Took Back Side Of Platter Mold And There Were A Much Of Hairline Cracks/lines

[Hollyfaucheux]

I just took the back side off a Christmas platter I am making and there are a good bit of like hairline cracks but not really cracks it's just like lines... Went over it once with a paint brush and they are gone... The back of the mold has not cracks/lines anything that would do that... It's perfectly flat... Any idea why that has happened???

[oldlady]

did the slip get poured all at once or was there a series of pours to fill the mold.  assuming that you are referring to a poured slip piece.  the additional pours would cause a slight difference that you might think of as cracks.  as the slip dries during the short time waiting for additional slip, there is a skin formed that is then altered by the additional slip. no weakness or problem should result.

[Hollyfaucheux]

Nope, it was all one solid pour.. Could it have been that the slip was not mixed well enough?? My mixer is broken so I have been doing it by hand and I have been worried about not mixing it good enough.. But it is also premixed Machies Slip.

[No Longer Member]

Nope, it was all one solid pour.. Could it have been that the slip was not mixed well enough?? My mixer is broken so I have been doing it by hand and I have been worried about not mixing it good enough.. But it is also premixed Machies Slip.

 

 

Yes, that is possible as well as maybe not enough water in it. The thing about pouring platters is that you really can't get 360 degree continual feed of slip through the pouring spout, thus one side will get more slip than the other. Sometimes you'll move when pouring and that causes the slip to go into the mold in a different place. If the slip is too dry and the mold has dried pretty well since the last pour, the slip may dry too quickly to blend seemlessly with the other slip once flow heads back in that direction.

 

 

Are you using a pouring table or just going straight from the bag? Mix your slip well if in a machine and/or knead new bags of slip well before adding to machine or pouring. The wetter slip is the easier it is to pour seemlessly on big pieces BUT it takes both the piece and mold longer to dry afterwards and requires more topping off before it's poured properly.

 

We have a Lehman T60 but fill pitchers with slip first when pouring large pots to keep bubbles out of the greenware.  This gives the slip time to deair before it's poured but it needs to be wet enough to give you time to grab another pitcher and continue pouring.We did 80 22" platters that way.

 

I think what you have already poured will be fine but I would mix better and add water before the next pour.