Commenting to second this request. I love how detailed and precise you are with your instructions and would love to see a tutorial on how you slip cast.
wow! exactly what I was looking for. Thank you for passing on your knowledge. I will definitely be following you. You are so detailed in every step it makes it inspiring to try it out!!
I'm glad you found it so informative! I am a professor, after all. :) So, I really want to deliver quality educational material. I'm delighted to hear you are inspired!
Thank you so much for you clear videos! I'm actually translating a course on slip casting and I had no idea how to translate the proper terminology from Spanish into English, but your videos solved all my doubts!
Wow! That's so cool! I understand what you mean. It can be difficult to put into words what we do with our hands. And the adding translation on top of it all must be challenging. I'm glad you found this helpful!
Very nice 40 years I worked with dental plasters Alpha hema hydrates and Beta hema hydrates vacuum mixed and vibrated for a dense fast setting material. Watching how runny a mixture you use is very interesting but all the various plasters used for pottery to dentistry to home building is also interesting gauge plasters moulding #1 and 2 and casting plasters are all different. Thanks for the lecture.
Nope. I generally do not slip cast any work to make it solid as it is more likely to blow up in the kiln. The exception is when casting thin pieces, such as wings or flower petals. Those always cast solid. But they are not truly solid due to the was plaster pulls water out of the clay. There is always inevitably always an air pocket in it. But they never blow up because the air pocket is not large enough. Hope that answers your question!
The shrinkage depends on the type of slip and how high you fire it. Porcelain slip shrinks about 15%. The slip I used in this video only shrinks about 3 or 4% when I fire it at cone 04.
The hummingbird was past the leather-hard stage. So it was quite stable and very firm. And the clay bed was very wet clay. Since there is a discrepancy in the moisture content, the two clays do not wat to stick together (wet clay does not want to stick to dry(ish) clay.
I would just buy some pre-made cone 6 porcelain casting slip. You can get it at most ceramic warehouses and they often come in one-gallon batches. They also come in a variety of colors. Several white colors along with other colors. Good luck!
Dear Rebekah, thanks for these excellent instructions! Started to make a mold of a wooden object. I've a question though. In the second pour the plaste got creamy during mixing, the first time it became creamy after it was poured. Used three minutes soaking and mixing both times. However the slaking went slower the second time and I banged the bucket a couple of times for the plaster to better sink into the mixture. Could this be the reason for the process of thickening being faster? Kind regards, Tom
Hmmm. If I understand you correctly, during the first mixing of the plaster, the plaster was thinner while stirring. And the second time mixing, the plaster was thicker while stirring. And both slaking and mixing time were the same. I would attribute this to having colder water in the first mix and warmer water in the second mix. If the water is warm, it will stiffen much faster. (I am also assuming your water to plaster ratios were identical both times) Perhaps the plaster soaked slower during the second slake because your plaster was a little more condensed into an island shape rather than being more evenly dispersed throughout the bucket. Or it might be due to sprinkling the plaster in a little more slowly during your first mix, thus not creating a large dump of plaster that took longer to absorb. However, my guess is the water temperature. This is where you will see the greatest amount of variation. The warmer the water, the more quickly it will thicken, and it really makes a significant difference. Usually the way you sift your plaster into the water does not make that great of a difference. So, even if you sifted in the plaster differently, I doubt it would make that big of a difference. I hope your mold came out well! Making mold of wooden objects can be a little tricky as the wood swells as it absorbs water from the plaster. So, you have to do both sides as quickly as possible. And wood is porous, so it needs to be coated with Murphy Oil Soap before pouring the plaster over it.
@@rebekahbogard3322 Thanks for your quick and elaborate response! It's probably the temperature of the water I used. The first time I took, approx, 2 l, cold water and had it stand for at least an hour to come at room temperature. The second time I took cold to tepid water and used it soon afterwards. Indeed it is likely that the second the time the water was warmer. Next time I'll make a note of the water temperature before adding the plaster to it. Regards, Tom
The water does not need to be boiled. Sometimes I dilute the Murphy Oil Soap, sometimes I don't. It only takes about 5 min to dry, depending on the humidity level of your environment. I find it is dry by the time I am done mixing my plaster. But I do live in the desert.
Generally speaking, you never want your object to be solid (unless it is tiny). I always drain out the excess slip. A general rule of thumb: if your piece is over an inch thick, it is likely to explode. Of course, there are exceptions to every rule...
Yep. I have used dish-washing soap when I couldn't find my Murphy Oil Soap and it worked just fine. The oil soap is better because it doesn't sud up as you brush it on. But any dish soap should be fine.
You certainly can use modeling clay. But I would recommend water-based modeling clay if you plan to slip cast with it. If you use oil--based clay, the oil in the clay will leach into your plaster and then it would greatly hinder the plaster's ability to act like a sponge and suck up the water (think Scotchgard). When using water-based modeling clay, just make sure you don't let the clay dry out before you add the plaster. If you are not planning to use your mold for slip casting, it doesn't matter if you bed it out with oil based or water based clay. May the force be with you!
I'm glad you liked it! You only need to wear a mask when working with the plaster in it's dry/powder form. Once it slakes up the water, there are no particulates to breathe. I wear a mask when sifting the plaster into the water, and once the air has cleared (which doesn't take long), I remove my mask. By the time it comes to mixing the plaster into the water, it has thoroughly slaked and, again, there are no particulates in the air to worry about.
Thank you Rebekah, you solved (and explained really well) all my doubt about this practice. I only found korean video making molds but couldn't get the precise instructions. Just a question, I have to buy plaster or the procedure is same with alabastrine gypsum? Thank you if you can answer to this too.
You will have to do some research. I'm not familiar with Alabastrine gypsum. The only other plaster I have experience with is Plaster of Paris, which I have used for slip casting. It works, but not well. You could give it a try and see what happens. Let me know how it goes!
Excellent!!! I'm in the process of casting my first lead keel for a model sailboat. I'll be using your techniques for my mold. Can I use a wax instead of, in conjunction with dish soap as a mold release agent?
Hi jj lad. Sorry I am just now getting back to you. No. Do not use wax. It will permeate the mold and you will not be able to get it off. It will prevent the mold from sucking the water out of the slip, thus turning it into clay.
If you can't get Murphy Oil Soap, use any dish soap you have (or even liquid hand soap for that matter). Since the piece you are casting is metal, you do not need to use a mold release on the lead keel. It will release without the mold-release agent. However, if you are making a two-piece mold, you will need to use a mold release agent on the set-up plaster before pouring new plaster on the mold.
Hello from the Dominican Republic :) Thank you so much for all your videos and info Rebekah, they are great!!! I have a question. Here the ceramic materiales are very limited (no specialized stores), they also don't sell pottery plaster, they have 1 plaster which is acceptable for mold making, but I do not know if it is good for slip casting yet. They also do not sell slip so I would have to do it myself. My question: How do you decide if you need to do a MULTI PART PRESS MOLD or a MULTI PART SLIP CASTING MOLD? In my case I am doing sculpture in very small editions, maybe an edition size of 3 for example. Thanks again
Thank you so much for the wonderful compliment! I’m glad my videos are helpful. Your question is a very good one. If I were you, I would start with press molding since it is likely the plaster is not very good for slip casting and, on top of it, you would have to make your own slip. That is quite a lot of work for such small additions. If you decide you want to experiment with slip casting, you could always drill a sprue hole into your mold later (to pour the slip in and out of the the mold). I have done this before with sphere molds which I use both with slip casting and hand building. I usually press or slump mold if I am making something large, and not a lot of the same thing. Or I will press/slump mold if I want the piece to be more substantial and stronger (with thicker walls). I will also press mold when I hand build a piece. I have a collection of various sizes of sphere molds that I slump clay in and then modify it to make heads or oblong shapes. This speeds up my hand building process and makes it more enjoyable as I can power through some of the basic parts of the animal. And slip casting for this method would take way too long. There is a different kind of speed with slump/press molding since you can almost immediately remove the clay from the piece and then keep working with it. My go-to is slip casting when making a lot of things that are small because it is so much faster once the mold is made. I slip cast a lot of birds and flowers. Also, slip casting is great for super smooth surfaces because the clean-up of a piece can take a long time. Slip casting, when you have the proper supplies, is super fast and easy. But slip casting is not always the best solution. Hope that helps!
Just in case you wanted to experiment with slip casting, you can always buy a pre-mixed gallon. www.dickblick.com/products/amaco-no-15-s-casting-slip/?clickTracking=true&wmcp=pla&wmcid=items&wmckw=30511-1009&gclid=CjwKCAjwy42FBhB2EiwAJY0yQnW2WU-LYrRYKFdiHtlk1kzeYBe3afCgOIBG71-FQLkDkz9X04zxoRoC-YAQAvD_BwE
Yep, this is how Christmas tree molds are made. You can buy these molds from Duncan if you do not want to go through the trouble of making a tree out of clay and then casting a plaster mold of them. We have a Duncan Christmas tree mold in our studio at school that was donated to us. My students slip cast several every Christmas to sell as a fundraiser. It is interesting how these trees have come back into fashion.
@@rebekahbogard3322 Lovely to hear from you! Your pieces are so beautiful! 😊 I have acquired a motorized, lighted ceramic Christmas tree. Santa plays peek-a-boo as the top of the tree goes up and down. It is the only one I have ever seen. It's adorable! I've been toying with the idea of recreating it. The motor seems simple enough. I guess I can't safely 'copy' this tree by slip casting it... I would have to design a new tree. It sounds like a huge undertaking to me, but I'm still thinking about it. Happy New Year! 🎉
Yes, you may add gypsum (plaster) to a plaster mold. But you must coat the interior of the mold with a mold release agent (such as Murphy Oil Soap or Vaseline), then put it together, and pour the plaster in. If you do this, you must make sure there are no undercuts, otherwise you will never get the gypsum to release from the plaster. And you do not pour in the gypsum and then pour it back out after a certain amount of time (like you do when slip casting). When casting with plaster, you will be creating a solid object. Good luck!
Actually, thanks for that comment! I was confused by a previous comment by Bionic Ninja. Now I understand. I didn't realize how much I said that! Funny!
Number 1 Pottery Plaster!!!
Wonderful!!
It's the bomb! :)
You are literally the best! Ha I wish you were my teacher! ❤️
omg Becky! I just did a search on how to make a two part mold and your video was the first to pop up. Ha!
Hi Sabrina! Ha! So funny! Thanks for letting me know! I think a lot of professors assign it to their students! :)
Wonderful commentary. Great job. Thank you.
Thanks so much, this is awesome info. I'd love if you continued this series with a tutorial in slip casting.
Commenting to second this request. I love how detailed and precise you are with your instructions and would love to see a tutorial on how you slip cast.
OK! It's on my to do list!
Ditto on what they said ^^
I have made many molds, but you have tought me things I never thought about. Great video!
Wow! That is so good to hear!
Greatest teacher I discovered. Thank you so much for priceless informations you shared🥰❤️
Wow, thank you!
Love this video & how you explained step by step. Makes learning a lot easier
Glad it was helpful!
Thank you for all of your informational videos!
You are so welcome!
What a fantastic tutorial!! Thank you!
wow! exactly what I was looking for. Thank you for passing on your knowledge. I will definitely be following you. You are so detailed in every step it makes it inspiring to try it out!!
I'm glad you found it so informative! I am a professor, after all. :) So, I really want to deliver quality educational material. I'm delighted to hear you are inspired!
Thank you so much for you clear videos! I'm actually translating a course on slip casting and I had no idea how to translate the proper terminology from Spanish into English, but your videos solved all my doubts!
Wow! That's so cool! I understand what you mean. It can be difficult to put into words what we do with our hands. And the adding translation on top of it all must be challenging. I'm glad you found this helpful!
Wow! You've answered all my unanswered questions. Thanks for sharing!
I'm so glad I could help you! Good luck!
This video is a perfect explanation!
Thank you! Glad it was helpful!
Thank you for posting this video. it was very thorough and I learned so much!
Glad it was helpful!
Thank you very much for this lesson you are an excellent teacher it was very clear
You're welcome! Glad it was helpful! Thanks for the compliment!
Brilliant tutorial thank you!
Thank you madame-awsome. great stuff!
Thank you! I love the nickname! I'll have to share it with my students! :)
Very nice 40 years I worked with dental plasters Alpha hema hydrates and Beta hema hydrates vacuum mixed and vibrated for a dense fast setting material. Watching how runny a mixture you use is very interesting but all the various plasters used for pottery to dentistry to home building is also interesting gauge plasters moulding #1 and 2 and casting plasters are all different. Thanks for the lecture.
Wow; that's very interesting! I've only used Plaster of Paris and No 1 Pottery Plaster. Thanks for sharing!
Very good demonstration. Thank you. Do you have a video on casting a solid object... like a fired sculpture piece?
Nope. I generally do not slip cast any work to make it solid as it is more likely to blow up in the kiln. The exception is when casting thin pieces, such as wings or flower petals. Those always cast solid. But they are not truly solid due to the was plaster pulls water out of the clay. There is always inevitably always an air pocket in it. But they never blow up because the air pocket is not large enough. Hope that answers your question!
Thank you very much!! Very helpful.
Glad it was helpful!
Amazing! thank you so much! 🙏
Excellent video
Thank you!
So many excellent tips! Thank you
Thank you! I'm glad to hear you found it so helpful!
great video, great detail. Thank you for putting this together.
Thanks you! Glad it was helpful!
You are a blessing
Thank you! Glad it was helpful!
Oil soap also permeates the plaster like Vaseline aka (thick oil)
Excellent tutorial thanks
Glad it was helpful!
How much shrinkage do you find you are getting, from the original piece to the future ones?
The shrinkage depends on the type of slip and how high you fire it. Porcelain slip shrinks about 15%. The slip I used in this video only shrinks about 3 or 4% when I fire it at cone 04.
This is perfect thank you so much!
Glad you found it helpful!
how did you create the clay bed without marking or damaging the humming bird?
The hummingbird was past the leather-hard stage. So it was quite stable and very firm. And the clay bed was very wet clay. Since there is a discrepancy in the moisture content, the two clays do not wat to stick together (wet clay does not want to stick to dry(ish) clay.
thank you! I want to pour a bowl to match my Rosenthal Baroness fine china. What do I use as a slip to match the fine china?
I would just buy some pre-made cone 6 porcelain casting slip. You can get it at most ceramic warehouses and they often come in one-gallon batches. They also come in a variety of colors. Several white colors along with other colors. Good luck!
Dear Rebekah, thanks for these excellent instructions! Started to make a mold of a wooden object. I've a question though. In the second pour the plaste got creamy during mixing, the first time it became creamy after it was poured. Used three minutes soaking and mixing both times. However the slaking went slower the second time and I banged the bucket a couple of times for the plaster to better sink into the mixture. Could this be the reason for the process of thickening being faster?
Kind regards,
Tom
Hmmm. If I understand you correctly, during the first mixing of the plaster, the plaster was thinner while stirring. And the second time mixing, the plaster was thicker while stirring. And both slaking and mixing time were the same. I would attribute this to having colder water in the first mix and warmer water in the second mix. If the water is warm, it will stiffen much faster. (I am also assuming your water to plaster ratios were identical both times)
Perhaps the plaster soaked slower during the second slake because your plaster was a little more condensed into an island shape rather than being more evenly dispersed throughout the bucket. Or it might be due to sprinkling the plaster in a little more slowly during your first mix, thus not creating a large dump of plaster that took longer to absorb.
However, my guess is the water temperature. This is where you will see the greatest amount of variation. The warmer the water, the more quickly it will thicken, and it really makes a significant difference. Usually the way you sift your plaster into the water does not make that great of a difference. So, even if you sifted in the plaster differently, I doubt it would make that big of a difference.
I hope your mold came out well! Making mold of wooden objects can be a little tricky as the wood swells as it absorbs water from the plaster. So, you have to do both sides as quickly as possible. And wood is porous, so it needs to be coated with Murphy Oil Soap before pouring the plaster over it.
@@rebekahbogard3322 Thanks for your quick and elaborate response! It's probably the temperature of the water I used. The first time I took, approx, 2 l, cold water and had it stand for at least an hour to come at room temperature. The second time I took cold to tepid water and used it soon afterwards. Indeed it is likely that the second the time the water was warmer. Next time I'll make a note of the water temperature before adding the plaster to it.
Regards,
Tom
You don't mention drying time for the murphy's oil soap nor if you diluted it w/50% boiled water. Can you please clarify? Thanks
The water does not need to be boiled. Sometimes I dilute the Murphy Oil Soap, sometimes I don't. It only takes about 5 min to dry, depending on the humidity level of your environment. I find it is dry by the time I am done mixing my plaster. But I do live in the desert.
When you slip cast for this type of mold do you drain out the excess slip or continue filling it to have a solid product?
Generally speaking, you never want your object to be solid (unless it is tiny). I always drain out the excess slip. A general rule of thumb: if your piece is over an inch thick, it is likely to explode. Of course, there are exceptions to every rule...
thank you. very helpful
You're welcome!
Aside from the oil soap that you use, is the regular dishwashing soap works?
Yep. I have used dish-washing soap when I couldn't find my Murphy Oil Soap and it worked just fine. The oil soap is better because it doesn't sud up as you brush it on. But any dish soap should be fine.
Hi Rebekah! Very helpful video! What kind of clay body is used for the clay bed? Can i use regular modelling clay so it wont harden?
You certainly can use modeling clay. But I would recommend water-based modeling clay if you plan to slip cast with it. If you use oil--based clay, the oil in the clay will leach into your plaster and then it would greatly hinder the plaster's ability to act like a sponge and suck up the water (think Scotchgard). When using water-based modeling clay, just make sure you don't let the clay dry out before you add the plaster.
If you are not planning to use your mold for slip casting, it doesn't matter if you bed it out with oil based or water based clay.
May the force be with you!
@@rebekahbogard3322 Thank you so so much!
very informative , oh and i love your hair. that is all. :D
Ahh, that's so nice! What an unexpected compliment on my hair! :) I'm also glad you found the video informative!
Amazing video thank you! But please wear a mask when your arms the plaster
I'm glad you liked it! You only need to wear a mask when working with the plaster in it's dry/powder form. Once it slakes up the water, there are no particulates to breathe. I wear a mask when sifting the plaster into the water, and once the air has cleared (which doesn't take long), I remove my mask. By the time it comes to mixing the plaster into the water, it has thoroughly slaked and, again, there are no particulates in the air to worry about.
Thank you Rebekah, you solved (and explained really well) all my doubt about this practice. I only found korean video making molds but couldn't get the precise instructions. Just a question, I have to buy plaster or the procedure is same with alabastrine gypsum? Thank you if you can answer to this too.
You will have to do some research. I'm not familiar with Alabastrine gypsum. The only other plaster I have experience with is Plaster of Paris, which I have used for slip casting. It works, but not well. You could give it a try and see what happens. Let me know how it goes!
what’s the material of ur table top? such that u can roll clay right on it?
I'm not sure; it's some sort of plastic. Years of experience makes me good at rolling out clay on non-porous surfaces. :)
Can you make a mold using a bisque piece?
Yes. If it is not glazed, coat the bisqueware with Murphy's Oil Soap
Excellent!!! I'm in the process of casting my first lead keel for a model sailboat. I'll be using your techniques for my mold. Can I use a wax instead of, in conjunction with dish soap as a mold release agent?
Hi jj lad. Sorry I am just now getting back to you. No. Do not use wax. It will permeate the mold and you will not be able to get it off. It will prevent the mold from sucking the water out of the slip, thus turning it into clay.
If you can't get Murphy Oil Soap, use any dish soap you have (or even liquid hand soap for that matter). Since the piece you are casting is metal, you do not need to use a mold release on the lead keel. It will release without the mold-release agent. However, if you are making a two-piece mold, you will need to use a mold release agent on the set-up plaster before pouring new plaster on the mold.
Just a note, did Murphy oil soap sponsor this video? You say it about 40 times
Nope. But I do love Murphy Oil Soap! :)
Thank you!
You're welcome!
Hello from the Dominican Republic :)
Thank you so much for all your videos and info Rebekah, they are great!!!
I have a question. Here the ceramic materiales are very limited (no specialized stores), they also don't sell pottery plaster, they have 1 plaster which is acceptable for mold making, but I do not know if it is good for slip casting yet. They also do not sell slip so I would have to do it myself.
My question: How do you decide if you need to do a MULTI PART PRESS MOLD or a MULTI PART SLIP CASTING MOLD? In my case I am doing sculpture in very small editions, maybe an edition size of 3 for example.
Thanks again
Thank you so much for the wonderful compliment! I’m glad my videos are helpful. Your question is a very good one.
If I were you, I would start with press molding since it is likely the plaster is not very good for slip casting and, on top of it, you would have to make your own slip. That is quite a lot of work for such small additions. If you decide you want to experiment with slip casting, you could always drill a sprue hole into your mold later (to pour the slip in and out of the the mold). I have done this before with sphere molds which I use both with slip casting and hand building.
I usually press or slump mold if I am making something large, and not a lot of the same thing. Or I will press/slump mold if I want the piece to be more substantial and stronger (with thicker walls). I will also press mold when I hand build a piece. I have a collection of various sizes of sphere molds that I slump clay in and then modify it to make heads or oblong shapes. This speeds up my hand building process and makes it more enjoyable as I can power through some of the basic parts of the animal. And slip casting for this method would take way too long. There is a different kind of speed with slump/press molding since you can almost immediately remove the clay from the piece and then keep working with it.
My go-to is slip casting when making a lot of things that are small because it is so much faster once the mold is made. I slip cast a lot of birds and flowers. Also, slip casting is great for super smooth surfaces because the clean-up of a piece can take a long time. Slip casting, when you have the proper supplies, is super fast and easy. But slip casting is not always the best solution.
Hope that helps!
Just in case you wanted to experiment with slip casting, you can always buy a pre-mixed gallon. www.dickblick.com/products/amaco-no-15-s-casting-slip/?clickTracking=true&wmcp=pla&wmcid=items&wmckw=30511-1009&gclid=CjwKCAjwy42FBhB2EiwAJY0yQnW2WU-LYrRYKFdiHtlk1kzeYBe3afCgOIBG71-FQLkDkz9X04zxoRoC-YAQAvD_BwE
@@rebekahbogard3322 Thank you so much for such a detailed and thorough answer. :) xxx
Great work
Hi Rebekah. Great video! How are lighted ceramic Christmas tree molds made? Are the trees designed in clay first? Thank you. 😊
Yep, this is how Christmas tree molds are made. You can buy these molds from Duncan if you do not want to go through the trouble of making a tree out of clay and then casting a plaster mold of them. We have a Duncan Christmas tree mold in our studio at school that was donated to us. My students slip cast several every Christmas to sell as a fundraiser. It is interesting how these trees have come back into fashion.
@@rebekahbogard3322
Lovely to hear from you! Your pieces are so beautiful! 😊 I have acquired a motorized, lighted ceramic Christmas tree. Santa plays peek-a-boo as the top of the tree goes up and down. It is the only one I have ever seen. It's adorable! I've been toying with the idea of recreating it. The motor seems simple enough. I guess I can't safely 'copy' this tree by slip casting it... I would have to design a new tree. It sounds like a huge undertaking to me, but I'm still thinking about it. Happy New Year! 🎉
Hello mam
Can we cast gypsum in such mold ??
Does gupsum casting give same result as clay casting mold like that shown in vdo
Yes, you may add gypsum (plaster) to a plaster mold. But you must coat the interior of the mold with a mold release agent (such as Murphy Oil Soap or Vaseline), then put it together, and pour the plaster in. If you do this, you must make sure there are no undercuts, otherwise you will never get the gypsum to release from the plaster. And you do not pour in the gypsum and then pour it back out after a certain amount of time (like you do when slip casting). When casting with plaster, you will be creating a solid object. Good luck!
@@rebekahbogard3322 lots of love
Thank you 😊
is there a part 3?
Nope. Is there something specific you were hoping to learn?
Can I use liquid soap as release agent?
Same question.
Yes, it should work just fine. Like dish soap, it gets foamy. But it will still work.
@@rebekahbogard3322 hey so um, do i have to wash the plaster mold afterwards? To get the soap off...
@@volstrekt Yes. She mentioned she used vinegar on her sponge and water to clean the soap off.
@@bunch8 i used petroleum jelly.. i made a drip mold btw.. do i have to wash it off as well?
thanks 🌷🌷💗
Please disregard comment about the oil soap, happy holidays.
Actually, thanks for that comment! I was confused by a previous comment by Bionic Ninja. Now I understand. I didn't realize how much I said that! Funny!
Line your cottle boards with a plastic bag, faster water tight seal
thank you!!!!
You're welcome!
Murphy oil soap
You said it! :) (And so did I!)
another grand grand grand daughter of Leonardo Da Vinci
Well, I wouldn't go that far! But you just made my day!!!