aive
New Member
Posts: 5
|
Post by aive on Nov 2, 2018 14:24:03 GMT -5
Hello, I'm looking for advice with silicone face casting
I have head mechanism with servo motors and quite rich range of position controls for toy, which should have facial expression animatronics.
I have 3d printed head with face model, which can be used as cast for silicon mold form.
I have some experience with casting of concrete forms, but I never have a deal with silicons, in addition with respect to animatronics.
I have a theoretical idea how to fix and connect the motor element with a silicone form, but I don't know, which material I have use to get appropriate quality with good flexibility for such elements like eyelids or lips, because I have quite intensive movements set for different expressions
I understand, this art and technology requires skills, but nevertheless, I would also like to hear any other advice for a beginner
|
|
|
|
Post by notoes on Nov 2, 2018 19:09:43 GMT -5
Wow that sounds like a cool project, would you mind posting pictures of it when you're finished? I'd love to see how it turns out. Now onto some help for you. Since the silicone needs to "move" I'd recommend the Flex series for its "stretchiness". They're under the Resins section, the higher the number the harder it is. I've personally tested a bit of Flex 30 and it's soft and stretchy so I think the Flex series will work for that application. Be warned that it does take a long time to cure and you will need to let it hit full cure before trying to remove it from the mold. Since what you use would need to move, so the Flex would probably be better even though it's a resin type. The HS (High Strength) series silicones can handle rough handling but the Flex resins are made specifically for moving parts so I think it would be better.
You said you're using a 3d printed head for the form so I'm guessing that the silicon would be used as a "skin" right? If so I would "brush" on the Flex with a paint brush to get an even layer and you might want to do more than one layer just to be sure of the coverage. A little heat (heat gun or hair dryer - your choice) will help the cure along and help stiffen up the layers a bit faster so you can put on another layer.
Most importantly, take your time and don't rush, you'll get a better end product that way with less stress. Also do a small test on something other than your head mold, just so you have an idea of how it works before you do it on the real thing.
|
|
aive
New Member
Posts: 5
|
Post by aive on Nov 3, 2018 5:27:55 GMT -5
Wow that sounds like a cool project, would you mind posting pictures of it when you're finished? I'd love to see how it turns out. Now onto some help for you. Since the silicone needs to "move" I'd recommend the Flex series for its "stretchiness". They're under the Resins section, the higher the number the harder it is. I've personally tested a bit of Flex 30 and it's soft and stretchy so I think the Flex series will work for that application. Be warned that it does take a long time to cure and you will need to let it hit full cure before trying to remove it from the mold. Since what you use would need to move, so the Flex would probably be better even though it's a resin type. The HS (High Strength) series silicones can handle rough handling but the Flex resins are made specifically for moving parts so I think it would be better. You said you're using a 3d printed head for the form so I'm guessing that the silicon would be used as a "skin" right? If so I would "brush" on the Flex with a paint brush to get an even layer and you might want to do more than one layer just to be sure of the coverage. A little heat (heat gun or hair dryer - your choice) will help the cure along and help stiffen up the layers a bit faster so you can put on another layer. Most importantly, take your time and don't rush, you'll get a better end product that way with less stress. Also do a small test on something other than your head mold, just so you have an idea of how it works before you do it on the real thing.
Hello,
Thank you for your feedback and answer
Sure, I will post results, but now I'm very far from the result regarding the casting of silicone skin. I'm trying to figure out with number of questions:
1.
So, with Flex 30 rubber how material looks in result, for example like this transparent forms, or I am able to get something like this example with skin color, in this case without coloring of surface or adding paint in rubber, I don't know, maybe it is some kind of Medical Silicone TPE. If I get it right, color Honey means that is a color of material without paint. What kind of paint should be used for first test
2.
What is approximate mix proportion for side (part) A and side B as shown in this example it is Mix Ratio 1:1 as given in specifications, but I'm not sure if it must be some different proportion in my case, because it says that proportion depends on weight, my head form sizes is 10x12x14 cm
3.
I'm not quite understand value of HS (High Strength) by this specifications for particular product Flex 30 rubber, so Tear Strength (ppi) 50, I think in my case it is important to consider tearing effect with intensive movement and long time term, and Tensile Strength (ASTM D-638) (psi) 270, which must be "High Strength" I guess, Flex 30 has lower number in list of 40, 70, 80. So, if I correctly understood, Flex 30 is the most elastic material, but at the same time most affected with tearing, last seems not suitable in my case. But I'm not sure, if I understand values correctly, maybe I should look for Shore Hardness (ASTM D-2240) 30 A: Product Flex 30
Color Honey
Mix Ratio 1:1 by WEIGHT
Open time 5-7 min.
Demold Time (100 gr. Mass) 2-4 hours
Mixed Viscosity (cps) 660
Shore Hardness (ASTM D-2240) 30 A
Tear Strength (ppi) 50
Tensile Strength (ASTM D-638) (psi) 270
Elongation (in./in.) 800%
I did not touch the material, but this form examples looks like thick rubber and not enough elastic. I want get result, not so natural as in this masterpiece, but as example equal by flexibility, especially with eyelids and mouth lips in my case. This one also looks quite flexible, not so realistic as previous especially with painting over surface, but I do not need such a natural coloring of skin itself, my main goal is material quality and flexibility with the required intensive and long term movements with facial expressions
4.
I think, 3D print form can fulfill the role of cast for future silicone mold. So, it should not be a full filling of form, but casting layer by layer with paint brush and help of heat, If I get you right, air flow causes hardening of rubber, to put next layer if necessary faster, to make it not too thick, keep able to express movement, because in result I want get thin skin layer attached to mechanical scull. But how to connect the cast parts, such as the face and the head itself with nape, ears etc., or I have fill rubber inside the form to cast all together, then how do I get thin layer, same way as with brush. Or better find some kind of compromise with the gap between forms in entire assembly, what sounds reasonable for the first time experience
5.
And last, with concrete casting I've used paraffin oil in case of using of clay for sculpture and plaster for mold. I'm not sure, if paraffin oil as insulator between silicon and form and plaster mold is a proper way for rubber casting. Seems like, it is not the best way for rubber, according to examples on internet, but I'm not sure what I have to use. Besides, I would like to take into account the fact, that maybe I will not use the 3D model form print for cast and I will make face for example out of clay.
It would be generally good to have some kind of guide covering relatively all basic rules of casting with rubber, but I did not find something like this for beginner in internet
|
|
|
|
Post by notoes on Nov 6, 2018 7:32:28 GMT -5
Sorry for the late reply, the power unit on my computer died and I had to run all over creation to get a new one (since my backup computer failed and I couldn't get online) and yesterday was spent playing catch-up because of it.
And feel free to post work in progress pictures, those are good too.
1. Without color (Alumilite has colors specifically for their products and I have not had good results in using anything else), the Flex 30 is a deep honey color (like the honey you see in the grocery stores) similar to the Side B color except it is a little "deeper" color. Here's a picture of what it looks like as a final product without coloring, ignore the bubbles - they're not on the surface and this was just a test piece for me so I didn't worry about getting them out. 
2. I would still do the same ratio since if you go off ratio then it will affect the curing and you don't want that. Since you'll be brushing it on, I would say to just mix up small amounts at a time - like 2 or 3 (total) ounces or if you're like me and use a gram scale, 100 to 200 grams at a time. Then just brush on until you have it all on and if you need more, it's a simple matter of mixing more - the Flex 30 will stick to itself with no problems so it's fine to add extra to a previous mixing. Without just mixing up small batches and brushing it on, there's not really a good way to calculate how much you'll need per layer since this won't be a solid item (like a casting piece similar to my picture).
3. For that I think you've got the right idea, go for a higher tear strength than the 30 - I didn't think of that part and was thinking of the "flex" aspect and not the fact that it will have a lot of repeated movements. The 50 to 70 (maybe even the 80) would probably be better. The higher numbers have more strength and may last longer than the 30 with repeated movements.
4. Yes, layer by layer is the way to go if you're not doing a "solid" item and are attaching it to the 3D head. It isn't so much air flow that causes the curing, it's warm air - cold air doesn't actually do much to help. The layers will act like a "face mask" to the 3D head so to you'll need to control the amount that gets into any cracks and crevices with the brush. Now will the mechanisms be inside the 3D head or have a different type of "support" between them and the Flex covering? If you can, can you post a picture of the mechanical skull and neck area? From what you've said, I'm thinking the Flex cover would act like a fabric cover but you would need some kind of temporary support under it so it doesn't seep into spots you don't want it to go.
5. The thing with silicone is it's very "forgiving" when casting it against any other material that is not silicone. When I cast resin in silicone molds, I almost never use a release agent (where you would use paraffin oil). Silicone only sticks to silicone so unless I was doing a two part mold where one half has to separate from the other half, I wouldn't worry about it sticking to anything else. And even though the Flex is a resin, it acts a lot like silicone. In your case, if you ever need to remove the Flex from the 3D head, you would most likely only need to pull it off (if you want it in one piece) unless it seeps around something then you'd need to carefully snip it open with scissors.
For a basic rules guideline, it depends on what you are using the silicone for. I found this to be the case when I first started casting myself so now I do what I can to help others here. You might have to set up a folder on your computer for some notes and tutorials you find like I have on mine - I even have it organized by products with each in its own folder. You're always welcome to ask any of us here for help, some have used a wide variety of products and know how each performs on different applications and are willing to answer your questions. |
|
aive
New Member
Posts: 5
|
Post by aive on Nov 6, 2018 11:00:32 GMT -5
Hello,
Thank you for answer again
I have outgoing questions
1. If I can't use other pigments, I should get Alumilite Dye I guess, but I can't figure out with names, seems like I need Opaque and not Translucent colors, so can't figure out what is what: Opaque colors include: white, black, florescent red, flo. orange, flo. yellow, flo. green, Caucasian, African American, and Native American. For example Caucasian, it doesn't seem like it's just a color name, then it turns out that it is already mixed color by particular race skin color, I can't find any example of result
3. If I will use Flex 80 instead 30, to get more durable quality of resin with intensive movement load on material, will i get flexibility then for such places as eyelids and mouth lips, eyeball attached to silicon and even more active mouth lips movement attached to pin of motor mechanism (of course with taking into account the correct thickness and cuts in mouth and eyes). I'm a little confused about this, if dense consistency means less elastic, then which I've to use?
4. Mechanism doesn't yet looks like a skull for the skin of the face. 3d printed face is a just a model, sizes and design version, not attached somehow as scull or mechanically to assembly, possibly will be used as form for mold, or as I've said above, maybe I will make new one from a clay. So, mechanism is a several number of motors located on the frame in accordance with the structure and size of the future face, including mechanical connection ends for each freedom degree range on its place. Motors set up provides necessary movements for head and face from control application. Supports set of movements for separate parts, mouth, eyes, neck. Is is quite short range movement, but very intensive and fast, about 3-4 messages per second and preferably with large margin of lifetime in terms of execution and rubber conditions. I think, some parts of skull must be hard and fixed as carcass, forehead, cheekbones, nose, separately jaw. First of all, I need figure out with animation of the face, after this, neck part seems easier. For example if jaw requires fixed connection point with rubber, mouth lips area on the backside of mask must be attached to mechanical pin with some kind of mounts in several places to use all exist freedoms degree, including mechanical reference. Eyes will be attached to eyelid with mediate part to open, close eyelids and move x/y direction with eyeball.
This is not a good developed example below, I've build it just to show you idea, I don’t even know if it will be possible to apply this method with rubber, maybe such an intermediary or directly connected part will easy slip out from silicone nest with movement, and I'd rather use some glue. But it seems possible, if I am able inject the expanded side of the connector into the silicone mass and firmly fix it there, then to make the connection with the motor part of the mechanism. Part must be attached to the backside of the silicone mask and ensure the connection of this point with eyeball or upper lip for example, mouth corners etc. So, I'm wondering if it is possible, during the covering of inner surface of plaster mold with brush, include such part into silicone from backside to get socket as fix point. If so, then what kind of glue can be used to connect for example Nylon, PLA or ABS part with silicone rubber? I think this will provide a good connection in several places, not limited for movement, for both movable and static places on face, as well as a conveniently removable shape:
So, how I imagine this task. For example, it can be a 3d printed web connected with temporal supports and connectors on the ends, matches the right places on the face skin from inside. Web with tiny connectors can be putted into the rubber mass together, which must be neatly smooth out on connection places with stick tool. After hardening of mass, pull out web with connectors and add glue inside voids, put connectors back to keep it there forever, cut supports web from glued connectors. I'm not sure, but I think this should work in case if I can successfully locate connection void in right places and then use glue to join. In words sounds simple, but in practice, it seems to me, will be more difficult, locate each connector in right place inside quite thin layer of rubber, in spite of the fact that the calculation of sizes for volumetric form will be accurate with supports web, which also should helps to do it at the same time. Anyway, I hope it is possible. So, I found this Sil-Poxy Silicone Adhesiv, but I'm not sure, if this is what I have to use with Flex 80 or 30.
5. I found this mold soap which can be used with plaster mold and silicon, but since you say that it is not necessary, I will not use it yet
6. Additionally, I'm wondering what is a role of liquid thickener using with rubber casting
|
|
|
|
Post by notoes on Nov 7, 2018 15:19:06 GMT -5
Okay let's see if I can be of help on the dye part.
1) The dyes are concentrated and should achieve the labeled colors when added up to 0.5% of what I'm assuming is of the total of Side A and Side B combined. I say assume since I haven't tried coloring the resins myself (and I have to say that I don't see any examples of the finished colors either). What I myself would do is since this is a animated head, I would pick the color by the race skin color. The directions say to add it to side A before mixing Side A and Side B. So I would measure out Side A, drop in a couple drops of the color (since it's a dropper type bottle) and mix the color in. If the color mixed with Side A is the right color, then go ahead and mix in Side B but if it's not quite there then drop in a couple more drops. Repeat mixing the color and Side A until you get the shade you want (be sure to mark down how many drops you used for future mixing).
3) Flex 80 will be the hardness of a "roller blade wheel", so you might be better off with starting with Flex 70 instead as it's more of the hardness of a "car tire". The 70 might be more elastic while still giving you the needed strength even though you'll be doing layers and not solid objects like a regular casting.
4) I think you can still use the 3D print as a form, just be aware that if you want to remove the Flex (since it will act as a skin) then you'll need to carefully cut it. Good thing is that once you have it off the 3D form and on the actual head, you can mix up a small amount of the Flex to cover/reattach the cut edges so that it stays on and you don't have a seam. The Flex won't let you "sew" up a seam like you would with needle and thread but it will stick to itself to hold two edges together.
Now as to how to attach the Flex to the separate parts such as lips, jaw, etc I think you might could "embed" the part in the Flex to a certain point by brushing the Flex onto the inside like you mentioned. Taking your picture as an example, you could embed the curved "top" area up to the edge of the hole but not past the edge (where the Flex would go into the hole) in the Flex and that should hold the Flex in place without getting in the way (or hurting) the electronic components. Now as for gluing the Flex, it is a resin so it most probably can be glued with super glue BUT personally I have not tried this so I can't say if it will work or not. I do know that you can't really glue a silicone to anything (I've tried that and couldn't find anything that worked) unless you were gluing two silicone surfaces together.
So embedding would be a better thing to try for attaching to the supports but you also need to get the Flex to stretch over open spaces. Can you use something like a mesh fabric in your project? Instead of using a 3D printed web you have to remove later, you could stretch some mesh fabric over the open areas and glue it down then pull the cured Flex over top of it. The mesh fabric would be permanently attached to the form and you wouldn't have to remove any connectors as you could smooth out thin spots by going over them with more Flex. Would that work for the open spaces?
5) Yes I don't think it will be needed.
6) I don't think that thickener would be much help plus as it's meant for silicone it probably wouldn't work on the Flex as the Flex is a resin type.
I hope this helps and if anyone else has extra information/experience please chime in - I'm no expert and am always willing to learn new things.
|
|
aive
New Member
Posts: 5
|
Post by aive on Nov 9, 2018 8:19:08 GMT -5
3) Flex 80 will be the hardness of a "roller blade wheel", so you might be better off with starting with Flex 70 instead as it's more of the hardness of a "car tire". The 70 might be more elastic while still giving you the needed strength even though you'll be doing layers and not solid objects like a regular casting.
Hello,
Sorry for late response to your answer, once again thank you for so attentive support. Actually I've figured out with all my questions with your help.
I think Flex 40, or as you've suggested 70 would be appropriate consistence in my case to try first time.
The only thing I haven't quite figured out yet:
I looked through several delivery services, and only one provides the opportunity to transport this material by air, because unlike the others, they uses some specific certificate. I am not good at chemistry, but it gives reason to suggest, that the rubber contains chemical substances that I need to handle with knowledge and care. I assume that the instruction will be attached to the product, as well as link to the product also already contains this information Technical Data Sheet, and Safety Data Sheets, which says everything about my question, but would be very useful to get some basic instructions from you too, just to not overestimate, for example use hazard suit =), or underestimate rules, for example do not take into account some important condition of caution due to the human factor, for example, use anti-flu or anti-pollution respirator instead proper safety mask. I'm really not sure what I have to use. Here is the conclusions I came to on my own, I don't know if I managed everything, please inform me if i made some wrong choice or just missed something:
1. Keep away from children (material itself and isolation during casting process)
2. Keep away from fire, heat and other provoking circumstances, including different chemicals
3. Use some respirator mask for example Spray Paint Mask but I'm not sure if such mask is appropriate for this work. 5. Instruction says "Wear suitable protective clothing", but I'm not sure what it means, maybe something like this Chemical Protective Suit6. Use rubber gloves
7. Work inside not residential and well ventilated area 8. Keep in a dry, dark place with normal room temperature
|
|
|
|
Post by notoes on Nov 10, 2018 9:09:28 GMT -5
No problem, it's what the forum is here for - to help others with any problems or questions. If the Safety Data Sheet and/or the Technical Data Sheet aren't in the package, you can also download or read them on the Alumilite website when you order the Flex. A little caution is needed when handling the Flex but it's not so bad as long as you do it the right way.
1. This is normal with most anything - they even have this warning on some molding clays (though I don't think it's on Play Dough) and even some glues so it's just a "usual" precaution to protecting young children who might try to ingest it.
2. Just keep your working area clean and don't work next to an open flame and you're fine.
3 I've never used one for my resin/mold work. I don't even use one when I hand-paint glass but then again, my work area is very open.
4. Not really needed but it's always good to cover all bases.
5. Just wear something you don't care if you spill something on - similar to not wearing a tux or an evening dress to paint in.
6. Yes this is actually something you should do with all resin and mold materials, a good pair of disposable ones is all you need.
7. If you have the (very) well ventilated room, it's fine to work in your house.
8. Just don't store it outside where the weather fluctuates way up and way down and you can get moisture contamination if you don't cap it tightly.
Now here's what I do when I work with any of the resins and it's what I've done with the Flex 30:
1. My kids are four-legged and I don't keep my stuff where they can get into it plus they're taught not to go near it.
2. I have two work tops - one is a board and the other is a counter top cut out. When I work with either the resins or the mold materials, I don't have anything else sitting on or near either work top. If it's within arm reach, then it's too close to what you're working on. And if it's not going to be part of the finished product then it doesn't need to be there. Plus just don't have your work area next to an open fire (which you shouldn't anyway).
3. I have allergies so I'm sensitive to smells and fumes even though I can't smell a lot and I don't use a mask. Even though when I "eye-ball" an amount and I bring my eye down to the level the material is on, I still don't have any breathing problems or wear a mask.
4. Nope I don't do this either. The only reason you would normally use the glasses is if you're splashing things around and if you just be careful to not splash, it's not necessary to use them. Or if you're grinding/cutting/smoothing the cured resin where you can have pieces flying around.
5. Again, just wear something you don't care if it gets messed up. If you really want to or don't have anything old to wear, you can always wear one of those "painting suits".
6. I always wear disposable glove, they're cheap and make cleanup so much easier. Once you're done, you just pull them off and toss them.
7. I work in my kitchen. It's a corner room so it only has two short walls on one end with two wide open walls (opening to the dining room and to the living room). There is a ceiling fan in the dining room that runs 24/7 and I keep a heavy duty floor fan running 24/7 at my back. So fumes go halfway across the room before they can rise to my nose.
8. This is a normal precaution that is sometimes not strictly followed. If you read the backs of kitchen cleaners, you'll see the same precaution and those are things that normally end up just under a sink. My materials stay dry in room temperatures but not normally in a dark place. Someone here holds the record for "oldest bottles of resin that are still usable" and I believe he said that they're just under a work bench and I'm not sure if that work area is heated or not. So two out of three conditions will work fine. Just be sure that the caps are on as tight as possible (when not pouring, cap them as soon as possible) and they will be fine as long as they are not exposed to freezing temps or 100 degree weather.
Feel free to post any in progress pictures you might have questions on, we don't mind and it might help someone else.
|
|
aive
New Member
Posts: 5
|
Post by aive on Nov 13, 2018 8:05:37 GMT -5
So, I just have to wait for the materials and start to experiment, but I still have two question:
1. Which material I can use to take mold from a clay, plasticine, 3d printed, or any other sculpture form material, to get soft and useful mold for multiple castings with particular Flex 40, instead plaster mold
2.
Now I understand the values of all this data used in Alumilite specifications description, also used by other manufacturers with products specification.
According Flex 40 example, I've attached a link to each value with explanation I found:
Mixed Viscosity (cps.) 660
But some sources uses different values. I'm trying to figure out, how to read and compare, for example with same Flex 40 and get same information, for example with data below, which is also silicone rubber for casting. I understand only Shore Hardness, must be same 40 I guess. With exception of mix ratio and demold time, example below provides only given data instead of known values, used with Flex 40, maybe somehow equivalent. Anyway, all this values and numbers are not clear to me. Even if I am able to find information, for example on specific gravity or any other given value, it doesn't helps me in terms of comparison or understanding approximate consistency, same way as with Flex 40 specifications: Mixed Viscosity (cP): 22,000
Shore Hardness: OO40
Specific Volume (in 3/lb): 25 Specific Gravity @ 25°C (77°F) 1.1 Shrinkage Upon Cure: Nil
|
|
|
|
Post by notoes on Nov 16, 2018 7:09:29 GMT -5
Sorry for the late reply, I was working on a rush mold order.
1. HS (High Strength) series of mold rubbers are some of the best "all around" mold materials for casting against a variety of materials without having trouble with curing. All "tin cure" mold materials do good against a lot of other surfaces but the HS series are fairly soft (#3 being the softest to the touch and #1 the stiffest) but can handle a lot of rough handling or repeated use. Now if you use it with the Flex resin, I would say that you would have the best results with being sure to use a "release" agent in the HS mold. My reason is that both the HS and the Flex are "soft" types and would prefer to stick together more often than not. With molds and castings, one surface is soft and one is hard - the hard surface will pop right out of a soft one when the soft one is flexed. Now as for a release agent - Vaseline or a spray release (even cooking oil can be used if that's all you have on hand) is good. A release spray meant for being used between two silicone surfaces can also be used. Just be sure to use a thin layer - you can always take a paper towel and gently wipe it out to be sure that it's thin enough. Thin as in thin enough to barely feel with your finger but not enough to see with your eye.
2. I have had a lot of trouble understanding those things too so you're not alone. What I usually have to do is look for the descriptions that provide an answer in more "normal" everyday terms like when they compare the "hardness" to a rubber wheel or car tire. Or say that the "mixed viscosity" is the consistency of thick honey (meaning it moves as slowly as pouring honey). The only one I usually understand otherwise is the "shrinkage upon cure" and that means that when the casting is fully cured, it stays the same exact size as it was on day one of the cure timeframe. In other words, your mold will never get smaller. As for the rest, I'll have to hope someone else has a better explanation of them than I do because I still don't understand some of them myself.
I hope at least half of this helps.
|
|
