Part 1: How to Make a Two-Piece Plaster Mold for Slip Casting
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- How to make a two-piece plaster mold for slip casting. Part one, preparing the clay bed for casting. Watch part two to learn how to properly mix and pour the plaster.
For Part Two: How to Measure, Mix and Pour Plaster, visit • Part 2: How to make a ...
Special thanks to my former MFA professor, Mark Burns, who taught me nearly everything I know about plaster molds and mold-making.
Omg, your video demonstration is the best I’ve seen so far. You’ve provided so much knowledge and easy step by step instructions, giving me the confidence to begin on my journey. Thank you so much!
Glad to hear it was helpful! Thanks for letting me know!
Absolute BEST video series I've ever seen on mold making. I learned in my own. Very little help. If TH-cam were available back in the 70s...well, here we are! You are amazing!
Awesome! Thanks so much for the high praise! Glad you found it informative! I too love how much you can learn on TH-cam. What a great invention!
Nice thank you 💙
You're welcome 😊
So where did you get the bird from .....?? What if i want something that i don't 3:56 have a sample from .... can I create a sample to make this molds ??
I made the hummingbird out of clay, let it dry to leather hard, then I made a mold of it. If there is something I want to make multiples of, I make the piece out of clay first, let it get leather hard, then make a mold of it. Otherwise it would take me forever to make 25 hummingbirds by hand. After I slip cast them, I can assemble them in a variety of ways to make each one look different.
Awsome video!
Im planning to make a mold for some dice (6,8,10,12 and 20 sided), and wanted to ask from your experience
Would it be possible to make it with dice that is not clay you think?
What is the clay you use to make the mold? Would any type do or should i aim for a specific one?
Thank you!
Really great video, thank you for the clear explanation, awesome! You mentioned making a mold from bisque ware , I have a bisque piece I'd like to make a one piece plaster mold from, but I'm not sure what would be the best release agent for it if I wanted to make a mold, then glaze and use it later if possible? Thank you!
I would only use Murphy Oil Soap. It is a fantastic release agent. I would apply three coats of the oil soap.
Please do you know how to make this lion sculpture?
Not sure since there is no picture.
Very informative. Was wondering , what type of clay do you use for the bed?
I just use the same clay body that I use to make my work out of; nothing special. Sometimes in my studio I use a couple different low-fire clay bodies (whiteware and earthenware) and I just grab whatever is the most convenient.
After I am done using that clay for the mold, I then place it in separate bucket that I keep separate and far away from my usual clay. You never want to use this "plaster contaminated clay" again to make an actual piece that you intend to fire as it is too difficult to remove the plaster from the clay. If plaster gets into a piece that you intend to fire, the plaster will not shrink and therefore your clay that is touching the plaster will shrink and crack off (usually after the bisque fire, sometimes after the glaze fire). I've seen this too many times.
I then reuse this "plaster contaminated clay" over and over to prepare the bed for more plaster molds. As a result, what was once whiteware and earthenware end up getting mixed together and become different color. This makes it easier to differentiate your "mold clay" from the clay piece you are making a mold from.
So, it really doesn't matter what you use to create a clay bed. You just don't want to use an oil-based clay body.
You are amazing! So thorough and detailed. THANK YOU!!!!
Awww, shucks! Thanks for the nice compliment! Glad you found it helpful!
Thank you so clear and useful!
What is the clay/plaster equivalent of Pam spray if I’m planning on making molds for large, thin, flat pieces and i want to minimize the risk of my original clay models breaking when I take them out of the plaster ?
I don't know about using Pam instead of Murphy Oil Soap. It might work. I'd test it first. The key is that is must be water soluble and not a petroleum product. Let me know how it works!
AMAZING tutorial. Thank you so much for sharing your process. You could easily teach a master class.
You are so welcome! That is so nice to hear!
Hello Rebekah, absolutely great video! Would like to ask, did you use ceramic clay as your clay bed? Thank you in advance!
Yes. I always use a clay bed.
I agree with others here, this is an excellent tutorial! Thank you. The same applies for part two, and the video on using the mold once it's made. Really helpful.
Super! I'm glad you found it so helpful! Thanks for sharing!
Wow. You are highly skilled. Thank you for helping us.
Thank you for the compliment! It is my pleasure to assist!
Enjoyed the video very much, it was very informative. I'm dealing with a problem with getting my casting slip stuck in the plaster mold. It seems when my casted slip started to shrink in the mold, if I wait too long it shrinks too much and it part gets trapped in the mold, if I don't wait long enough it hasn't released yet and is too soft. I noticed your bird wings are a similar condition to my design. How long do you usually wait when you pour the slip and how long do you wait before you de-mold the parts?
Yep; I've encountered this same problem a number of times. Some of my molds cast and release very easily and some are more tricky. This mold is not particularly tricky.
For this mold, I usually keep the slip in for about 20 minutes, then pour out the excess. And then I can open it up after about 3-6 hours. Sometimes I cast them at the end of the day, and need to leave my studio for the day. In that case, I keep the mold upside down and then open it up in the morning. Keeping it up-side-down prevents the clay piece from drying too much as moisture cannot easily escape since the sprue is closed off by the table.
For tricky molds like you mentioned, the easiest way to release them is to use compressed air. Not sure if you have an air compressor, but if you blow compressed air into the mold (focusing between the plaster and the clay wall), it pops them right out, releasing them easily before they get too stuck.
If I do not have easy access to an air compressor, I open the mold, and if the clay is still very tender, I wait for it to firm up a bit more (15 min?) and then I pound on the mold with my fist (hitting the mold with the palm of my fist). I keep the mold right-side-up while doing this. Meaning, the mold is holding the clay piece like a plate holds food. This action of pounding down on the mold creates an equal upward reaction and the clay piece bounces out after a few pounds. But compressed air is so much easier.
I'll do a video on this.
@@rebekahbogard3322 Thanks! Your advice definitely helped, covering my mold and waiting longer to open helped the piece release easily
What kind of clay is best to use for making the clay bed please? thanks!
It doesn't particularly matter, just as long as it is not an oil-based clay if you are making a slip-casting mold. I personally prefer to use a clay body with no grog (because the grog rises to the surface when you sponge it down). But that is not that big of a deal. Just use whatever clay body you have on hand.
@@rebekahbogard3322 Thank you!!!
This is so helpful, thank you so much!
You're so welcome!