Little Bike Posted July 6, 2017 Report Share Posted July 6, 2017 I found a great styrofoam bowl shape and proceeded to paddle a slab over it this afternoon then couldn't get the clay to release. Would a liberal coating of corn starch have worked or? Thanks Link to comment Share on other sites More sharing options...
Sputty Posted July 6, 2017 Report Share Posted July 6, 2017 . Link to comment Share on other sites More sharing options...
Marcia Selsor Posted July 6, 2017 Report Share Posted July 6, 2017 Corn starch will work. I usually put a thin coat of plaster on styrofoam molds. I think plaster is one of the best surfaces for molds. I learned this from my teacher, Bill Daley. https://www.pinterest.com/pin/231372499580729819/ He is still making pots. Marcia Link to comment Share on other sites More sharing options...
GEP Posted July 6, 2017 Report Share Posted July 6, 2017 I make and use a lot of plaster-coated styrofoam molds too. However, during the stage when I am still tweeking and testing the shape of the mold, I wrap the mold Glad Press-n-Seal. The Press-n-Seal will release easily from the styrofoam, then it can be peeled away from the clay. So if you don't want to pour plaster over your mold, this is another option. Link to comment Share on other sites More sharing options...
Little Bike Posted July 6, 2017 Author Report Share Posted July 6, 2017 Thanks all for all the techniques! Link to comment Share on other sites More sharing options...
Little Bike Posted July 6, 2017 Author Report Share Posted July 6, 2017 Corn starch will work. I usually put a thin coat of plaster on styrofoam molds. I think plaster is one of the best surfaces for molds. I learned this from my teacher, Bill Daley. https://www.pinterest.com/pin/231372499580729819/ He is still making pots. Marcia Thanks for the link - really interesting pieces! I like! Link to comment Share on other sites More sharing options...
Min Posted July 6, 2017 Report Share Posted July 6, 2017 I would normally reach for the talc. Seems to work for most materials. psst, save your lungs and reach for the cornstarch / cornflour instead, not a good idea to be dusting things with talc. Link to comment Share on other sites More sharing options...
PSC Posted July 7, 2017 Report Share Posted July 7, 2017 Vegetable oil...i use vegetable oil as a mold release on most everything non porous Link to comment Share on other sites More sharing options...
Mark C. Posted July 7, 2017 Report Share Posted July 7, 2017 I use l mold soap (lube) fore all release work if it looks sticky. I have some oval platters made from plastic and this lube works great. no starch needed. Link to comment Share on other sites More sharing options...
oldlady Posted July 7, 2017 Report Share Posted July 7, 2017 mark, could you please identify the mysterious "mold soap" by brand name and any other specific directions so i can purchase the same thing? this is one of the things i have never been able to find though i have lots of products that people think are "mold soap" but do not work. a photo would be grand but i know you think you have used up all your photo space. maybe in the gallery? no limit there. Link to comment Share on other sites More sharing options...
Mark C. Posted July 8, 2017 Report Share Posted July 8, 2017 Here is the link with a photo-I buy it in the gallon size but it comes in pints as well. I use it on plastic forms or wooden forms. I use it on forms that I pour plaster on as well unless its the below stuff.. http://www.axner.com/search.aspx?find=lube mold lube or mold soap-I put it on with dampened sponge. If you want to seal a surface permanently like say plaster to pour more plaster onto and get its to release or say a wood form that you want sealed to make a mold from use Polyurethane Parting compound . I have had my gallon since time began so you will have to source it on your own-it seals the surface with a smooth rubbery surface. I use it to make a plaster mold from a plaster mold pouring plaster onto plaster . One you have used the PPC cannot undo that surface meanings its always sealed-so do not use on any paster form you want to apply clay to. I learned all this from a good friend I knew for 30 years-he was a master mold maker-pots to architectural work for 40 years . He was a true master plaster worker.He is dead now-I leaned all my better mold skills from him vs my art collage where they taught strange ways to work with plaster that later I learned where all wrong. Oldlady I cleared out some old photos and now have been posting new ones like crazy-like my 4th of July booth and pottery racks I know others in this forum like grocery store items to use in place of the real stuff - like shoe polish and lemon oil but this is the real product for these jobs-they cost about the same as your bottle of cooking oil and a box of cornstarch. If you want to save money make your own car tires from kids ballons and duct tape. Link to comment Share on other sites More sharing options...
oldlady Posted July 8, 2017 Report Share Posted July 8, 2017 thank you, mark. i will need new tires before i go to florida this year so i might try your idea. cannot wait to try the mold release or lube. first i have to decide what to buy to add up to $10 since axner will not sell less than that. hmmm, what do i need? they only hold a year of photos in that numeric limit so you automatically earn space for more. don't ask, math is not my subject and calendars are numbers in disguise. Link to comment Share on other sites More sharing options...
Mark C. Posted July 8, 2017 Report Share Posted July 8, 2017 1:40 am-you need to get some sleep. Link to comment Share on other sites More sharing options...
PSC Posted July 9, 2017 Report Share Posted July 9, 2017 I know others in this forum like grocery store items to use in place of the real stuff - like shoe polish and lemon oil but this is the real product for these jobs-they cost about the same as your bottle of cooking oil and a box of cornstarch. If you want to save money make your own car tires from kids ballons and duct tape. I've been using the same bottle of veggie oil for a decade now...yep its a bit rancid but it was rancid when i moved it from the kitchen to the studio...waste not want not. And i don't have to pay shipping, nor axner's 3.95 handling fee or wait to meet their $10 minimum lol It works. Link to comment Share on other sites More sharing options...
Mark C. Posted July 9, 2017 Report Share Posted July 9, 2017 Oil will clog plaster surface over time. Oil will affect the plaster in a negative way in any working mold.A better option is green soap at the drug store-any good drug store. Now I will add I bought my bottle of green soap in the 70's-still have it on the shelve. In the course of every year I often buy a few hundred dollars from various ceramic suppliers (besides my 20 ton order from Laguna).Just the cost of doing business. Never had to consider a minimum in terms of ceramic materials. I have no small user perspective on costs-If I did I still would work towards doing things the best way. I just think oil is not good for plaster-yes it will work. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted July 9, 2017 Report Share Posted July 9, 2017 In ancient times we used Murphy's soap for mold soap in Art school. used it for mold release when casting things in plaster.Iagree with mark about the oil not being the best thing to use on plaster. WD 40 is a good release and good to use on extruders before using. Makes for very fast clean up...if you can stand the smell. Marcia Link to comment Share on other sites More sharing options...
Mark C. Posted July 9, 2017 Report Share Posted July 9, 2017 One of the basic things about plaster is it works well with clay because it sucks the water from the clay -hence it dries out clay. It transfers clay moisture to itself -than you dry out the plaster and do it again. That said its best to use materials (soaps-oil whatever that are water based) this is because oil or petroleum products will clog the pores and seal the surface making it less absorbent over time.As the plaster seals up it will not absorb or dry as well. All the household products you may use -look for ones that are all water based.You will get more life out of your plaster. Link to comment Share on other sites More sharing options...
Little Bike Posted July 10, 2017 Author Report Share Posted July 10, 2017 Eventually I'll make plaster molds for shapes I know I'll want to repeat, for now I went with a bag from a dry cleaners. Link to comment Share on other sites More sharing options...
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