How to make a plaster slab for wedging and recycling clay (easy)
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- čas přidán 11. 02. 2021
- #plaster #pottery #wedge
Hey potters; A few episodes ago I taught you how to recycle your clay be using absorbent material such as plaster. After this many of you asked if I had a video of how to make a plaster slab like the one i showed in the video. This video will teach you the easiest was i know to make a plaster slab for your clay wedging, drying, and recycling.
IF YOU NEED TO KNOW HOW TO RECYCLE CLAY, WATCH THIS FIRST.
- • How to recycle your cl...
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You CANNOT just use the same constants if you want to go metric. I've gone through the numbers and found out why:
When you divide the volume of your container with 80 you're actually BOTH converting from in3 to qt AND finding the amount of water needed:
456 in3 * 0.017316 qt/in3 * 0.72 = 5.7 qt
0.72 is the amount of water needed per amount of volume of your container.
0.017316 converts from US in3 to qt.
So how did they land on the number 80? Try doing the calculation above without including the volume of your container:
0.017316 qt/in3 * 0.72 = 0.01249 ~ 0.0125 = 1/80
and
1/80 * 456 = 456/80
When using the metric system you should (I've derived these constants from the ones used in the video):
Divide your volume by 1.386 OR multiply by 0.72 instead of dividing by 80.
Multiply by 1.439 instead of 3 to get the amount of plaster.
Remember to convert between cm3 and L: 1000cm3 = 1L
ETA: Thank you for this great video!
In metric the ratio is super easy, because a liter (or cubic decimeter) of water equals a kilogram of mass, a milliliter (or cubic centimeter) is a gram.
...well and a cubic meter is a ton ofc, but i doubt there's any reason for a plaster mold that size
Normally you'd just go with 7 Parts of water per 10 Parts of plaster (by weight)
slight variations are usualy no concern
Thank God for those of us that actually pay attention to math 🤓Kudos fellow mathling
Because of a happy accident, I have been using canvas to dry my recycled clay.
Recently I could not longer use my plater batt for drying my recycled clay (evidently used the wrong plaster); so I had to find another way to dry the clay I am recycling. I had a scrap piece of canvas laying around and found that it works well. I just lay a piece of canvas over something to allow air under it then pour the clay into it. The air evaporates the water that makes it though the canvas.
There are lots of advantages of using canvas:
1) It is really cheap
2) It is easy to store (just roll it up)
3) It doesn't crack or chip or shed material
4) It scales up easily - you can use as many as you have space for
5) You can use the same piece with different clay types and not get contamination. To clean it, all you do is wash the canvas in a bucket.
6) It is super easy to move and work with. 1) To turn the clay, I put another piece on top and flip. To move it to my table to wedge, I grab the edges, flip it onto the table then peel the canvas off.
What is the material you use under the canvas to allow air to circulate?
@@CookbooksonRepeat Nothing, just the finished wood of the cart or sometimes I have it on top of my old plaster batt.
Do you use the kind of canvas cloths for painting? Or which kind? I like your idea it's more beginner friendly!
@@raniachairya I bought a yard of Duck Canvas at a local fabric/craft store (Joanns)
@@connecticutaggie alrighty, thank you!!
Thanks for the shout out guys 😁👍
Came for the info, stayed for the vibes. Thanks for putting this out into the world for newbs like me 😊
I use a large plastic dishwashing pan with a flat, smooth, unmarked bottom (this will be the side of the bat I will use). I poured water to a line inside the pan for the thickness, pour the water in a bucket, then add potter's plaster until the islands form, stir it thoroughly and pour the slurry into the dishpan. I don't do any other measurements. I can pop out the plaster bat onto a square metal pizza pan (it's a flat surface with tiny holes for air circulation that don't make marks in the soft plaster like a grate or grill can) in about two hours. It takes about a week to dry completely in a warm room. I do this with plastic bowls and containers of various sized to make hump molds, too. If you want to use both sides of the plaster bat, you can simply spray the top of the slurry in the pan with isopropyl alcohol to pop any bubbles on the surface and simply leave the plaster in the mold until it is very hard and dry to the touch, so this surface won't be as likely to chip, dent, or be scratched when you pop it out of the mold. You'll have a bat that you can flip over and use the other side once in a while, which is handy if you use different types or colors of clay and want to avoid cross-contamination or staining of a light clay with color.
Don’t forget to wear a respirator, plaster dust, like clay dust is not good for your lungs.
Love this video, it was a great example of what is normal when just starting with clay.❤
Great video! I just made my second plaster slab using this method.
Yes, visual instructions! Now I can make my wedging surface! You two are awesome!
wow... honestly this is going to be so much easier. I'm gonna go make myself a plaster slab this weekend!
I followed these directions and it was easy peasy! YAY! Thank you so much.
this was so helpful! I also wanted to step up to something bigger but was daunted by all the construction other videos and instruction went through for a box.
This tutorial is exactly what I was needing! Loving the podcast too!
🥰 i just made my own for reclaiming claim and a damp box following your instructions. thanks for making it easy to learn and understand.
Thank you for this super easy to follow video. I have used it multiple times over the last 18 months to make wedging slabs, and am about to use it again to make a damp box. :)
Smooth the moon crater surface off with a scotch brute green scrubbier within the first couple of days . Smooth and easy
Thanks for this reminder! I just made up a plaster slab!! :D
Thank you! I will definitely use this method.✅
Great video! It was super helpful.
Thanks for this in Detail information, I made my own and it workt out just all right.🙏
Finally a vid that tells me how to calculate how much plaster I'll need to make a bat. Awesome, thanks for super-helpful information !!
I've seen the wet box method and it never occurred to me to make a plaster bat like that, thank you for the easy instructions, another tip if you want to wedge and have like a plastic table is to use a small mdf board that you can rest against a wall
Excellent! I'm a ceramics teacher and wondering how to do a cheaper way to recycle wet clay. This is perfect! Thank you so much.
Love this! Was just thinking about this
I legit just bought plaster to make myself a wedging table and, lo, the teacher has blessed me with instructions 😭 Thank you!
i used those metal tray things from the dollar store that you cook in! it’s so easy and only takes a day to cure.
Love it! Thank you so much guys
This was soooo helpful. Wish I had watched it before I made three huge drying slabs out of regular plaster.
Also, I'll do my own research but, metric system conversions would be nice.
do ya own research.
I found out why you use plaster for ceramics instead of regular plaster. The builder's plaster becomes brittle and as you use it to dry clay, a film of it actually strips off and is incorporated into you clay. Not good! It absolutely ruins the clay. Makes bits just pop out of your pot days to even months after firing. Thanks for reminding us to use the right stuff!
So I made a plaster batt a couple of years ago from plaster from HomeDepot and I have never liked the batt because I keep getting plaster in my clay - now I know why. It also has gotten a gouge in it, and has cracked - even though it is in a reinforced wooden frame.
@@connecticutaggie that sux. Yeah I noticed when I used it (home depot plaster) that it did the same thing. Thankfully I didn’t ruin any pieces I had made just a bunch of clay. 🤦🏽♀️ Only then did I find this video. Better late then never I guess. 🤷🏽♀️
yup I learned this the hard way! Rather than throw out the plaster slabs I had made for clay recycling, I just lay tea towels over the plaster and dry the clay on those. It still dries the clay nicely without it having any contact with the plaster. I then wedge it on cement board. Eventually I will try again, use the right plaster and follow this video!
This video was/is FANTASTIC! I just made two plaster slabs; both from IRIS containers. One container is labeled a "41.2 Qt" container with dimensions of 23.625" x 17.75" and the other was labeled a "46.6 qt" container (it was taller) with dimensions of 15.75" x 19.69". The plaster set in less than 30 minutes and I was able to pop the slabs out the next morning! I love the size of the bigger one, but it is heavy. I also noticed that the thickness of the slab was 2.75" rather than the 2" I had targeted. I suspect it was because the sides of the containers were sloped outward toward the top of the container and were probably the dimensions that IRIS reported. I'm doing a new set at a reduced mixture (0.73) to see if I can hit that 2" thick mark on the nose. Thanks again, for the video. It has made my day/week/month/year!
terrific video - thank you very much
I totally did this. It's currently setting up.
At most home improvement stores you could also purchase a concrete mixer pan they come in 2 sizes, curved corners. After watching you video that's what I will use, but also looking at end product yours kind of has handles. Thanks
This is fantastic, thanks! Gloves are generally recommended as plaster is hard on skin.
Lindsey The Monster Dillon is great in this video. Have her on more often Dante!
Thank you both for the info
Thank you both!
Lol Lindsay has got my sense of humor, seems lik a super cool chick to hang with..thanks for the video!!
I know this was a year ago. A trick to pop the bubbles. Us a small hand torch on low and just wave across and the bubbles will pop. Learned this tip from making epoxy resin art.
Great video. I did this to make a wet box for things like handles and knobs that I make in advance and keep moist for later. The lidded tub allows me to keep the plaster he moisture of the clay I'm using, and my handles will stay usable for a long time. Take off the lid though, and it sucks the moisture right out of them in minutes! Of course it does! I'll be making drying slabs this way for sure!
Is the drying box just a lidded box with plaster in the bottom? Interested in making a few.
Love this!!!!
We use round rubber feed pans from tractor supply to put the plaster in. They work great.
Thanks for the video. To anyone trying it my tip is chose the place to start carefully, don’t try to move until it’s completely dry. I think mine is cracked down middle as I made in kitchen before moving to studio. I wanted to avoid plaster in clay, as that’s a disaster
Nice! Thanks!!
First of all... this made my day, so thank you! You might find that it wouldn't slip or shift on a table if you use that rubbery shelf liner stuff. I use it a lot in my workshop for various nonsense.
They make good cheapo batt mates too.
Thank you Lindsey and Dante's hands.
Dante's special pottery and video making talking hands
Another great video. Thank you. I saw a video on making a wet box that was very similar. If you leave the slab in the box it is basically a wet box? Very cool. Thank you.
Ive made a wet box with plaster and rubber made tote I did it all messed up still works alright tho I want to make a plaster slab right now thanks donte and Lindsey
I’ve seen this also do double duty as a damp box too!
Making my plaster slaps to day thanks
Thanks for doing this! I
You always seem to time your videos on point to what I'm planning to do in the next couple weeks. I just bought a 50lb bag of plaster. LOL
I was planning to pick my bag up tomorrow. I had complicated plans involving garbage bags and boxes. This is so much easier! A new cat litter pan might work well also...hmmm...
Just spray the container with Cooking spray and it releases with no need to hit with a hammer👍
Hey there thank you for the great video ! I have followed the instructions and bought pottery plaster to make one on my own. The problem is it has been 2 weeks now and it does not dry and it is a bit too soft in terms of it didn‘t harden well. I am pretty sure a i mixed it like it is supposed to be mixed 1 kg plaster with 0,7l water. I don‘t know what went wrong. Maybe you would know what could be the reason of it not drying?
Got it Wants! 🤗
More plaster per water makes a less moister-wicking plaster slab. Recycling clay needs a slab made from a ratio of 2 3/4 lb. plaster to 1 quart cool to room temperature water ( don’t use hot water). Also it is necessary to have good air flow around slab when drying for increased strength.
Thank you so much🙆♀️🙆♀️
Do you have a source for that correction or is that just off the dome? This would be good to know if it's true.
Question--I have a plaster bat but the bottom is all pocked marked and uneven. Can I pour a new layer of plaster on top of it so it will be smooth again? Will the new layer bond to the plaster below it? Thanks for all your great videos!!
Thanks for sharing this video! I did this yesterday and it came right out of the mold! It IS beautiful! I used alcohol spray but it really didn’t help all that much. 😅
Do I have to wait before it can be used?
Thankyou!!
Thanks for sharing your tips. Pottery plaster is not available in my country (Malta). Can I use plaster of Paris instead please? Much appreciated.
Yes, you’re right, I needed this information!
I'm new to pottery, started using a colander(For ventilating the underside) lined with an old bed sheet, putting the slip on top of the lining, and then putting another bed sheet on top of the slip. Seemed to work pretty well and didn't need to flip the clay. ¯\_(ツ)_/¯
Nice thing about this is you can pop it back in for a damp cabinet!
Hi, new Potter here. Which of the two sides should I use? The smooth one or the side of the moon one? Does it matter?
do u think it would be possible to use this method + coating with a sealant to create a table(coffee table)? will it be durable? tia.
I noticed that in the video, Lindsey talks about scraping the rough surface off of the slab. Is it possible, instead, to just flip the slab over and use the smooth side for recycling/ wedging/ etc?
I was thinking the same thing!
Hello! I have left my slab for 5-10 days in the box and whilst it popped out easily there seems to be a bit of moisture left in the plaster - i.e. i can dig my nail into it very slightly. It doesnt feel dry and crumbly, but softer. Does this mean it's not quite dry yet? I used pottery plaster. Any info would be appreciated! :) Thank you!
How thin can it be? Wondering if it would crack if I made it 1" or 1.5". Thanks!
If you smear a very light coat of vegetable or olive oil with a paper towel it works wonders
I’ve used plaster of Paris from Home Depot with the same method and it worked well
i cant find plottery plaster in my country
i was wondering if i could use plaster of paris but does it come off and get mixed in the clay?
@@syedhamzahaider512 yes it does. It will ruin your pieces when firing. 😐
@@emilymccarthy1 so should i use a Cement block?
@@syedhamzahaider512 I am no mean a expert. Lol. I think I’ll leave that for someone with more experience. 😊 I just have had a bunch of people inform me of the plaster of paris. Plus I noticed it was leaving a slight white residue when I wiped it with a sponge. So I knew it was doing the same with my clay 😐. Hopefully someone will have a answer for you soon. ✌🏽❤️
@@emilymccarthy1 lol okay 🙂
Have a nice day 🤝
Could you set a mold (like a plate) into this type of ratio for slip casting?
Was Lindsey flicking everyone off during math jam
Can confirm, intro footage is dope.
Do you find you need multiple slabs for recycling light and dark clay? Or can you use the same slab (obviously not at the same time!) without too much cross contamination?
cool vid. Did you use a mold release, or does it just pop out?
Is there an easy way to make a small vertical rim along the edge of the slab? Like maybe adding a piece of plywood just slightly smaller than the size of the container to make an indention in the main part of the slab?
Does Perfect Plaster work as well?
Found a conversion, 5.7 quarts of water is 11.89 pounds. I wanted to be able to just weigh everything out since I don't have a large pitcher with units of volume
5-gallon buckets are handy in moments like this, especially if they're semi-transparent and have graduated measurements on the outside.
Try a palm sander or something that doesn't vibrate too violently against sides and underneath to release any air bubbles.
Is it necessary to smooth down the rough side of the slab? Is that the side you will use to recycle the clay? Could you use the smooth side? On the upper rough side of the mold you mention a alcohol spray. What is the recipe for the spray? Also, do you think you could used a hand sander to knock off the rough parts?
You can if you like ( make sure to give it a few weeks to dry completely) but I use the rough side as a grip for the ground and just use the smooth side. It works well when I wedge on the floor .
Can I use plaster of Paris? Is that the same thing as pottery plaster?
USG #1
Video on making a plaster of Paris wedging table….?
I understand why not to use regular plaster and stuff but would it matter if I put a moist cotton cloth in between the plaster and clay? I prefer to use a cloth sheet in between bc it’s just easier to flip the clay or carry it out in one piece and all that, but do u happen to know if it’ll keep the regular plaster residue and pieces from getting onto my clay?? Idk if you’ll know this tho.
that's what I do in my damp box and what I made for recycling clay (I agree that does make it easier to flip it) you just can't wedge on the regular plaster and it won't be as durable so you can't move it around the studio much without it being in a box or frame already.
Is casting plaster the same as pottery plaster?
Great tutorial! Question: I’ve been pretty paranoid about having plaster around my clay room due to cross contamination, keeping everything separate, even mixing up outside, different buckets, etc. Am I going overboard? Thanks, Brian’s wife
Most of us buy plaster in a dried form and we mix it with water in the fashion I showed in the video and use it immediately.
You should not be keeping plaster in a wet state in a bucket to the point where it gets mixed with other things.
Buy the plaster, use it, keep it dried form in the original bag you bought it in. This way it is still separate and labeled while you can still make your blaster mold
I made this about two weeks ago and there's no way for me to release the slab from the mould haha I've tried hitting it with a hammer every day for the past week and nothing. Any tips?
i cant find pottery plaster in my country
its ther any alternative material to thing i can use instead???
Concrete and wood work pretty well. Before I started using plaster I would often just get smooth bored from a supply shop or from a hardwood store and use that.
Remember you just need an absorbent strong material
Are there any updates about the plaster availability? Looks like Amaco no longer makes the product. Most stores I’ve found run $100 for 50lbs.
Would cement board work to recycle clay on??
Yeah but nowhere near as well.
I have done this but did not make it thick enough the first time what I found works best for a smooth surface is the bottom side that was against the plastic container
Fo sho. I usually flip mine over to a smurther surface.
@@EarthNationCeramics also, I've found it more effective if the plaster has airflow underneath. I.E. mine is on a metal shelf with slats.
I have a large deep stainless steel tray. Will the plaster pop out of this mold or must I use a plastic container?
yeah it just wouldnt be as deep. i aim for 2" deep
@@EarthNationCeramics Thanks! I've done the math for larger and deeper as it is a very large form. It will sit upside in the tray on stilts for air circulation. I've been planning for months LOL.
Where do you buy pottery plaster?
What's the difference between normal plaster and pottery plaster?
What size is your plastic container?
The IKEA tote..or any tote... is the form for the slab...
Is potters plaster different then plaster of paris?
Thanks 400 gr =1 lb!
Notes to self..
Is that bin really only 12x19 inches? It looks way bigger.
actually if you add too much plaster you can "kill" some of the plaster absorption.
Remember it needs to absorbs the water from the clay, so maybe if someone thinks it's a good idea change the number to 5 or higher, maybe isn't a good idea.
I’m asking this before watching the whole video (I will, I promise), so sorry if you cover it. Could this be used in a damp box as well? Like could I have a dual purpose plaster slab? I work in a communal studio with limited space. Thank you and I’m watching the rest of the video now. Promise.
Yes but in my experience that has a habit of growing mold
I tried this but the plaster is taking more than 5 days to dry!! ( I am at day 6 and it’s still damp to touch) I had to pour some water off the surface since it’s just pooling there. Any clue why??
Sorry if this is a silly question, but does the x80 formula still apply to metric units of measurement? I am from Australia and i can't find metric ratios anywhere for making a bat like this one.
Yes. We potters generally do not use the imperial system. We use grams. Metric is more accurate for us .
Imperial Is such a bad system Even our drug dealers switched over to grams.
I am from Australia too but I ended up converting to imperial just to make sure I got it right.