Silicone Mold Making - Three Different Ways

if you watch last week's video you know that I made this character in this week's video I'm going to mold him using three different casting strategies the head is going to I'm going to make a rotational mold and he'll be rotocast these pieces are going to be molded and cast using a one piece cut mold and all of these pieces will be open back molds three separate molds three separate strategies let's get started in order to make these molds some preparations are required the first is I'm going to make a shaped mold case and the reason I'm making a shape molding box for this is I don't know waste a lot of rubber the spouts gonna be right here and we're gonna have to fabricate that as well but that looks like a mold case to me okay so that's prep work on that we're gonna cut that out which we'll do in a second these open back pieces are just going to be attached flat and they're going to be molded just in this little box he's one of these pieces has been sanded flat so it has a nice flat back to put on the plywood and the other little bit of prep is we have a problem with holes you can't have holes well you can but holes can be problematic that hole becomes a long flimsy cylinder of rubber sticking out in the mold and the way we're going to solve the whole problem is we're gonna fill in the wax they don't have to fill in solid you just have to seal them up so we fill up the holes nicely you just have to fill it up so that rubber can't get in there yeah you know we needed the arm holes on the figure same way all right those are all full and now all we have to do is just kind of smooth them out a little bit don't show all right prep work done let's get ready to make the molds so I cut that shape I just drew out on the bandsaw and now the next step is we got a beeswax this stuff up because silicone rubber might stick to wood shouldn't but it might far better to put a sealant of beeswax on it [Applause] we're going to use this box by the way as the sides for a mole container that's why I'm coating it with beeswax again so that the silicone rubber maybe won't stick to the cardboard now that we have the box waxed will you just go ahead and cut it and we'll just cut it up to size okay so this is gonna be the bottom edge of one of our boxes you notice that I'm cutting through the paper oh well won't hurt it won't really hurt the desktop either frankly okay and I'm we're just gonna guesstimate here the way I'm gluing this thing together is with sticky wax which is this stuff and I just I hope and putting enough wax in there to get that to bond on there well we shall see and then the last piece will fit in there like that and with luck the whole thing will hold together well no soon enough I should work all right let me finish this up and we'll move on to the next step so the next bit of preparation required to make this mold is we need to put a funnel on this guy so we're going to use eighth inch wire and let's just go ahead and cut it off about I don't know let's say about like that all right well you talk about lucky guess work on that huh hoo-hoo okay so there's your spout now this is going to serve as a spout for pouring in the resin but more importantly than that it's also going to serve as the plug that we're gonna use when we rotate the thing you'll see what I'm talking about when we get there so nobody panic all right very good the next step is going to be sticking these pieces to the wood here we go I'm just gonna hit him with a little glob of sticky wax and position them into place make sure they are stuck down good that's all there is to that and the reason that I'm putting them so close together is because I want this box to be as small as possible and use the least amount of rubber as possible rubber is expensive we don't waste it nice they're all stuck on now all we need to do put the sides on the box which I pre-cut out of the same paper I use for the rotation mold for this we're gonna tape that all up and voila instant little mold box we're ready to go these two are next and this is going to be a cup mold one piece cut mold and we'll cut Pope so we'll be casting both of these in the same mold at the same time using this as our handy dandy pour funnel I'll show you what I mean as we do this job I began making this mold by drilling a hole in the heart there's a hole in my heart okay never mind that and we're gonna hook the hole the heart together with our happy aluminum wire don't need much how far does this go in not very far it's not gonna go very far in there either so let's call that like that see what happens and if it's too long we will shorten it um I'm gonna call that too long but you know what I could do two I'll show you something else I could do before I go to nuts I'm gonna call that a little bit too long not crazy too long but I also want to bend it a little I'm not using the force of the this plastic to bend I use my fingers otherwise you could have cracked and that would have been a mess and I've been sad I bent it so that it looks like that I could bent it I could bend it even a tiny bit more just have been though this thing just a tiny bit more that so you didn't see it's got a nice bend in it let's see if I over bent it very likely put that in there like that put this in here like that come on come on go in hey nice that's pretty much exactly what I was looking for now you go well alright now what now of course goes without saying the next step is what it always is sticky wax what what do we do in this world without our sticky wax and I'm going to on top there that and that together beauteous more sticky wax and here into the hole into the heart put those two together like that very nice now what we've done we've created a channel for the wax to run into the heart I'd like this sprue that we've made to be a little bit thicker a little bit heavier eighth of an inch is okay but a little bit bigger and a little bit more hooked together will cause the resin to flow in a lot faster and it'll let us fill the mold more rapidly so I'm just gonna build it up a little now we've got a channel goes like this we're going to pour it this way because it's gonna hang upside down in the mold but you got to get the air out and that is where our handy-dandy screw wax comes into play so we attach that to the highest point which is right there down here where it joins the heart we can afford to make a tight joint right here I'll get that well weld that's really weld that on there well so that the air we'll rise up out of the highest part of the mold which is the tip of the heart normally that would be the bottom of the heart but hanging upside down in the mold it's the top of the heart and it's worth it it's where the air is gonna rise out we don't want to make too huge of connection right here however and that's because that's gonna have to be cleaned up because this is doing double duty this is the body of our guy but it's also the pork up so oh I'm so clever so efficient with my working processes nice okay now there you have that done it's gonna wind up in this cup like that oh my goodness it just fits right in there know it all right perfect so once again back to the ever-popular sticky wax again you don't need a huge amount it'll stick don't worry like that and now I would say that we are very close to having three pieces here let's slide all this out of the way and recap shall we so there's your one this is going to be what's called a one piece cut mold this is an open-back mold and this is our handy dandy rotation mold and we're gonna rotocast this on the rota casting machine so this is going to be hollow and the reason this is going to be why am I going through all this trouble to make this hollow because this stuff magic swab this is pretty hefty it's heavy I'm using a rock and for you know a sculpture it wouldn't really matter but for a puppet like a poseable puppet this head is a lot of mass to balance on the little dinky body so it's being really handy if this was lightweight super lightweight hollow casting and that's why we're doing it let's get to it and pour some rubber now that that mold is poured so that the bottom sides are carefully filled and go ahead and just top it off and that goes pretty fast you don't have to be quite as careful because now there's no place to trap air and now all we have to do finish filling the box and pouring just enough rubber to coat the nose and while I have some rubber leftover from this last batch I'm gonna use it to put about an eighth of an inch of rubber in the bottom of the rotation mold I didn't get it on camera but what I did was I put some I cut some sticks of rubber from old molds and propped the magic sculpt master up about a quarter of an inch from the bottom so there's an air gap underneath the model and between that layer of still wet rubber so what I want to do now is I'm gonna pour the rubber it's only from one side in one spot and what will happen is the rubbers gonna run down in there it's fluid enough that it will just flow out from that spot where I'm pouring and push the air out in front of it like a wave and it should just remove all of the air from underneath it you can kind of see little bubbles coming up on the side but you can also see that the rubber is rising all around in an even ring around the model and that means that the air has been pushed out and we will get a really good casting otherwise you may trap bubbles now if what happens if we do truck bubbles well not a hell of a lot really it's just that much more work to clean up each casting fill bubbles patch them sand them that kind of stuff the better casting you make the less work you do later that's kind of the golden rule of doing this stuff that's why we work hard to make the best possible mold all right I mixed up another batch of rubber I've done this pour in several batches you take ten parts of the liquid rubber and you mix it with one part of the hardener so for instance this is a this was a hundred and eighty grams of the rubber and plus 18 grams of hardener brings you to 198 so you know you don't have to be that accurate so I went around 200 grams total let me just fine as always I'm gonna pour from the bottom up for the same reason I did on the other pieces I want the air to rise above and away from the model I want the rubber to push the air out of the way when you do it that way you really do get bubble free castings you can see it's pretty full you just need to be on top you don't have to pour a lot of extra now we're gonna see if we have enough should probably don't we're gonna have to mix up more but now let's go ahead and fill this mold hmmm question am I gonna have enough to fill this mold or am I going to come up a little short depends on how much I can scrape out of the cup right can we get enough to fill the mold that's the question we are so close to filling this thing yeah that's about all I can reasonably expect to get out of the cup so what I'm gonna do is I'm gonna cheat a little tiny bit and how I'm gonna cheat is just gonna move this down I'm just gonna prop it up a little bit of rubber there's a lot more rubber at the head end than there is at the tail end it's a tiny tiny tiny bit in there although I think it's gonna fill out okay and by propping it up a quarter of an inch I've got it about a quarter of an inch off the table by propping it up just that much I think we're gonna see if the rubbers gonna run down far enough to make that work out I think we're gonna be really really really close to doing it because the rubber continues to Sag down towards that end and I think I even only have about 1/16 more inch to rise and the the shape the form is completely covered so I think by god I estimated it with my customary absolutely flawless precision he says laughing yep do that okay now let's see if that overflows with time I'll take a look at it in a minute there's our beautiful three perfectly filled molds looking good I think they came out good I hope so we'll know tomorrow they're gonna like that we're gonna let them cure overnight as usual 24 hours and tomorrow morning we don't get these kids open see what they look like and with any luck we'll be making some nice castings tomorrow all right let's cut some molds see which one do we want to do first let's do the simplest one first the open back let's pull the tape off oh here we go I will definitely be doing some trimming you get about a flash around the edges of open-back parts like these fuse same things so there will be some trimming and cleanup none of that's going to matter to the castings castings are going to be just fine and as you can see the parts clean up just fine they are just pretty much completely unaffected by their immersion in the rubber no worries at all mold number two the one piece cut mold just get the cup taken off first plastic loves rubber so no problem now got to cut this open and in order to do that well first thing we didn't want to do is find the event where the air comes out which is that blue if you'll remember that blue wax rod we put on there and it is right there see that that's where we want to cut so here we go let us cut now we want to make a very jagged cut you would think that you would want to make a really clean perfect cut oh no that's not what you want to do you want to make a really jagged cut so that when you put the mold house back together again the two sides interlock with one another because they're so jagged and rough see how I'm going back and forth and making a sawtooth like pattern see how nice and rough that is and see how they lock back together again Dada that's why you do it see how they lock back together that's counterintuitive to how you would think you wouldn't want to make a mold and it's one of the things you have to learn about making molds that's the trick now I've got to cut down far enough to get past a connection between the body and the heart and I just did that so now you can see I can see the top of the heart and you can see how it connects to the body I hope you can see that in there bring that up see that it's kind of like a surgery actually okay now the trick here is we want to cut as little as possible but still release the parts so in order to achieve that goal we're gonna cut the top part out and to the sprue okay I think that's enough to get the heart out yeah came right out perfect and you see the rough halves of the mold they just come back together and that just makes an almost invisible parting line no cleanup that is gonna make nice tight castings all right to four to the rotation mold is by far the most interesting one and the one that's going to require the most work because not only do I have to cut this mold free I've got to mount it to a rotating machine and in order to do that I'm gonna have to have a cradle meantime we have to cut this thing open again with the jagged cut so I'm right at the part see it I don't know if you can get can you see it right in there I see there there's our part let's just cut it open just pulled the funnel out now we're gonna need this funnel again this is this we're going to cram back in the mold every time we make a casting as our stopper but you can see things are going well this mold has a good shape because it's very wide and big at the base which means I hope we're not gonna have to cut too much along the sides but this rubber has a high modulus of elongation so da da there he is hey pretty clean pretty clean let's design and fabricate a cradle I made a little rotator just for small parts like this so what I'm gonna do now is we're gonna make the cradle we're going to attach this the rubber mold to this inner frame so we can spin it in space there's my basic piece of wood so this is gonna sit on there like that now the thing is if you put it on here like that it's ridiculously out of balance that's not what you want so what you want is you want it more like this so I need a couple of five-inch pieces of this let me go cut that alright I got them cut and now we just need to put them on with some five-minute epoxy no worries easy peasy then the mold will sit right in there and the whole thing will attach to the frame with four screws alright like this looking straight down at it you can't really see it but it's more centered in the cradle and that's going to give it a much better balance I'm going to cut this on the jig saw these shapes and these are just going to be like tabs that the rubber bands are going to wrap around eventually this piece will fit like that and it'll be all held together with rubber bands wrapping around beautiful alright let's go cut them on the jig saw what I have done it was broken out the rubber bands I'm very curious as to how this is going to all fit together so let's pull out some rubber bands and see what we get let's see how this is gonna work put that on there like that okay then the concept here is take a rubber band pull it over and go like that then over here just because we have to be colorful and flashy take another colored rubber band go over here like that holy moly look at that it's just it's like it's almost like I know what I'm doing huh and then let that yellow rubber band make sure that that plug doesn't fall out something like that but that is just gonna spin that thing like a crazy man and now all we have to do is take four little screws and attach that to that and we are done and ready to go [Music] okay that's in place let's get this one in place I think these two halls are lined up pretty good all right now we're in business now if this thing shifts around be honest probably two of them would held it would have held it this is such a small object all right we're almost ready to go and while we're on the theme of rubber bands let's put the rubber bands on the cut mold those are way too big so what do you do I used to have a collection of rubber bands of all different sizes until I woke up one day and said I'm an idiot all you need to do is make your rubber band fit your mold could not be simpler than that just tie a little knot in it and you can custom make a rubber band to fit pretty much any sized of mold including you can tie Barber bands together for big molds okay so three is gonna be enough as you can see you cannot see the party line on that mold well you can if you really get at your scanning electron microscope eyeballs you can see it but that's a nice clean partying line we're gonna have very little clean-up on those parts it's time to mix some resin and pour some resin well let's get on with that project no time like the present as you can see this will be a nice dark pink when it sets up probably let's mix it up good since we already did the first set over here we know how much we're gonna need some where's the vent or the big ones first that way you can dump out a lot of the material well from the biggest to the smallest yeah more control over the small castings when you have less resin in the cup when you're pouring an open-back mold you can't always take a stick and just kind of scrape it like that well let's slide these into the tank this pressure pot will crush out all of the bubbles and that's why we love it at the air in and we're golden okay I think it's been about 20 minutes and see what our witness cup tells us see how hard that is that's why we love witness cups because they this cup is telling us what's going on put the castings in this tank don't have to guess just the way I like it let the air out let us see what we have oh yeah very pink very very pink hmm all right let's see here I'm gonna take this off so you can see it without moving the camera I'll open this thing up there you go very nice looking good oh yeah that's nice that is very nice so good castings coming out perfect as to be expected see some of these let's look at his little pants part there's the little pants part also looking really good here's the nose get the nose out oh yeah nice oh yeah you know you know you could you can gasp all of these things in solid colors if you wanted to and not even have to paint could do it that way I'll peel the rest of these out and we'll keep going alright we're gonna make rotation number one see what happens but I'm just stirring up resin I think I have way more resin than I need so let's get this thing put down and pour it in place down the hatch it went let's get this thing in place that kind of struggle to get the cap in it'll go and indeed it did go nice okay that's gonna hold I'll put the yellow rubber band on there just to make sure but I think it's gonna hold let's spin spinning spinning alright this thing is spinning like a champion and you just keep this what you want if when you spin is you want full random motion spin it spin it I made this rotator yesterday I think and it's just is very simple made out of scrap wood and four screws I couldn't be more pleased by how well this works it's still quite liquidy in the cup but I think it's gelling is it getting warm yeah it's getting warm so it's starting to gel so we definitely want to keep it rotating it's definitely starting to gel up I don't want to stop we don't want to let it rest I just want to keep it moving all different directions forwards backwards upside down just keep it moving and then the cup will tell us when we can stop spinning oh yeah starting to gel in the cup all right Simon time let's see oh yeah yes indeedy it's hard it's ready to pull guess we'll just pop off the rubber bands and free our little boy there we go easy-peasy and see what the cap looks like nice ok it's looking good that sealed up okay I put some release agent on this cap speak is because urethane will stick to urethane so but now we not with a release agent on and it won't pull this boy apart ooh looking good looking good so far looking good so far now I didn't cut it down very far so I'm gonna peel it off this way just using the stretch of the malt oh yeah really good and light much lighter now I think I could cast it even lighter than that I cast a 60 gram batch I think I could cast a 45 maybe but that's a significant improvement over the 135 grams that the magic sculpt original weight so not bad all with some slight mold cleanup but really pretty clean looks good very pleased here's our project as you can see I made a bunch of them in different colors we started with the originals and the gray magic sculpt and then we just cast up all the different pieces in different colors I would argue that I've made more more of my living as a mold maker because almost every project I've ever done has involved making copies of the original sculpt or the original sculpt was made in a fragile media like wax or clay and then the final version of the piece had to be made in some durable material like resin and that's been true of commercial jobs as well as gallery and fine art work so I strongly recommend you learn mold making and casting it's a lot of fun and it greatly extends what you can do in your shop next week we're going to assemble and paint one of these characters and that should be a lot of fun see you in the next video

Channel: Robert Tolone

Views: 379,994

Rating: 4.8590908 out of 5

Keywords: silicone mold making, silicone molds, rubber molds, how to make molds, how to make silicone molds, make rubber mold, casting urethane resin, cast resin, casting plastic, mold making, character design, sculpture, puppet making

Id: 1qOwem_ll68

Length: 33min 41sec (2021 seconds)

Published: Fri Nov 01 2019