Two Part Plaster Mold for Slip Casting

Рет қаралды 20,812

Жыл бұрын

Here I show making a two part plaster mold so we can make a copy of more complex shapes. In particular we can move beyond forms that have a draft angle from top to bottom.
This is the fourth in a series of videos where I'm going to do a deep dive into plaster mold making for slip casting. We'll iterate through different approaches with the end goal of creating some software that can do most of the hard work of mold design for us!
TOOLS & MATERIALS (affiliate)
- 1 Gallon Buckets (plaster form) amzn.to/3OTcQ3o
- Drill Attachment Mixer amzn.to/3OP9iiv
- Murphy Oil Soap (mold release) amzn.to/3MQEWtm
- Bar clamps (for cottle boards) amzn.to/3X2HZTV
- Hot wire foam cutter (for slip well) amzn.to/43QoFeL
- The Essential Guide to Mold Making & Slip Casting amzn.to/3OV2TCw

Пікірлер: 52

@theabristlebroom4378 Жыл бұрын

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!

@PotterybyKent Жыл бұрын

I wasn't sure it would for a bit!

@Bob-Is-A-PotterNow Жыл бұрын

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. 😁

@PotterybyKent Жыл бұрын

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).

@epidian6240 8 ай бұрын

Pędzelkiem się dpowietrza

@esme765 7 ай бұрын

your videos are awesome, thanks

@PotterybyKent 7 ай бұрын

Glad you like them!

@malcolm7436 5 ай бұрын

This is a great video, and so interesting. Thank you for sharing your method :)

@PotterybyKent 5 ай бұрын

Thanks for watching!

@amania9254 Жыл бұрын

Another informative video, thanks 😊

@PotterybyKent Жыл бұрын

Glad you enjoyed it!

@epidian6240 8 ай бұрын

Forma kiepska , zrobiona amatorsko musisz się jeszcze wiele nauczyć

@mikeh2351 7 ай бұрын

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 😂

@PotterybyKent 7 ай бұрын

Yep, just a demo for sure! But it is a great point that you can modify forms to suit your needs like that.

@erindemastes 9 ай бұрын

Cool thanks !!

@PotterybyKent 9 ай бұрын

No problem!

@dargon2001 5 ай бұрын

Muito obrigado pela aula sua voz é calma facilita entender e é muito bela também

@PotterybyKent 5 ай бұрын

Thanks for watching!

@hanelyp1 11 ай бұрын

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.

@PotterybyKent 11 ай бұрын

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!

@alans1816 Жыл бұрын

Thanks for a good series of videos introducing mold making. I've been on a similar path, and have some comments. While it's best to avoid bubbles, you can fix them. Make sure the cured plaster is wet, then fill. Wiping before cure or sanding after gives a good surface. When I started, I had problems with mold release. Let it dry before casting. After removing the model, while the plaster is still warm, thorough rinsing of the plaster removes the mold release agent. This speeds up subsequent slip casting, I think. (Not sure because I changed too many things at once, but it's easy.) Sealing with clay rather than glue won't resist buoyancy, but it's a lot easier to disconnect.

@PotterybyKent Жыл бұрын

Thanks for the comments! I tried fixing bubbles in the plaster at one point but had a really hard time getting access down inside the mold (my hands are not small!). As far as clay for sealing molds, I have also tried that but also managed to get a plaster disaster (not sure it was directly related to the clay though)! I have some ideas here that hopefully I'll get to try (and show) in the not too distant future.

@lumishamei6478 Жыл бұрын

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 🎉❤

@PotterybyKent Жыл бұрын

Thanks so much! I don't use a V60 myself but have seen a few. It would be a multipart mold for sure!

@mimamima-fr5yo Ай бұрын

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

@PotterybyKent Ай бұрын

It's 70 parts plaster to 30 water

@DanimalGrrrr 21 күн бұрын

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

@PotterybyKent 21 күн бұрын

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.

@dilian245 5 ай бұрын

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.

@PotterybyKent 5 ай бұрын

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.

@HealthyDiet-pk4kx 2 ай бұрын

Can we use white cement instead of Plaster? and how long do we keep liquid in the mold before pour out?

@PotterybyKent Ай бұрын

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.

@anjeolaemmanuel3107 Ай бұрын

Can you use a plastic bucket instead of wood ?

@PotterybyKent Ай бұрын

Yes!

@mimamima-fr5yo Ай бұрын

هل يمكنك ان تذكر المواد المستعملة مع ذكر مقادير الخلط

@PotterybyKent Ай бұрын

USG #1 Pottery plaster

@RoosterPootPottery 5 ай бұрын

What type of foam are you using

@PotterybyKent 5 ай бұрын

Here I used extruded polystyrene

@feminissue 5 ай бұрын

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?

@PotterybyKent 5 ай бұрын

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.

@caglakaplan1748 4 ай бұрын

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!

@PotterybyKent 4 ай бұрын

@@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.

@jeanmartin6410 20 күн бұрын

@@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.

@Detteermiig 2 ай бұрын

How much water do you mix with the clay to know that 30 minutes is sufficient drying?

@PotterybyKent 2 ай бұрын

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.

@Detteermiig 2 ай бұрын

Thanks for the quick and detailed response, makes sense :)

@Alexander_Estrada 7 ай бұрын

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): \ / / \ \ /

@PotterybyKent 7 ай бұрын

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.

@liejmarose 7 ай бұрын

can you do plates?

@PotterybyKent 7 ай бұрын

Yes. I haven't tried doing them myself yet, but have seen two part molded plates (cast solid).

@jeannetteelliott6951 8 ай бұрын

What if my object won’t release?! 😢

@PotterybyKent 8 ай бұрын

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.