Tufa Casting

hello everybody my name is jonah hill i'm a hopi kwitsan silversmith woodworker printmaker from the village of kikutsmovie i'm a tobacco and rabbit clan and i'm here today to demonstrate the fine art of tufa casting so i have a few different chunks of tufa and depending on where you get it and how you mine it it can come as little blocks like that or depending on like i use a chainsaw to cut mine and i end up with as long as the bar is so you have big giant huge blocks which are really cool because if you want to make bracelets you really need to be aware of how long your piece is you know so an average bracelet would be about six inches depending on your wrist size you know male females really have different wrist sizes you know so but uh for bracelets see this is six inches right there and one thing about tufa casting is that you really need a lot of room from the top the button area here which is this part so from here to the start of your design you need some area for the metal to flow down into there if you have your design way up here chances are when you're pouring the metal the design will get washed out you know so you end up with having a really smooth surface transitioning into your design you know so you lose texture you lose design so you really have to think about what you're gonna make and um the steps to it so for something like this these are really good bracelet bars you know so there's enough room for your design plus enough room for the metal to flow in there and with tufa casting you're doing what's called a gravity pour so that means that once you're finished carving and you have your mold together like this once you put it up you're using gravity to help pull it down to the bottom of the mold you know so there's things to think about with that so um i guess right now what i'm going to do is just i guess example show you how to make a bracelet so i think for this demonstration i'm going to make one of the bracelets that i'm pretty much known for and i haven't really carved it in a while but um i do a bracelet called heron along the river so it's basically a hair in tracks walking along kind of like a wavy pattern with water swirls on there now what i'm doing is outlining the bracelet mold that i'm gonna make so this is gonna be about eight inches from the top to the bottom here and the bracelet's gonna be about six inches so what i'm doing now is making guidelines where i'm going to start taking away the material and now i'm going to measure it and kind of just so i don't have too much material or too much space i'll mark where six inches is okay so now that i know that i have this much space in order for the metal to flow down there before it's actually touching the design so from there what i'll do is basically you're just going to start degrading the stone and taking away material what's really cool about tufa casting is that since i'm a woodworker and a lot of my later works that i was doing before i stopped wood carving where my relief works you know so basically what tufa casting is is relief carving which is awesome because you're thinking about depth you know you're when you're doing a relief carving what i like to do is carve things really deep and then that way you're working with shadow you know so if you have your carving and you have a lot of really sharp angle sticking out you have your your design poking out of the wood you know it makes it more dramatic so with tufa casting it's basically that same process same um idea of it you want to kind of think ahead about how deep you want your piece to be how heavy you want your piece to be the depth of the design determines how much silver you're going to need i've done in the very beginning i've done pores where i thought i had enough silver poured the metal in there and it only came up to like right there you know so that's another piece that ended up getting turned into a pendant or something you know so like with everything you know all these artworks that you do is you just have to be confident if you can see this is really soft tufa and i've done carvings where i've just used my finger and that's degrading it see it's so super super soft you know so you're making a mark you know and even the pores on your skin you know your rough skin if you have it will leave a mark so i've done things before where at the end of my carving i've just taken my finger and did that and it leaves like these really cool scratches in there and you're thinking about texture as well so what's really cool about tufa stone is that the texture comes from the pores in the stone and the more porous the stone is the better the texture will show up so with this here what i'm doing is just basically degrading it and called making a channel so once you get your channel deep enough that'll determine how thick your bracelet is one good exercise if you're a tufa caster is to try to get a very very thin casting which is pretty hard you know so say you wanted to get like maybe a 22 24 gauge sheet this would be about that gauge right now and a trick to do that is is if you want to have a really really thin gauge of metal you would start thin down here and slowly degrade thicker here so that you have more of an area opening to pour the metal in see so you can kind of see it now where it's getting a little bit of a channel in there so if you're doing really thin pores this channel gets really deep but the channel down here stays thin so you have a lot of the silver is going to be pouring in there and slowly the gravity will suck it in there and you'll get a hopefully a pretty good pour you know the bracelet i'm wearing right here this is my second tufa casting before i actually understood the whole process of everything so there's a few different things as i'm going along i'll demonstrate but this was a miscast the design didn't come out here you can see a little bit of a divot here and here you can see where it's really thick here because my sprue led into my design so that was a pretty uh pretty i don't know to me it was a messed up cast you know and i really struggled to decide whether or not i was gonna melt this down and make something better you know but i figured you know it's like a almost a full bracelet it came out pretty cool so i decided to keep it and with your artwork you know a lot of your very first pieces you want to keep you know because that kind of reminds you of where you started at as to where you're at right now and that's what's really funny is because this even though it's a miscast it's one of the most uh when i go to shows people are like well where is that piece you know and it's kind of funny because it's like oh it was a miscast so right now what i'm doing is degrading the top part more so that we're getting kind of a step going down you know like a gradual ramp that's going to be thicker up here for the metal to easily pour into there before it starts getting to your design so right now i would say this is about an 18 gauge bracelet you know so we're gonna get it down to like maybe 16 or 14. um depending on the collector people either like their jewelry really really heavy or really really light you know i always joke around it's like the heavier the jewelry is it's like a sign of reliability you know you're not going to break it um so right now here's the channel so if you can kind of see it's got a good depth to it now what i'm going to do for the bracelet that i'm going to make i'm going to use this cottonwood tool that i make and with tufa casting you know any tool that will make a mark will work you know i use um wooden tools that i make i use dental picks uh round files are handy to make your sprue a paint brush is good to pull out the excess dust and it also exposes the pores more a ruler and that's about it you know i mean uh the simple tools you know so you can carry all of this around in the bag and not have to worry about it so what i'm gonna do right now is create a border for this bracelet so i'm just using this edge here and basically it's just a repetitive line that you're doing so i talked about depth you know so here is where i'm going to make it so that this edge here is going to have a little bit of a lip and that's the design is going to sit inside of there see so you're basically you're just degrading everything you're going over and over and over it's a lot of repetition um if you're doing this in a windy area you want to make sure you're wearing a face mask you know this is a nice protected area so i don't have to worry about dust flying everywhere you always want to think about safety when you're working with stuff so here is the beginning of the outline for this bracelet so that's adding depth to it it's going to be a nice solid border see we're doing a wave we're doing ripples they're just kind of making guidelines and then depending on what tool you're using will determine how your design is going to come out see so right now i'm carving in the water line you know and then i'm leaving room on this side for the heron tracks but like i said you know you're worrying about depth so you just kind of keep going over and over your mark there the deeper you go the more bold your design will be toofa is really cool because you can erase lines if you wanted to you know you just basically dig in more so right now there's a couple of deep divots that i did right there and now i'm going to erase those out and make this a little bit deeper here another line here and at the end hopefully this is going to be have kind of like stages you know it's going to have a little bit um really cool depth see so you just use pressure gentle pressure at first and then you can start digging in more just let the tool work for you you know you're just guiding everything you're being really gentle this is one of my favorite designs to make because so right now we've got the waves coming along the river's flowing you know you're seeing the water go um with things like this you know you want people to experience the piece you know right now i'm just going to use the pencil lid and start carving in little bird tracks here so a little heron walking along here so the carving part is just one aspect of this tufa casting see once you get all your carving done you still have to do a few more steps but you want to take your time you want to be gentle depending on the hardness of your stone you know this is a soft stone so if you're too rough you can um tear out your design basically and you end up with like a big giant wad of silver on your piece and that doesn't look too sexy at all so so to me now this is a really simple design you know it's basically done i can do the pouring but there's a few different steps that you have to do before that happens so right now i'm going to determine where my hallmark's going to be so which really cool trick is is all of this dust that you see here you can gather all of that up and basically sprinkle it in here so i'm going to do my lemayo c hallmark which is a whole word you know so i want to make sure that i have enough area on the piece and it's going to show up on my other part so just basically spread a bunch of dust in there flatten it out and what the dust is going to do is basically going to show you where this part of the design is on your backing here see so the backing is just another piece of tufa that's flattened out kind of determine where you want to put it at and then it's basically you're going to flip it over like that you can tap it two foot is very fragile so even like when you're mining it you know you can get a really big nice piece come out and take it home and cut it up and it'll fall apart you know so always be mindful of how you're treating your tufa and how much pressure you're applying to everything see so that tells me where i can carve into my design without having to like worry about it like skewing off or not being on the back side of the piece you know so now that i know where that is i'm gonna just make my hallmark so like i said everything's inverted so you start out with your last letter first then you go backwards so okay so you got your inverted hallmark and with this piece too i think i'm gonna add a little bit of other decorations you know so you can do uh like even more bird tracks if you want to you know so we got that okay so there's the backing there i'll put it together like that and then see it's still within there now the next stage is prepping your your final piece you know so you've got your carving you've got the channel that it's going to flow into you've got this part here the opening which is called the button sprue and then now one one thing that i didn't know when i was doing this piece here is that you need vents so what happens is that your mold is a hollow form inside of there right and that there's air trapped in there so when you have your piece ready to pour and if you don't have any vents sometimes you don't need a lot of vents you know but it helps when you pour your metal in there there's air trapped in there and the metal sometimes has a tendency to get cooled by the air that's trapped in there so that that's what happens when you have a miscast or it doesn't flow all the way to the bottom uh an example with this that little divot there i only had a vent here coming out an event here coming out and vents are basically just these little lines that um allow the trapped air to flow out of see so you want to make your vents from your edge of your design leading up at an angle so that when you pour the metal the metal doesn't go flowing out of the vents you know it's gravity is going to help stop it basically you're going to make a pretty deep line leading from your design all the way to the edge of the tufa um everybody does this a different way you know depending on who you're talking to who you're learning from um there's no correct way i guess you know there's like certain ways you can do things that will help your peace come to a a good pour but still you know it's like all just how you treat the stone it's about how intricate your design is um vents really help you know see so i'm making a whole bunch of them which is cool because you're just basically hedging your bets you know you're ensuring that the metal is going to flow down to the bottom and that the air is going to get sucked out through these vents so you're wanting to make all your little vents kind of leading up to the end here and these are just simple carvings you know depending on how intricate you want to get will determine how your vents go how much your carving is going to go see all the way to the top even though you're not worried about the this part having a design or anything you just want to go all the way to the top with your vents okay so basically this piece is ready to pour um i'm not seeing any kind of like real big design flaws or anything um the design looks pretty good here i'm just gonna carve this one in a little bit more just to kind of highlight it a little bit right now this one is ready to be poured so there is a few steps to the pouring process and we'll switch over to this little station here okay so right now um the method i use the materials i use are an oxy acetylene torch so it's a mixture of oxygen and acetylene which creates a really really hot fire this here is a crucible clay crucible that's treated with borax powder in the beginning to create a basically a non-stick surface inside of here so if you didn't treat the crucible and you melt it silver the clay with the silver would stick to the clay in here so what you do is you heat this up pour a bunch of borax in there and it forms a glass surface and that allows the metal to flow smoothly in there and the metal i'm using is just scrap silver here so so you have your crucible you have your metal in there i have my little station where the piece is going to be propped up what i use is an old recycled bike tire tube to hold the piece together some people use a clamp you know you can just hold it together using force but um i like the bike tubes because they you can feel it getting tight you know so we have all our pieces set up here we've got borax powder to help clear clean the metal as it's melting so first stage in doing the actual pour is you want to carburize your stone so carburizing means that you're applying carbon to the surface of the stone so non-ferrous metals can't stick to carbon you know so what you're doing basically is lubricating it it's like spraying pam on a pan you know so what the the carbon does is allows the metal to flow into the design but it's also making it so that the final piece like flops right out you know so you just want to get it so it's nice and black coated with carbon here so we've got the piece carburized here now you basically just want to get your backing and your front and line it up see we got our opening then you get your bike tube and you want your piece to be nice and tight together you know so basically you're just going to wrap this around there hold it together and then just go all the way around the top see i like the tube because i can feel it getting tight you know it's like it's really uh i've done it before where i clamp them together and at the last minute it slips you know with this rubber tube method it's like it's not going anywhere it's nice and tight in there see so you got your piece put together i'm going to put it in my little stand here okay now let me get my middle put this over here or it's not going to melt okay so safety wise you want a nice fire retardant glove which i used to hold the torch you want to use eye protection because these torches get really bright and you're going to end up hurting your eyeballs if you're not careful and then basically we're all set to do the pour so you just want to keep your metal the flame on the metal the whole time [Music] okay let's see what happened with this one now oh man you know what something's happening where it's just flowing to the bottom but we'll see i think i just don't have enough silver here see it's going to be a bolo tie so you put your backing aside and then let's see what happens here almost look you got about an inch this is where the end of the design ends right there so it was almost enough silver but i mean that happens too like i said you don't uh can't calculate how much silver you're going to need but like i said mistakes happen we still got something there this is a good example of the metal like maybe too hot if you notice up in this area here it's really shiny right kind of washed out a little bit and the design didn't fully pour so that's another factor there so what's happening now is with this piece what i'm going to do is cut it off there and then yeah basically it'll be a bolo tie or i can make a ring out of this section here or that section but that's basically the process you can find me on facebook under lemayosi designs l-o-m-a-y-o-o-s-i designs you can find me on instagram at lamyuc designs all one word you can go to the native jeweler society website and you can find my work here the museum of northern arizona carries my work the herd museum winter sun training company pottery of the southwest in santa fe and contact me directly if you would like to order anything here is some examples of my work here i do cuddle bone casting this is a double tufa cast frog riding on a cuddlable cast river so really unique stuff you know it's i'm just limited by my imagination on this thank you very much

Channel: Museum of Northern Arizona

Views: 16,412

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Id: lQJy1xUFqwE

Length: 24min 43sec (1483 seconds)

Published: Tue Sep 15 2020