Rim defect - slip casting

[Mitzuuu89 2]

Hi,

Anyone experienced similar defects when slip casting? Any solutions? Create a extra paster ring and cut after?

Thanks!

 

[Mark C. 3,716]

your photo does not show any defects??

[Mitzuuu89 2]

3 hours ago, Mark C. said:

your photo does not show any defects??

There’s a ridge formed at the rim

[liambesaw 1,566]

Looks like a feature to me! Nice and smooth on the lips, a little extra clay there for some strength.

But yeah, could probably cut it off if you don't like it.

[Mark C. 3,716]

Is the lip the top of mold and you cut it off in mold ?or can you tell us more about the mold details?

uneveness is where layers of slip build up as slip dries and level drops in molds

usually one has so room in spout for this to happen and be cut off-

[Mitzuuu89 2]

9 minutes ago, Mark C. said:

Is the lip the top of mold and you cut it off in mold ?or can you tell us more about the mold details?

uneveness is where layers of slip build up as slip dries and level drops in molds

usually one has so room in spout for this to happen and be cut off-

My mold is exactly the size of the object, so no extra room to cut it off

hm ok.. i’ve tried to be careful to make sure the mold is always topped with slip, but the top layer dries as well, so that might be the reason as you mentioned.

 

[Mark C. 3,716]

Molds will suck up slip as they dry and if yours in the exact size there is NO room for this to happen-Thats whats going on.Molds need a spout or a space for slip level to drop and then you add more slip as the time goes by as the walls thicken. You must includ this space in your mold.

Hopefully you understand what I'm saying.

Your uneven rim is becuase slip is drying and the level drops you add some but its already dried so thats your issue .

 

[Mitzuuu89 2]

9 hours ago, Mark C. said:

Molds will suck up slip as they dry and if yours in the exact size there is NO room for this to happen-Thats whats going on.Molds need a spout or a space for slip level to drop and then you add more slip as the time goes by as the walls thicken. You must includ this space in your mold.

Hopefully you understand what I'm saying.

Your uneven rim is becuase slip is drying and the level drops you add some but its already dried so thats your issue .

 

thanks for addresing my issue! i'll try to include some space in my next molds, and see what happens

[Chilly 701]

On 7/3/2019 at 8:34 AM, Mitzuuu89 said:

thanks for addresing my issue! i'll try to include some space in my next molds, and see what happens

You need a funnel built in to your mould, also called a sprue.  It is shaped so you can run a flat plastic blade around it, to remove the excess thick/thin build up.  I'll go take a photo later so you can see what I mean.

[Mitzuuu89 2]

53 minutes ago, Chilly said:

You need a funnel built in to your mould, also called a sprue.  It is shaped so you can run a flat plastic blade around it, to remove the excess thick/thin build up.  I'll go take a photo later so you can see what I mean.

great! thanks

[Chilly 701]

Let me know if there's anything you don't understand.

The tool is called a Lucy Tool.  The fat end is good for prising moulds apart, the thin end for removing the sprue waste.