1. 1 Week Ago  Feb 11, 2018, 3:05 PM - Sealing a Paper Master For Molding? #1

    Thanks in advance for any insights. I'm new to molding and casting but the creativity and sharing of the prop modeling community has been so amazing. My normal gig is designing pure origami sculptures, but i am branching out into molding my designs and making cold cast origami sculptures. One of the big hurdles has been sealing the various creases and voids in the folded paper models to make a "water tight" master. I have been getting some good success but my stretch goal is a dragon that may go beyond my current skills and materials. I am wondering if there are some great products or alternate techniques out there that may be a better fit.

    I use sculpy to fill large voids and a range of white glue and super glue to seal layers of paper together. It has been important to me to maintain the paper texture so i have avoided thinks like dipping the model in resin, but am open to it. My current approach has two large issues:
    - the sculpy separates from the paper leaving cracks for silicone. So a clay with a little tackyness would be amazing.
    - the glue always has a few little pin holes or spots where the silicone creeps in. Something low viscosity with a short dry time might be a life saver

    Any help is much appreciated. I have been makings mostly 2 part molds, Im probably going to split the dragon it into 5 molds (head, tail, wing, wing, body), but i am completely open to better molding ideas to deal with all the overhangs undercuts and other assorted difficulties, be that a glove, matrix, or other mold type.

    Recent Complete Cold Cast Origami Lion

    The next project up is this Origami Dragon (full of nooks, crannies, and places where multiple layers of paper are stacked that the silicone is going to get in and not want to come back out of)
    Last edited by maddoghoek100; 1 Week Ago at 4:30 PM.
  2. udog's Avatar
    Member Since
    Feb 2016
    1 Week Ago  Feb 12, 2018, 4:51 AM - Re: Sealing a Paper Master For Molding? #2


    Never made a silicone mold of a paper model like this, so these are just thoughts:

    About bulk filling the mold with sculpey, there are stickier clays around (not self hardening that I know). Can´t think of a brand now, maybe someone can tell.
    But there could be a work around to that. What about a rotocasting PU resin like Smoothcast 65D:
    Not sure how the paper will stand PU resin but you could pour small amounts of material inside the paper model and rotate the model till you get the firmness you´re after. It´s a resin designed for rotocasting and the gelling tempos are slow. It would be cleaner and easier than theclay as I see it.
    It would also seal the interior of the model .

    As for sealing the paper. have you made tests with a fast curing silicone directly over the paper, previously released with, for example, a silicone spray like Ease Release 200?
    You could also try to seal it with spray paint (acrylic, the fast setting ones), epoxy parfilm?...shellac?. Not sure how this would affect the texture.

    "the glue always has a few little pin holes or spots where the silicone creeps in. Something low viscosity with a short dry time might be a life saver "

    I would say a higher viscosity silicone, that would make it harder for the silicone to get into the pores, and fast setting as you say, LOwer viscosity would be more pourable, thus it would be easier for the material to creep in the pores.

    There are many of these around, or you could always thicken a little your silicone (with the correct chemical thickener) to increase the viscosity. How are you molding this, brush up or pouring?. What silicone?
    Take a look into Smooth On or Polytek websites. They have a wide range of silicones with variate viscosities and setting times. I´m sure you will find something that suits. Or at least it will be a guide, then you can look for what you want to other suppliers.

    Anyway I would allways make small scale tests before. It will help to avoid problems.

    Looks like an interesting project.

    Good luck and tell us about it.

    Just thoughts.
  3. 1 Week Ago  Feb 12, 2018, 4:36 PM - Re: Sealing a Paper Master For Molding? #3

    Thanks for the feedback. A few more bits about what i have been using and how i have been doing things to date that may be helpful. Mostly settled on some of this approach through trial and error (mostly error) and tips from youtube (thanks tested, punished props, and smooth-on)

    I am using all smooth-on products at the moment:
    Molding: Oomoo 30 in 2 part molds and dump molds, but i do have some rebound 25 and thivex on hand. I dont currently have the ability to vacuum de-gas,
    Casting: Smooth Cast Onyx, primarily rotocasting and I do not currently have the ability to cast under pressure

    I am coating my molds in 325 mesh bronze or copper powder, dumping the excess in my resin (1/3 metal, 2/3rds resin). I am backfilling the hollow part with steel sandblasting pellets to get to my target weight and using some extra resin to lock all the pellets in place so is a solid block.

    A quick snap of my lion molds (body not shown), masters, finished object, and a little actual folded paper one:

    Reading your comments gets me thinking for the first time that maybe a beauty coat of thickened Rebound 25 brushed on would not seep in as much as the oomoo and I think I would still not have to vacuum de-gas. Then I can fill the mold box with oomoo for structure.

    I have not yet attempted a jacket mold. My original idea for the dragon was to attempt to do it as a jacket and cast as a single piece with fill holes in each of the feet (which is why I have the rebound on hand). I could not quite conceptualize how I would vent the wingtips tail and nose. I’m open to doing the color change just as a patina, rather than casting separate parts like i did for the lion.
  4. clonesix's Avatar
    Member Since
    Sep 2002
    1 Week Ago  Feb 14, 2018, 12:36 AM - Re: Sealing a Paper Master For Molding? #4

    Molding paper?

    The two issues that come to the top of my head are: 1) it is the deep folds that are likely to trap the Silicone RTV. This will give you a thin, floppy fin of RTV flopping around the mold, and will eventually tear out. So anywhere that has a deep fold, that needs to be filled with clay.

    2) the weight of the RTV will distort the sculpture, so you may need brush on several light coats of RTV over a period of time to prevent distortion.

    Isn't origami paper already sealed? If not, try a parchment paper, or a light coating of Crystal Clear.
  5. 1 Week Ago  Feb 14, 2018, 2:42 AM - Re: Sealing a Paper Master For Molding? #5

    You definitely hit on the two primary issues i am having, said differently i am having difficulty making the model "water tight" more in the 3d modeling sense than in the actual absorption of liquid. So im hoping someone has some different products that may do a better job of sealing the large creases and filling the large voids than what i am currently using. The dragon is going to have extreme versions of all of these problems. Im probably going to start on the dragon master this weekend, so fingers crossed.

    Probably worth noting a few other things just for reference. The paper i am using is Canson Mi-Tientes which is a mid weigh water color paper (160 gsm). So the paper does have enough structure to support the silicone and does not seem to have any absorption issues with the silicone. I usually have a coat of acrylic on it before i fold it for some origami technical reasons. So the actual origami is quite rigid and i most closely like to paper mâché

    Here is a quick side close up of my lion face master that shows the filler. It shows what is working well and what is not. The sculpy is doing a decent job of filling the voids, and i like the way it sands, but you can sees spots where the baked clay has pulled away from the paper creating some cracks (i have been super gluing the baked sculpy to the paper to try and ill those cracks)
  6. xenobiologist RPF Premium Member Leigh's Avatar
    Member Since
    Jul 2011
    Cambs, UK
    1 Week Ago  Feb 15, 2018, 2:48 AM - Re: Sealing a Paper Master For Molding? #6

    How about Monster clay. Heated so its pourable. It could be poured into the piece & allowed to set in layers until the piece is full. There should be minimal distortion & it should fill all the folds. Where it pours out of the gaps it could be scraped off of the outside prior to moulding. It could also be used to fill the gaps on the outside. I don't know if it would soak into the paper? might want to seal the paper first with a clear coat?

    Just a thought... HTH
  7. Contec's Avatar
    Member Since
    Jun 2008
    1 Week Ago  Feb 15, 2018, 4:49 AM - Re: Sealing a Paper Master For Molding? #7

    Have you tried to have superglue slowly be absorbed by the paper? It would stiffen it. at least it does on ordinary thicker printer paper.
    You say that you use Super sculpey to fill the voids, but have you tried two part Apoxie Sculpt instead. It has less of a shrinking than sculpey and you do not need to bake it. It is quite easy to get into tiny cracks by using a little water to make it softer.
  8. 1 Week Ago  Feb 15, 2018, 4:24 PM - Re: Sealing a Paper Master For Molding? #8

    Thanks gents, this is exactly the kind of ideas i was hoping for. i have not seriously considered magic sculpt or monster clay and both may be better choices than super sculpy. I have actually had both in my amazon cart forever for some other possible projects and i am just going to pull the trigger. I knew that monster clay softens a lot when heated, but did not know it is actually pour-able. That is great info.

    In my tests so far i have been fine on absorption of material into my paper. It is partially water soluble (i actually fold it while it is wet and let it dry to stiffen it), but it takes something really wet to saturate the paper enough to cause problems. I am going to have to do a small scale test on monster clay. I have done 3 "Cold Cast Origami" tests (duck, flying pig, and lion) so far building up my skills to tackle the dragon. Duck took 3 tries, this flying pig took two tries at the masters and molds, the lion i actually got 2 of the 3 parts right the first time. I dont think ill ever get to one and done, but i do so hate wasting silicone.

    Flying Pig Cold Cast Origami
    Last edited by maddoghoek100; 1 Week Ago at 4:33 PM.
  9. Contec's Avatar
    Member Since
    Jun 2008
    1 Week Ago  Feb 15, 2018, 6:43 PM - Re: Sealing a Paper Master For Molding? #9

    I'm sure someone would like to buy cast of the Blade Runner origami's if you ever made those.
  10. 1 Week Ago  Feb 15, 2018, 9:36 PM - Re: Sealing a Paper Master For Molding? #10

    At the moment I am pretty focused on producing my original origami designs, but I know how popular the BR unicorn is around these parts. I tried to lend a little of my origami skills to one of the discussions on it just to pay it forward a bit.

    I'm not such a huge fan of the vintage model personally, but the cover of that 30th anniversary blade runner is awesome. I believe it was designed by Roman Diaz, who is a hugely talented origami designer. I don't know if he is credited or if they bootlegged his design for the cover, but absolutely possible to fold that from a single sheet of uncut paper.

    Folks have made such nice 3D prints of the unicorn, it is an interesting thought if a cold cast of actual paper is something folks would realy want and if you would go screen accurate or larger.
  11. 4 Days Ago  Feb 18, 2018, 8:54 PM - Re: Sealing a Paper Master For Molding? #11

    refolded and split my master into the pieces i am planning over the weekend. Thanks to the gang here for some materials tips. I am going to wait for the magic sculpt i ordered to arrive this week to bulk out the big voids.Just for the gang here i folded up a blade runner unicorn from my scrap.

  12. udog's Avatar
    Member Since
    Feb 2016
    3 Days Ago  Feb 19, 2018, 5:25 AM - Re: Sealing a Paper Master For Molding? #12

    You could also try paraffin (what candles are made of) to make it firmer, maybe a bit cleaner than molten clay.
  13. 3 Days Ago  Feb 19, 2018, 1:12 PM - Re: Sealing a Paper Master For Molding? #13

    The idea of paraffin does sound intriguing. I may add it to my list of things to try. I'm excited to try the magic sculpt, as it had been in my list. So right now all the deep creases and stacked layers that I know need sealing are glued up with superglue.

    My biggest issue at the moment is just needing to get out if my own head and get to work. I know I am going to spend for ever hemming and hawing over vents and pour spout placement. Just need to fight that urge.

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