Hester Posted October 12, 2018 Report Share Posted October 12, 2018 I recently began experimenting slip casting using commercial molds. One particular mold, the handle of the cup ,which is a neat little circle gets stuck everytime I take it out and then it breaks off. Is there a release agent I can use that will make the releasing process easier without hampering the osmosis between the clay and the plaster. Please advise ?? Link to comment Share on other sites More sharing options...
Chilly Posted October 12, 2018 Report Share Posted October 12, 2018 No release agent for plaster moulds, that I know of. Have you checked that the mould is clean? Try vinegar and a sponge to clean it up. Does your slip release easily from other moulds? Are you leaving it too long before un-moulding? Too little time? Casting too thick, too thin? Small curved moulds are the devil to deal with. I have had to enlarge the "funnel" on handle moulds as they never held enough "top-up" slip. Link to comment Share on other sites More sharing options...
Hester Posted October 12, 2018 Author Report Share Posted October 12, 2018 Thanks for your reply . I did leave the mold overnight for the slip to harden properly maybe the slip shrank too much. I just have to keep on trying to get the timing right and will use some vinegar for cleaning Link to comment Share on other sites More sharing options...
Pres Posted October 13, 2018 Report Share Posted October 13, 2018 I will be moving this thread to Studio Operations and Making Work, as it will be more appropriate. best, Pres Link to comment Share on other sites More sharing options...
Mark C. Posted October 13, 2018 Report Share Posted October 13, 2018 That cup handle is often cast alone and added later. The tricks are dry mold very well before use-after dumping it our pull it apart when cup is ready-time this on a timer. Do not leave overnight-take it apart when clay in handle has some give to it. The reason its cracking is is shrinking onto the inside cast part of the handle.The idea is to get it out before it grabs the inner part.This type of cup with handle is a hard top deal with mold to get a handle cast to body in one pour. many cup molds added the handle later as that is easier. Link to comment Share on other sites More sharing options...
Hester Posted October 15, 2018 Author Report Share Posted October 15, 2018 Thanks Mark for your advice.I did attach the cracked off handles with some casting slip and I am surprised how well it binds after dipping the cup quickly in water.Just hope it will survive the firing. I also have another mold I want to use .It is a candle holder but it does not have a pouring cup .How do you cast that one?.Do you fill the one half with slip, put the other half on top and rotate it to get an even layer inside.?Please advise it is like casting blindfolded. Link to comment Share on other sites More sharing options...
Mark C. Posted October 15, 2018 Report Share Posted October 15, 2018 I have no idea on a mold without a pouring hole. It could be a press mold -you do each 1/2 and attach them together -just a guess. You could always make a hole into mold as plaster is soft. Link to comment Share on other sites More sharing options...
Chilly Posted October 18, 2018 Report Share Posted October 18, 2018 Hi @Hester Can you post some pictures of the mould, showing the whole thing, and just one half? Link to comment Share on other sites More sharing options...
Hester Posted October 28, 2018 Author Report Share Posted October 28, 2018 I will do . Try to a bit techno retard. Link to comment Share on other sites More sharing options...
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