is thick enough.  

might work.

[Fusionous]

1 hour ago, Rae Reich said:

Because you are pouring your slip in and out, you are either coating the area before it can be marbled (first try) or mixing the two colors in the mold before pouring out (second try, except for the spots where the second color hit the side of the mold before it all became mixed).

Since the original marbling that you want to approximate was done by layering or kneading different colors together minimally before shaping by throwing or rolling out or carving, you are not likely to get the same effect by pouring together two liquids of the same viscosity - they will blend naturally. 

You could open your mold and paint the first color on the surfaces in a pattern you want, then close the mold and pour the second color. The marbling will not, of course, go all the way through, so carving the surface will not reveal more. 

You could use block clay instead of slip, stacking your colors and rolling out 1/4" - 3/8" slab that you press into each side of the mold, then joining the halves together when they are firm enough to remove. In this case, the pattern won't match at those seams.

I have a commercially made straight-sided slipcast mug with a marbled pattern (made in China), but a close look at the footring reveals only white clay, the marbled pattern ending with the glaze, so I think the glazing was done with the pouring technique used in acrylic marbling pours (see YouTube). If you tried that technique with pouring slips into a mold you would need a second hole in the bottom of the mold for the marbled slips to continue pouring out without disturbing the pattern. Then you could plug the hole.

 

I am using a 1-piece mold, painting is abit difficult to do. So if i understand correctly, it is to make the marble first and then pour onto the greenware?

2 minutes ago, oldlady said:

just an idea i was not allowed to try in a classroom.  using a small container,  put one color slip into the mold and tip, swirl, move that colored slip all around inside a dry plaster mold.  (should not be enough to pour excess out.)   after it is dry, add a second color in the same way, moving the new colored slip in a different direction.   let it dry.     then slowly pour in white for the background.  pour out excess when it is thick enough.  

might work.

If i let it dry, it will cause crack, as if theres 2 layers of clay

[oldlady]

so you have tried the method i suggested?   i thought it would work since the dry stuff is stuck to the plaster and when the white slip is added, it would just soften the colored stuff enough to surround the color and both would become the same degree of wetness.   once you pour out the excess, the colors should stay stuck to the plaster and the white will stick to the parts that are not covered with color.

[Fusionous]

Just now, oldlady said:

so you have tried the method i suggested?   i thought it would work since the dry stuff is stuck to the plaster and when the white slip is added, it would just soften the colored stuff enough to surround the color and both would become the same degree of wetness.   once you pour out the excess, the colors should stay stuck to the plaster and the white will stick to the parts that are not covered with color.

yep, letting it dry on the plaster wall creates a "piece" which somehow wont blend with the 2nd layer of slip i pour in. This creates like a line between the 2 layers

[Rae Reich]

If I understand @oldlady, she meant to pour the full coat before the marbling dries up. Work quickly.

[jrgpots]

My daughter does poured acrylics by slowly pouring the different paint colors in a cup, then without mixing them, pours them on the canvis.  There are lots of youtube videos of the technique.   What if you adapt this to you slip pouring?   Here is my idea.

1. Find the total volume needed  for your pour.

2.  Usee 1/3 that volume as  color #1,  1/3  as color #2, and 1/3 color #3.

3. Carefully, add the 3 color slips into a large  container, then pour this into the mold.

4.  Wait until you get the desired thickness and then pour the slip into a second mold. 

5. Don't swirl the slip inside the mold.  Just tap it to remove the bubbles.

Each time you pour, the colors will get more mixed or muttled.  There would be a limit to how many times this could be done until the slip colors would be too mixed.   At that point, you would have a new slip color. 

 

Jed

[mnnaj]

Doing like OldLady suggests will create a line,  but if you work quickly it the white will absorb around the color - the color won't pop off.

Another idea might be to coat the entire inside of the mold with a thin coat of the color(s),  add  the white for thickness.  Then when the piece is bone dry use a resist and do some hydro-abrasion to wash the color down to the white.  It might not look like marbling, but it can be cool.