Це відео не доступне.
Перепрошуємо.
Slip Casting: Back to Basics
Вставка
- Опубліковано 10 чер 2022
- In this video I cover the basics of my slip casting process. I take my mixed up slip and pour it into my plaster molds. (See my other videos on how I make my slip and my molds). The slip sits for a while and the plaster absorbs the water from the slip. In the process of doing so a pot is formed against the plaster. Once the wall thickness is large enough, the rest of the slip is poured out. The pot and mold then sit for a while longer. At this point the plaster continues to draw water out of the clay and the pot firms up. Once enough water is absorbed, the pot releases from the plaster and it can be pulled out. At this point it is just like any other pot! You can let it dry to leather hard and trim it. Once it is bone dry you and bisque, glaze and then do the glaze firing!
They look great, loving the new molds so clean and simple. ❤
Thanks so much! 😊
Yeah, you're back! Missed ya!
Thanks!
Happy to see you back again!
Thanks! It's nice to be back.
Im confused. I keep hearing people mention "slip" but what is slip? How do you make it? And can the same be accomplished with cement? I've been using fast set all crete for my projects and have attempted "slips" many times but it cures too quickly and becomes clay like even after 5 minutes. So there is no pouring out the excess
Slip is specially formulated liquid clay used for ceramics and is fired in a kiln once dry like other ceramics. It is a very different material than concrete.
I have a sculpture that’s ceramic clay (not bisque) I’m worried that if I try to create a plaster mold, the sculpture will shrink and warp, any suggestions?
You mean it's unfired ceramic clay? I know people do make plaster molds that way - the plaster sets pretty quick so I don't think deformation is a huge issue. However I'm pretty sure the original is lost in the process and I've never tried myself.
@@PotterybyKent thank you!
Do you have a recommendation on what slip you use? Also what ratio you like to use if you mix? I have molds, but still learning what to do with mixing slip. Thank you in advanced.
I also think a video about the slip itself would be beneficial(different ways to make slip vs. What to buy at the store).
For a beginner I'd suggest buying pre-made casting slip. You don't need anything else! Several professionals use that as well (eg Laguna).
I actually use dry clay formulated for slip casting from my local pottery supply shop (so unless you're in Silicon Valley, that's unlikely to be very useful). For that, I use 70% clay and 30% water by weight in my slip and then some Darvan 7 for deflocculant. Darvan is very tolerant for amount used (whereas others can be much more touchy and I avoid). Put the dry on the wet, mix it, let it sit and slake, mix again. Etc. At least 24 hours, more if you have time.
That's all there is to it really! I think there are more advanced processes you can use, but this has worked well for me.
Do cover this is some of my other videos but it's a bit scattered here and there (including reclaiming the dried clay, etc).
Oh wow! What an amazing reply. Thank you so much for being so detailed ❤️ I will see what I can find here. I might have to go Amazon since I'm 70 miles to the next major town here in Idaho lol. Thanks again!
@@Autumnh141983 Happy to help. Many pottery suppliers will ship (and you'll know what you're getting that way!) but that does come at a cost.
Hi Kent, I have zero experience with anything clay related other than making trinkets with air drying clay. Do you think I'll be able to start my journey with clay from slip casting?
That is basically what I did! It's not the traditional route people take but it is possible for sure.
Great info! Thank you
Glad you enjoyed it!
So cool!
Thanks!
I'm assuming you can add masonry stain to slip. Just tossing around some ideas.
I'm not sure those would survive the firing process. The kiln gets HOT! Unless you mean Masons stains. And if so yes those do work
@@PotterybyKent I'll find out tomorrow. Thanks.
@@PotterybyKent You were right. What was originally a few shades of red are now shades of yellow/orange. Ran it up to 1030° C on fast firing. My test pieces got a little black halo in places which normally comes from pit firing.
But I got the answer I was looking for. I bet the dye in question was for concrete.
Personally I'm looking forward to colors for ceramic Calla lilies, real ceramic stains.
@@lamardon9723 Thanks for the update. I was confused about the name "mason stain" for awhile until I realized it was the name of the company who makes the ceramic colorants: www.masoncolor.com/ceramic-stains
Great vídeo, one question, how long would you say the slip stayed inside the molds before drainage?
Mine usually sit for about 20-30 minutes. But that answer likely isn't very useful. You really need to just test it out with your own molds since they all absorb water differently. Any one mold will also change depending on how recently it's been used.
Hi Kent, thank you for such a great video! Video, I oved the fact hat it's short uet educative!
Sorry for the dilettante question. I want to tray making candles with dlip cast vessels. Do I need to ovenproof the slip cast vessel prior pouring wax into it & burning a candle? Thanks in advance.
Thanks! I have made a few candles before and use my regular fired pieces for them.
OK, Thank you so much for your reply@@PotterybyKent
Do you have to wait to use the mold again once you remove the cast? Or can you just start the next one?
Best practice is to wait. However I have successfully cast back to back on several occasions. The plaster is absorbing water from the slip, so the second time around it is already damp. That means it'll absorb water less quickly so the clay walls will build up slower. If you're not super worried about 100% consistent wall thickness (eg not for production work) then it isn't a huge deal. It might also make demolding a bit tricker but for my forms it's been fine. If you do it enough, eventually the plaster will be saturated and it'll stop working. I think the most I've done in one mold in a day is around 3 casts. Warm/dry weather helps too since that'll help the water evaporate.
very nice details! Would you happen to have a Generic "zirconia slip" recipe that you can recommend? I'd like to slip cast some ceramic tubes for a muffle furnace and thought that this might be the way to go!
I'm afraid I don't. Right now I'm buying my slip in powdered form from my pottery shop.
Hi Kent just one question how long did you let a new mold for slip casting cure before using. Thank you for your answer.
I usually let it sit for a couple of days. It hardens very fast, but some of the moisture needs to evaporate to pull it out of the slip. (From what I understand a mold being too dry is also a thing on the flip side).
I was wondering if the mold that wasn't centered in the plaster gave you a pot that was even thickness all around or if one side was thicker than the other.
That is a good question. I try to get things centered when making the molds (but didn't quite manage for these). I'm pretty sure the answer is no it doesn't mater too much in practice (at least as long as there isn't a crazy difference).
One of the reasons to use plaster is that it is porous. Once the water is in the plaster it will move around some (it's not making a straight line exit). Likewise the plaster is losing water from all of the exterior sides. There might be areas that are locally more dry, and those could pull more water out of the slip, but they'd also pull water out of the adjacent plaster. So it should rapidly reach equilibrium.
I could imagine there might be some small effects, but at least for me, I haven't see that issue arise.
@@PotterybyKent That makes sense. Thanks
thanks for the video. I bought some casting clay a few years ago and didn't use it so now its thick. can I just add some water to it?
thanks
First try mixing it and see if the deflocculant in it does its thing and loosens it up. However if water has evaporated, then yes you could probably add some back in.
@@PotterybyKent On this and since this is such a new comment. I've bought some slip powder, mixed it to the manufacturer's ratio and with the reseller-suggested amount of deflocculant. I'm getting a thick pudding slip. Guessing specific gravity is the thing to keep constant and more defloc is generally better then?
I'm 3d printing molds, to cast plaster molds to do slip-casting, but it's all learning from scratch here :)
I got a good test mold working (sand it after print, coat in microcrystalline wax and use like that. Trying with soft soap as mold release always gave rough surfaces)
I also got decent slip castin results, just hard to work with it when the slip is hesitant to leave the mold :D
@@MBaadsgaard You want as little water as possible in general and that is what the deflocculant does. However it really depends on the deflocculant - Sodium silicate is very touchy and I don't use it for that reason. I only use darvan which is much more forgiving.
@@PotterybyKent Thanks for the answer, I'll try out higher deflocculant and see what I get. I'm using sodium dispex which is only problematic for how incredibly small quantities you need.
How long do you have to wait between casting in the same mold?
It really depends on the mold. So try it and see is really the best answer. I've cast in the same mold back to back when it's warmer and it is ok but I need to let the slip sit longer the second time. Basically the plaster becomes water logged. I think a lot of people will only cast once a day to get constant results (wall thickness) however even that depends on the ambient temperature/humidity of where the molds are.
Hi, Kent, thank you for a great and I formative video. So I was wondering when making your molds, how did you create the lip? You have mentioned that you 3D printed it, can you please share your process of how to make that lip? Or maybe some alternative ways to make it without 3D printer? Thanks!
Sure thing! I didn't film making this particular mold, but I used some 3D cad software to design that part and put it on my 3d printer. I did some basic measurements and extruded the round shape, etc. Depending on your skills that is either very easy or very hard!
If you don't know 3D modeling and printing, you can create it other ways. I've taken existing pots and molded them as is and just clean the rim afterwards. I've also done things like use foam or cardboard to get that shape. Here's an older video where I did just that: ua-cam.com/video/b4Q7bLmgIQc/v-deo.html
@@PotterybyKent thank you so much for quick response :) Now things are coming to pieces. I've watched your video and I am very surprised that there are such ways to make it! Of course it doesnt look easy :D but I might give a try when making my next mold :) thanks a lot for sharing with us your process!
How long is a while
Which one? If you're asking about how long the slip sits - it depends on your slip and molds. So you really need to test it and see if you get the mold thickness you want. Likewise for waiting for it to set and then demold. I usually give about 30 minutes for each.
'what clay do you use for your casting ?
I'm getting powdered cone 6 clay designed for slip casting. I just need to add water and my defloculant. In particular I'm using: shop.clay-planet.com/dry-icelia-porcelain.aspx
do you know if i can cast with regular clay ? even it has grog in it ?
That is how I started actually. You need to figure out the water content (I have a video on that) and the grog can settle out some. It also isn't as easy to work with as casting clay, but I did it that way for maybe a year when I started.