Excellent! One tool I use that helps with handling internal bubbles and avoiding sneaky lumps is a small kitchen strainer. I pour through that, just as with the slip, and it helps with consistent surfaces. 😁
Thanks! I hadn't seen that one before. In these recent experiments I've found that mixing volume has had once of the largest impacts in reducing bubbles (having enough liquid so they don't get sucked in).
A side by side 2 piece mold could work with the concavity at the bottom. The sides would need to pull away down and to the side. 8:38 happens to have the camera along a suitable pull angle.
Thanks. Yes, that is a good point. I think my brain automatically goes to pulling perpendicular to the plaster mating surface. But that doesn't need to be the case!
I love mold-making. Good thought process. Another option was to eliminate the bottom foot, smooth-in with clay, and do two piece mold. Then use a round utensil to hammer in a foot indent after pulling out the form. Wouldn't be as precise but it would look better imo than an obviously mass-produced foot. Of course you were doing this as an example so no artistic judgement 😂
The glass only had two molds, the bottom indent was added after the hot pieces were pushed together, and a stamp pushed up and deformed the combined glass.
I have not used them. I played around with 3D printing some, but they didn't work in the way I wanted. I'm still on the fence about having keys vs not having any - there are tradeoffs.
@PotterybyKent I watched a video about 3D printed keys recently. The positive and negative keys cannot be the exact same size. The negative side needs to be a bit larger. I have made two 3D printed molds so far, and had problems with both. Errors in printing compounded with errors in mold making made my plaster pieces not fit together causing leaking. I would be interested in seeing any solutions for these problems. Thanks!
Correct, they can't be the same size when printed. For my Shape Cast handle molds, I have keys but they also have a tolerance built in. As such they are there for rough alignment. The other issue with printed surfaces is they often aren't flat which can also cause leaking between the final mold parts. Lapping is one solution here (but keys would get in the way of that).
Thank you for your works..are amazing.. Your videos are very simple to be understand for everyone...I am a begginer to this kind of work and I have a challenge about one mold: can you tell me please what kind of mold must be made for a V 60 coffee dripper?...If can you please make a video about this mold... Thanks and more wonderful videos and moulds 🎉❤
What if you need a shape with a hollow tube running through the middle? For example, a cone shape with a flat bottom with a hole in the center and a tube going to the top. I recently tried to make something like this with a one piece mold, because, like your first examples, a cone has a suitable draft angle. But, as I discovered, having a plaster cylinder in the center for the tube makes the clay slip shrink towards it, locking it into the mold, so obviously that doesn't work, and also, with a one piece mold, the bottom of the cone would be open. Would it be possible using a multi-part mold to make this object in one piece? Or will I have to make it in pieces and join them together like I'm doing currently? Thanks!
As you found, this type of geometry is indeed hard to do with slip casting and is likely dependent on the details of the form. I have seen successful double walled bowls and mugs which have an inner plaster part in a similar way. I think part of this is also size dependent (something smaller will shrink less in terms of absolute size - eg 10% of 10mm vs 10% of 100mm). You could also play with the clay body as they have different shrinkage rates.
I was wondering, is it possible to make a slip casting with a more complex shame like an indentation of a logo or some other shapes on the model? I have some experience casting things out of plaster, candle wax, and soap, but 0 with slip casting and ceramics.
Yes you can! And many people do that, for example having their logo embedded in the foot. One thing you really need to consider are the draft angles and making sure there are no overhangs.
Hello! Thank you for making these very informative video! I want to cast a small sculpture I sculpted out of DAS air-hardening modeling clay. Will this work using your method of making a mold here? I haven't painted or treated the surface of the sculpture with anything. Thank you, Daniel
The first consideration is that there are no undercuts. Also, I don't know about the material - it could work however there is always a risk of losing the master. You probably want to do a test with another form if you're worried at all.
How would you make a mold for the classic vase shape that starts small at the bottom, gets bigger in the middle, smaller at the collar, and then bigger at the mouth? Like this (if the formatting works): \ / / \ \ /
Depending on the foot, you would just split it vertically instead of horizontally (eg as I discuss at 4:00). The same overall process would work. If the foot would get trapped, then you might need a 3 part mold - one for the foot and then the 2 sides.
I don't think cement will work. I keep mine in for about 30 minutes but you need to experiment with your molds and slip to find a timing that works for you.
I have wondered about possibly adding some white cement to my plaster to increase strength. I'm not sure how that would affect the porosity and absorptivness of the mold. Commercial molds seem harder and more durable than mine ever are, so I'm wondering what they are doing to make them that way.
Those two are not linked in that way, so this is really two different questions. The first question is how much water is in the slip - follow the manufacturers recommendation (mine is 30% water by weight). Then the second question is how long to wait. That depends on a bunch of factors like your mold, how humid and warm it is, etc. So the best thing to do is test it and see. If the walls are too thin, wait longer next time and vice versa. Similarly for demanding, you can tell when it's ready when its release from the mold. And if it hasen't yet, wait longer.
It depends on why it won't release. For example, did you accidentally create an undercut? In that case there's not much you can do besides break the plaster and try again. Sometimes I've found once things are cool, it is easier to get out. I've also had to destroy the original (usually a 3D printed part). At this point with my 3D printed molds I use a mixture of frozen alcohol and water to slightly shrink the plastic - you might try that as well.
great video! i'm new to this and I'm a little confused, what liquid material is used for the slip? is it just plaster, or is it specifically made for slip casting?
The material to make the plaster mold that I use is specifically formulated for use with ceramics. In particular it is USG #1 Pottery Plaster. As far as the slip itself, the clay composition is different than throwing clay, but I haven't dug into the details and I get it from my pottery supply store.
A newbie here as well trying to figure out the liquids.. Did I understand correct that the mold itself is made of modeling plaster (modelgips in Dutch)? Also wonder if this technique can be used to make mold from a clay sculpture and then make a plaster copy to have it lighter and to sand the imperfections afterwards? Many thanks!
@@caglakaplan1748 Yes, the mold is plaster - it is specifically design for pottery use like slip casting (other plaster might work but I don't know). One traditional way to do this is to make a plaster mold of a clay form. I think you're asking about making a plaster object from the mold - that might be tricky as plaster likes to stick to itself and is very rigid - but again I haven't tried myself.
@@PotterybyKentmaybe wrapping the interior of the mold with plastic wrap? If you’re careful, you may be able to lightly sand out any fold lines left by the plastic wrap.
@@caglakaplan1748 I have mistakenly purchased USG #1 Molding Plaster instead of USG #1 Pottery Plaster. It's a different formulation but it seemed to still work well for slip casting. The recommended is the Pottery Plaster. This method is not for making plaster copies.
Kent that moment when you were able to separate the two halfs was so suspenseful! I cheered when you were able to successfully use your two part mold!
I wasn't sure it would for a bit!
Excellent! One tool I use that helps with handling internal bubbles and avoiding sneaky lumps is a small kitchen strainer. I pour through that, just as with the slip, and it helps with consistent surfaces. 😁
Thanks! I hadn't seen that one before. In these recent experiments I've found that mixing volume has had once of the largest impacts in reducing bubbles (having enough liquid so they don't get sucked in).
Pędzelkiem się dpowietrza
@@epidian6240 - Не всегда, в отрицательных углах не удаляется.
This is a great video, and so interesting. Thank you for sharing your method :)
Thanks for watching!
+1 в карму!
Супер гуд, очень хорошо объясняешь,
даже для тех, у кого плохо с геометрией.
Thanks for watching!
A side by side 2 piece mold could work with the concavity at the bottom. The sides would need to pull away down and to the side. 8:38 happens to have the camera along a suitable pull angle.
Thanks. Yes, that is a good point. I think my brain automatically goes to pulling perpendicular to the plaster mating surface. But that doesn't need to be the case!
Brilliant thank you
You're very welcome!
your videos are awesome, thanks
Glad you like them!
I love mold-making. Good thought process. Another option was to eliminate the bottom foot, smooth-in with clay, and do two piece mold. Then use a round utensil to hammer in a foot indent after pulling out the form. Wouldn't be as precise but it would look better imo than an obviously mass-produced foot. Of course you were doing this as an example so no artistic judgement 😂
Yep, just a demo for sure! But it is a great point that you can modify forms to suit your needs like that.
Залей таким способом лампочку.
Muito obrigado pela aula sua voz é calma facilita entender e é muito bela também
Thanks for watching!
The glass only had two molds, the bottom indent was added after the hot pieces were pushed together, and a stamp pushed up and deformed the combined glass.
Thanks. It is plastic, but that would make sense.
Another informative video, thanks 😊
Glad you enjoyed it!
Forma kiepska , zrobiona amatorsko musisz się jeszcze wiele nauczyć
thanks to much👍
You're welcome!
Love all your videos, thanks for taking the time to share. I see some people use those pre-made keys. Have you ever used them?
I have not used them. I played around with 3D printing some, but they didn't work in the way I wanted. I'm still on the fence about having keys vs not having any - there are tradeoffs.
@PotterybyKent I watched a video about 3D printed keys recently. The positive and negative keys cannot be the exact same size. The negative side needs to be a bit larger.
I have made two 3D printed molds so far, and had problems with both. Errors in printing compounded with errors in mold making made my plaster pieces not fit together causing leaking. I would be interested in seeing any solutions for these problems. Thanks!
Correct, they can't be the same size when printed. For my Shape Cast handle molds, I have keys but they also have a tolerance built in. As such they are there for rough alignment. The other issue with printed surfaces is they often aren't flat which can also cause leaking between the final mold parts. Lapping is one solution here (but keys would get in the way of that).
Thank you for your works..are amazing.. Your videos are very simple to be understand for everyone...I am a begginer to this kind of work and I have a challenge about one mold: can you tell me please what kind of mold must be made for a V 60 coffee dripper?...If can you please make a video about this mold... Thanks and more wonderful videos and moulds 🎉❤
Thanks so much! I don't use a V60 myself but have seen a few. It would be a multipart mold for sure!
Cool thanks !!
No problem!
What if you need a shape with a hollow tube running through the middle? For example, a cone shape with a flat bottom with a hole in the center and a tube going to the top.
I recently tried to make something like this with a one piece mold, because, like your first examples, a cone has a suitable draft angle. But, as I discovered, having a plaster cylinder in the center for the tube makes the clay slip shrink towards it, locking it into the mold, so obviously that doesn't work, and also, with a one piece mold, the bottom of the cone would be open.
Would it be possible using a multi-part mold to make this object in one piece? Or will I have to make it in pieces and join them together like I'm doing currently?
Thanks!
As you found, this type of geometry is indeed hard to do with slip casting and is likely dependent on the details of the form. I have seen successful double walled bowls and mugs which have an inner plaster part in a similar way. I think part of this is also size dependent (something smaller will shrink less in terms of absolute size - eg 10% of 10mm vs 10% of 100mm). You could also play with the clay body as they have different shrinkage rates.
What type of foam are you using
Here I used extruded polystyrene
انني ممتنة لك على مجهودك الجميل سيدي هل يمكنك ان تعطيني مقدار خلطة الجص من ماء وجص لكي اتأكد ان القالب لا يتكسر اتناء الاستعمال
It's 70 parts plaster to 30 water
I was wondering, is it possible to make a slip casting with a more complex shame like an indentation of a logo or some other shapes on the model? I have some experience casting things out of plaster, candle wax, and soap, but 0 with slip casting and ceramics.
Yes you can! And many people do that, for example having their logo embedded in the foot. One thing you really need to consider are the draft angles and making sure there are no overhangs.
Hello! Thank you for making these very informative video! I want to cast a small sculpture I sculpted out of DAS air-hardening modeling clay. Will this work using your method of making a mold here? I haven't painted or treated the surface of the sculpture with anything. Thank you, Daniel
The first consideration is that there are no undercuts. Also, I don't know about the material - it could work however there is always a risk of losing the master. You probably want to do a test with another form if you're worried at all.
How would you make a mold for the classic vase shape that starts small at the bottom, gets bigger in the middle, smaller at the collar, and then bigger at the mouth? Like this (if the formatting works):
\ /
/ \
\ /
Depending on the foot, you would just split it vertically instead of horizontally (eg as I discuss at 4:00). The same overall process would work. If the foot would get trapped, then you might need a 3 part mold - one for the foot and then the 2 sides.
Can you use a plastic bucket instead of wood ?
Yes!
هل يمكنك ان تذكر المواد المستعملة مع ذكر مقادير الخلط
USG #1 Pottery plaster
Can we use white cement instead of Plaster? and how long do we keep liquid in the mold before pour out?
I don't think cement will work. I keep mine in for about 30 minutes but you need to experiment with your molds and slip to find a timing that works for you.
I have wondered about possibly adding some white cement to my plaster to increase strength. I'm not sure how that would affect the porosity and absorptivness of the mold.
Commercial molds seem harder and more durable than mine ever are, so I'm wondering what they are doing to make them that way.
How much water do you mix with the clay to know that 30 minutes is sufficient drying?
Those two are not linked in that way, so this is really two different questions. The first question is how much water is in the slip - follow the manufacturers recommendation (mine is 30% water by weight). Then the second question is how long to wait. That depends on a bunch of factors like your mold, how humid and warm it is, etc. So the best thing to do is test it and see. If the walls are too thin, wait longer next time and vice versa. Similarly for demanding, you can tell when it's ready when its release from the mold. And if it hasen't yet, wait longer.
Thanks for the quick and detailed response, makes sense :)
White plaster meaning? white cement or Pop?
Pottery plaster
@@PotterybyKent thanks brother
What if my object won’t release?! 😢
It depends on why it won't release. For example, did you accidentally create an undercut? In that case there's not much you can do besides break the plaster and try again. Sometimes I've found once things are cool, it is easier to get out. I've also had to destroy the original (usually a 3D printed part). At this point with my 3D printed molds I use a mixture of frozen alcohol and water to slightly shrink the plastic - you might try that as well.
great video! i'm new to this and I'm a little confused, what liquid material is used for the slip? is it just plaster, or is it specifically made for slip casting?
The material to make the plaster mold that I use is specifically formulated for use with ceramics. In particular it is USG #1 Pottery Plaster.
As far as the slip itself, the clay composition is different than throwing clay, but I haven't dug into the details and I get it from my pottery supply store.
A newbie here as well trying to figure out the liquids.. Did I understand correct that the mold itself is made of modeling plaster (modelgips in Dutch)? Also wonder if this technique can be used to make mold from a clay sculpture and then make a plaster copy to have it lighter and to sand the imperfections afterwards?
Many thanks!
@@caglakaplan1748 Yes, the mold is plaster - it is specifically design for pottery use like slip casting (other plaster might work but I don't know).
One traditional way to do this is to make a plaster mold of a clay form. I think you're asking about making a plaster object from the mold - that might be tricky as plaster likes to stick to itself and is very rigid - but again I haven't tried myself.
@@PotterybyKentmaybe wrapping the interior of the mold with plastic wrap? If you’re careful, you may be able to lightly sand out any fold lines left by the plastic wrap.
@@caglakaplan1748 I have mistakenly purchased USG #1 Molding Plaster instead of USG #1 Pottery Plaster. It's a different formulation but it seemed to still work well for slip casting. The recommended is the Pottery Plaster.
This method is not for making plaster copies.
can you do plates?
Yes. I haven't tried doing them myself yet, but have seen two part molded plates (cast solid).
line the cottle boards with a plastic bag - guaranteed not to leak. An much easier to get a water tight seal than tape, clay, etc.
Interesting idea. I did that for a bit with my plate bucket - but it can get a tear that way so I stopped. And now, I much prefer my 3d printed molds!