Octopus sculpture

Discussion in 'Lost wax casting' started by Zapins, Dec 18, 2018.

  1. Jason

    Jason Gold

    I'm a cheap ass and run the same walmart fiberglass resin. Yup, stinks the entire house up.. and I did it in the garage. The booty butter does work better than just mold ease200.
    Every time I run a mold, I swear up and down, I'm going to try that plastipaste stuff.... Then I see the price. https://www.smooth-on.com/products/plasti-paste-ii/

    I just want to know how far this stuff actually goes? I could see me spreading on a 100bucks worth of PP for a mothermold.:(
    The recent tree I did was actually cheap to make. I had about 30bucks of resin and glass. If PoP wasn't so damn soupy, I'd use it. It's cheap and I'm not pulling a large amount of pieces anyways... It's the extra time it takes to wall up the damn thing AGAIN!:mad:
     
  2. Zapins

    Zapins Gold

    Man maybe I'm doing something wrong but 1 gallon of that bondo resin stuff costs 50 bucks and I needed 2 of them for the tentacle & octo head and that's not even counting the fiberglass cloth. Then 3 of the silicone rubber tubs (35/each) and I've got a tidy sum invested in this mold. Would be nice to have only spent 30 like you on the shell. Not sure how you got away with that.
     
  3. Jason

    Jason Gold

    You drowning your stuff in resin??? I mix up a cup, paint the silicone, lay on some glass and stipple to get the stuff to penetrate the fibers. I might brush a little more as I lay another layer. I apply 3 layers of glass for the most part. No need to soak the ever living piss outta this stuff. It would take 2 days to dry, if it ever does. My stuff is dry in 8hrs. If your stuff is taking longer, you probably are using too much resin. My dad was the pro with this stuff, he was a boat builder and fellow cheap ass like me. Must be genetic. All Massholes are cut from the same cloth I guess.:D:eek:;)
     
  4. DavidF

    DavidF Administrator Staff Member Banner Member

    WTF are you talking about?? Catalyzed resins are exothermic, the thicker/ more resin you use as well as adding fillers increase the temperature during the cure and cause it to kick faster. This is assuming that your not working inside an ice box (or did not use enough catalyst) in which case you would need to increase the promoter (cobalt napthane) and the catalyst (mek) if using a vinylester resisn you can add dimethelyene sp? and kick the stuff off rock hard in less then 10 seconds.
     
  5. Zapins

    Zapins Gold

    Yeah it dries hard in about 1.5 to 2 hrs the way I'm doing it. Can you film how you do your resin the next time you use it? And are you using the nice tightly woven cloth fiberglass or the loose coarse stuff? I'm using the coarse stuff and it falls apart and frays when brushed. So I've been laying the cloth on the surface of the resin and then turning it over and laying it on the resin. It pulls up a lot of resin that way and quite a bit flows off onto the cardboard.
     
  6. DavidF

    DavidF Administrator Staff Member Banner Member

    Get yourself a sheet of polypropylene, cut your mat to the size you want then using a roller wet the surface of the polypro, place one layer of mat down and roll across the top of it forcing the resin in, add the next layer and repeat, repeat, repeat until you have built up to the desired thickness. Then wet the surface of your silicone slightly and transfer your glass/resin laminate to it and using a cut down chip brush work out the air bubbles....
     
  7. Zapins

    Zapins Gold

    Polypropylene sticks to resin the same as fiberglass? It looks like plastic.

    Do you use a paint tray to apply the resin with the roller?

    The way I do it seems to work ok but I know it definitely uses way too much resin and there are lots of bubbles. It basically leaves a lot to be desired in the looks department and its kind of expensive. But from what I've read you need 1/4" of shell to make a good support and applying that many layers of fiberglass seems like it might be a PITA if done with thinner applications? Besides wouldn't I need the same amount of resin in the end anyway? I don't know what do you think?
     
  8. DavidF

    DavidF Administrator Staff Member Banner Member

    The resin will not stick to the polypro, just let the leftovers kick off on it, flex the sheet, and it will pop right off.... The idea is to build up the laminate to the desired thickness on the sheet of polypro, then transfer it to your silicone molded part.. You can roll out the air bubbles in the laminate while on the poly sheet.
    Nah, just dunk a 3" roller into a qt cup...or pour some out onto the poly sheet and spread it with the roller....
    You can get away with way thinner....
    No your over saturating your mat, should only be using about a pint for what you have...
     
  9. Jason

    Jason Gold

    I just follow the directions, run thin layers and it works. I weigh the stuff out with my drug dealers gram scale. yeah, I'm kinda anal like that.
     
  10. DavidF

    DavidF Administrator Staff Member Banner Member

    ?? anal for drugs??:confused: You should seek help... ;):D:p
     
  11. Jason

    Jason Gold

    :rolleyes:

    Zap I use both the woven and chopped mat. I like the woven for my first layer and then back it up with chopped to fatten it up. I doubt it really matters with the kind of crap we do.
    I always cut pieces ahead of time. I've seen some guys use a paint roller tray with resin in it and soak the pieces and apply them that way. I work kinda slow, so I'd F that up quickly.
    Here is a page on the versions and their proper uses... https://www.fiberglasswarehouse.com/chopped-strand-mat-choosing-fiberglass/
    Stay FAR away from epoxy resins when running this stuff, it screws with chopped mat.
     
  12. crazybillybob

    crazybillybob Silver Banner Member

    With the chop mat do a stippling action with the brush not painting. You just need the resin to soak through the mat. mat takes a little more resin than cloth but not that much more. It's been awhile since I have done anything big with fiberglass, last one was a snake model that all said and done was a little bigger than a human head. I think it has 2 layer of chop and 2 layers of cloth (first and last) I think i had 2 cups of resin (was doing it in epoxy) and about 1/2 a cup was on me, the workbench, floor, in the cups, the ceiling.....the cat all the normal places one would expect it to be :rolleyes:.
    Here's a pretty good article on making a mother mold over silicone. https://www.tested.com/art/makers/460463-zoidberg-project-part-9-all-about-molding/ This one is not as good https://www.tested.com/art/makers/455335-volpin-project-part-8-more-complex-moldmaking/
     
  13. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    It would only be a factor at all if he was using mat versus of cloth. Even then the issue is the binder in the mat and whether it is activated by the resin and how readily it conforms. Contrary to the claim in your link, universally compatible mat is commonly available but it probably wouldn't make a hill of beans difference in this case anyway depending upon the size of the pieces of mat being hand laid.

    Zap, occasional exposure to the resins you're using isn't much of a concern, but if you can smell it in your house for several days, you're exposed and it isn't occasional, it's prolonged. Might want to take a look at the aromatic ingredients and use that medical education on that one. Among the many, MEK is some nasty stuff.

    There are a lot of similarities in art mold and foundry pattern building. The least expensive and probably the fastest way to make the backer is PoP. In the days gone by, pattern makers used hemp as fiber reinforcement for the PoP and you'd be surprised how strong that is. It would be <$10 material for this project. Just make a box, mix with a paddle on a drill and pour. But, it's heavy to use and store. If it's just one or a couple shots, pitch it and save the silicone for the future. Easy enough to make the backer again if ever needed in the future.

    The best advice for price on resins and fabric is don't buy at Walmart. Buy fabric by the yard online. -Lot's of choices there. For odor control, epoxy, urethanes, Poly/Vinyl Ester resin best to worst. Price goes the opposite direction but low cost epoxy laminating resins can be had for ~ $50/gal and polyesters really aren't much cheaper unless you're buying 55gallon drums.

    I would think chopped fiber reinforced urethane pastes would be great for this application. It's about $85/gallon and a gallon would probably be ample for this project at less than half the total cost. Just trowel it on and fine tune it by hand with latex gloves. 90 Minute demold time. No glass cloth needed because it's already in the paste. One coat that you can apply it exactly how/where you need it.....done. You can estimate quantity required by volume of your mold, and the link says 1/2" recommended thickness, but from having used it, if you had even a 1/4" coverage it would be very strong for what you are doing.

    https://www.freemansupply.com/produ...freeman-1030-polyurethane-reinforcement-paste

    Best,
    Kelly
     
  14. Jason

    Jason Gold

    That's a good reference billybob. Thanks for posting it, but damn that thing is ugly!
     
  15. PatJ

    PatJ Silver

    Cool stuff.
    It will be interesting to see this piece cast.

    .
     
  16. Zapins

    Zapins Gold

    Thanks for the info and links. Maybe next mold I'll get the other stuff and try it out.

    I finished the mold. It still is itchy af to touch, so maybe I'll wash it off to get rid of stray fibers.

    It always makes me a bit sad to have the original piece break into a million bits when demolding for the first time...

    Here is what I have. I'll pour some test pieces tomorrow. I wonder if the tip of the tentacle will cast without special attention and a brush?

    20190516_233720.jpg 20190516_233643.jpg 20190516_233657.jpg 20190516_213656.jpg
     
  17. Jason

    Jason Gold

    If your original wax model came out like that... How do you expect the next one to behave?? Got some kind of miracle wax like that red stuff Dave rants on about?

    Molds look good. fingers crossed
     
  18. crazybillybob

    crazybillybob Silver Banner Member

    If it doesn't work as a steering wheel. You and Jason can team up and sell some nice adult toys together :rolleyes::p
     
  19. Zapins

    Zapins Gold

    We'd have a captive market in Japan I'm sure.

    The tentacle broke because the first time the mold is opened the silicone is stuck together hard and is stuck into the resin shell. So it needs to be pulled and bent to remove it. Once it was freed up it slides in and out easily, so castings will be easy to remove intact. I have a video of the demolding part which I'll edit at some point an post.
     
  20. DavidF

    DavidF Administrator Staff Member Banner Member

    Im curious to see how well the tentacle mold fills. Hopefully not entrapping lots of air pockets.
     

Share This Page