49. Making a Pottery Plaster Slab for Recycling - wedging clay. Formula for Plaster & Water used .

the aim with this video is to explain to you um our process in making a plaster block so i can dry all my reclaimed clay um i hadn't done it before but i had used a plaster block at the pottery where i learnt and i'd used it as a wedging block as well to dry the clay out a little bit so first of all we've made a wooden structure but we found that it was a little bit unsquare so we're adding some um blocks onto that to make sure there's pressure down uh the reason i've used glass um in that on the bottom is actually because um i'd watched um simon leech do um one with glass and it had shown that it had released very well and very quickly and that of course could become the top and it would be flat so i contacted the guys at corby kilns in the uk to find out what plaster to use and it is actually a pottery plaster one that's also used for molds uh the one i'm using here is by a company called formula saint gabion and then what i did uh is i had a look and found a video um and actually they were using the same pottery plaster and i followed their formula but it is in a uk uh format and i had to convert it now what i did do though is um i have got that written up at the end of this video and another explanation of it so just to briefly recap here we've got a a unit that i want is 14 inches by 20 inches by two and a half inches deep you times them all together and you get 700 cubic inches you then use the 700 and divide it by 80 that gave me 8.75 quarts of water i then had to yes i converted the quartz into literature so i actually had 8.28 liters of water i then go back and use the 8.75 and times it by 3 to give me pounds of plaster so i use 26.25 pounds of plaster so to recap here i've got 26.25 pounds of plaster to 8.28 liters of water and as you can see i've got this very creamy consistency so the next part then is to pour it in we've just put it on a bit of plastic and we're pouring in quite gently um but it's not coming out the sides it's not leaking out of the side so we can just get on with it really the next thing we have and are going to do and you'll see that in the video is that we have a sheet of wire mesh that we want to put in the middle of the unit to try and make sure that it has some added strength this has been suggested by every one that we've watched um so that is what we are going to add in a minute now i thought i'm worried i'm good enough i don't know i love enough i think that's enough to put this into you okay that's enough to put this in your finger and have a feel before you do it yeah which way you're gonna go you hold you hold the two you you hold this frame i'm not gonna i'm not gonna take the frame off no you hold the frame it won't no it won't make it it's it okay it will still twist so just take one off yeah so i'm gonna take this one take that one off then i can get in brilliant okay that's it put that back on and then carry on camera's here i think you could probably start pouring it from the main unit now that's coming up though isn't it is it it's rising with you i think it is is rising up so if i put the camera back here let's put this down a bit just don't don't put it down so it touches the bottom i can put my fingers through all of it and it's fine it's not down to the bottom yeah deep is not gonna be a problem to you no no no no depth isn't a problem so we wanted to make sure that the what would be the bottom would be flat and uh i just came up with the idea of using this because this has got a rubber end on the edge on it and it worked very well actually and you'll see later on that when it's gone off all i did was actually scrape it flat with a pottery um tool um a trimming tool and it worked really well um i go over here lightly with the heat gun because i'm sure if any of you've watched any acrylic work or anything like that any bubbles or whatever and it seemed to help flatten it out but i don't know if it worked or did anything was really just to see if i could get the plaster to flatten but i don't know if it makes okay so this has been about three hours it apparently i've been reading on this if you have warm water to the water when you're mixing it you get more time to work it but it actually says six minutes um six minutes in the thing but this has been three hours now so i'm just going to take the side off and see [Music] what we have yeah that's just spring off there so it's actually sprung off i don't need to actually take that off because it's what i just said on the thing i just read about cutting the corners with a knife so you don't have these sharp corners while it's still soft and actually the best way to tell this this is still when it um was working it was hot because it's a chemical reaction and that chemical reaction now is gone and that is actually cold but you can tell that it's still a bit pliable so let me get something that we can use to just take these edges off off with yeah so i didn't really want to leave it any more than this i've followed um the format that i followed there part that was simon leech and simon leach said in the video that i just watched make sure you build the edges because you do not want to um hurt your hand this is going to be upside down remember the glass side is this side up it looks like we can already turn it over uh it's pretty good isn't it the the plaster is still you can feel that it's still soft enough to work at the moment this plaster this is the the pottery plaster it said if you're going to put your hand in it and do a hand mold it'll go off in a minute i think that might be worth a go don't you so i've gone for two and a half inches deep 14 by 20. i think i know that i shall speak through the video because i haven't spoken through the video we were having windows taken out today and so we have this window but the interesting thing is i'll just push this and it's already loose off of the glass so that is a really interesting tip oh all right let me turn that off and i'll go and grab the husband to see what the plan is i realize the only way that i'm going to get these edges off of here i can't it won't cannot be turned it cannot be lifted because it will just break so i'm just going to pull that off the edge [Music] oh [Laughter] there you go just wait for it to go off to tomorrow now or go hard hard i don't think he'll i suppose what you've got to do is just wait for it to dry and lose all this moisture now so there we go okay so here's a recap on how i mix the plaster this is following uh another video that's online and it worked well for me so it's 14 by 20 by 2.5 inches which all times together is 700 cubic inches i then divided that by 880 that gives me a weight in quarts of water now this is an americanism i presume we we don't use quartz in the uk but i then have converted a quart into a liter so that i can work that way it meant i had to use 8.28 liters of water and then going back to the original thing was this 700 divided by 80 actually gives you the amount of pounds in plaster so 700 divided by 80 was 8.75 pounds of plaster and to get the actual amount of pounds in plaster you can see that i've done the 8.75 times 3 that gives me the pounds in plaster so there we go the 700 by 80 is 8.75 quarts made that into liters that's the liquid base but the 8.75 is times by 3 to give me the pounds of plaster and in that case it's 26.25 pounds of plaster so just to show at an end uh the plaster it is up now it is up i've put my first i've got my recycling clay here i do a big big bucket and um i've turned it over once actually to see how it's working and it sort of gives you you can see the finish underneath is smooth i've got the smooth side up this underneath is now soft so so thanks everybody for watching and i hope this helps all these home potters work out whether they want to make themselves a plaster slab cheers

Channel: Lois Hook Pottery

Views: 1,203

Rating: 5 out of 5

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Id: VZ9kps0GlhY

Length: 13min 48sec (828 seconds)

Published: Sat May 15 2021