Collect. Kitbash. Customize. Community. Showcasing the Best of Sixth Scale Modeling.

Page 2 of 2 FirstFirst 12
Results 31 to 38 of 38

Thread: How to make a mold and cast

  1. #31
    Join Date
    Apr 2009
    Location
    Ape City
    Posts
    861

    Re: How to make a mold and cast

    I was just re-reading this and made minor corrections--I mixed up pressure pot and vacuum chamber, which are two totally different beasts. Hopefully that didn't mess up anyone. My apologies.

    Searching through the internet, I found this, which explains it in terms I can easily understand and retain.

    Vacuum casting actually removes bubbles and air from your RTV, before you pour.. so you're bubble free in the mold. What pressure casting does it make the bubbles SO small they essentially disappear. some guys vacuum the rtv and pressurize the resin. there are many schools of thought on the topic, and most of them DO work. you have to pick what you can afford, and what works best for you.
    Last edited by jessica; 06-06-2011 at 13:01.

    We chimpanzees are too few. How can we take the iniative when THEY are in control?

  2. #32
    Join Date
    Jul 2010
    Posts
    401

    Re: How to make a mold and cast

    The way you cast the halves separately before bonding them with more resin is really quite genius. It should theoretically solve the issues I've had.
    However, I'm curious about that. Will a fresh mix of liquid resin really bond to cured resin? Certainly you're using a type that works; but I'm skeptical of my products. I've used plastic toys with firm bases as levelers (the way you use clay), and the resin often gets everywhere. After it's cured, I am able to peel the resin off of the plastic toys - meaning it didn't bond. Perhaps that's all due to the fact resin won't bond to real plastic, whereas it reinvigorates cured resin just enough to bond to it. Maybe? I'm stabbing at the dark here.

  3. #33
    Join Date
    Apr 2009
    Location
    Ape City
    Posts
    861

    Re: How to make a mold and cast

    I just tried to twist apart one of my Julius casts. It's impossible to twist it apart. In fact, I even stood on it (without shoes of course but only for a couple of seconds cause it hurt), and the resin cast did not split apart. Resin had no trouble bonding to itself. Don't know why that is.

    We chimpanzees are too few. How can we take the iniative when THEY are in control?

  4. #34
    Join Date
    Aug 2004
    Location
    Our Nation's Capital
    Posts
    503

    Re: How to make a mold and cast

    Different brands of resin might not bond to each other, but I've had no problems adding new Smooth On 300 (or 325) to the same kind of cured resin even when the cured resin is several weeks old.

    Whenever I pour resin, I always have more than one mold on hand: the primary mold for the main cast I'm trying to make and then at least one extra mold to use up any extra resin so I don't waste it. The extra mold usually doesn't get filled up the first time so each time I add to it, the original resin has cured . It can take two or three or four goes to finish the pour, and when I finally take it out, it is completely indistinguishable from a cast made from a single pour of resin. The only time you can see anything is when I'm using the 325 with tint in it and then the variations in the tint will show up as different shades, but even then the piece is still completely solid.

  5. #35
    Join Date
    Apr 2009
    Location
    Ape City
    Posts
    861

    Re: How to make a mold and cast

    I do that, too! Sometimes half of the mold will get two or three layers of resin, and it could be weeks before I get that second or third layer of resin into the mold. Once I had a translucent resin layer underneath white resin, by two different companies, and the resin was able to attach between layers with no problem.

    We chimpanzees are too few. How can we take the iniative when THEY are in control?

  6. #36
    Join Date
    Jul 2010
    Posts
    401

    Re: How to make a mold and cast

    I just tried it yesterday. The liquid resin bonded to the cured resin as if it was all one mix. Pretty surprised.

  7. #37
    Join Date
    Apr 2009
    Location
    Ape City
    Posts
    861

    Re: How to make a mold and cast

    I tried rotocasting using the same materials I have been using. liquid resin was a slower cure of about 6 minutes instead of 3. The only difference was I used baby powder on my mold before I poured in the resin, which I think helped minimize surface bubbles. The only thing was the neck was hollow. I punched a hole, poured some more liquid resin in there, plugged it up with clay, and stood it up like normal... and it's now curing. The curing resin's heat created some pressure inside the rotocast, and found its way through a weak spot and started slowly seeping out. What I did was punch a hole in one of the ears to let pressure escape. I'll post photos when I can.

    We chimpanzees are too few. How can we take the iniative when THEY are in control?

  8. #38
    Join Date
    Apr 2009
    Location
    Ape City
    Posts
    861

    Re: How to make a mold and cast

    For the casting material I used this:


    My two part mold was secured with plastic wrap. After pouring the resin, I wrapped more plastic wrap around the mold to ensure that no plastic would leak out of the pour hole. For my spinner, I used my right arm. When I got tired, I used my left arm. I basically just kept rolling around the mold until I felt it had set. The resin is a slower cure resin, so I had about 6 minutes before it set. There is a faster resin, a 3-minute one, but I feel too pressured and end up with way too many air bubbles for my liking when I use that.


    Because my cast was hollow, I opened up another pour hole in the bottom of the neck, poured more liquid resin and capped it off with clay and stood it up to let it set. Pressure/heat was created at this stage, so the liquid resin leached out of a weak spot. I caught this in time so wiped off the liquid resin, and created another escape hole in the ear of the cast. I put additional resin in there so that customizers can drill up into the neck and find solid plastic. I don't think I would have had enough time to catch this if I had used a faster setting resin.



    Comparison shot of solid cast to the left and hollow cast to the right:

    We chimpanzees are too few. How can we take the iniative when THEY are in control?

Similar Threads

  1. Is making a soft, flexible cast possible?
    By justinluck in forum Sixth Scale Action Figure News, Reviews, & Discussion.
    Replies: 8
    Last Post: 12-20-2008, 00:50
  2. A word about grammar.
    By furious genius in forum Loose Bits (Off Topic)
    Replies: 29
    Last Post: 01-29-2008, 22:33
  3. Tutorial: Enlarging a Head Sculpt
    By KillingYouGuy in forum Sixth Scale Action Figure News, Reviews, & Discussion.
    Replies: 4
    Last Post: 09-11-2007, 08:55

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
How to make a mold and cast
How to make a mold and cast
KGHobby...Click Here!
Urban Samurai Hobbies...Click Here!
Timewalker Toys...Click Here!
BlackOps Toys...Click Here!
HobbyLink Japan...Click Here!
Cotswold Collectibles...Click Here!
The ToySource...Click Here!
Big Bad Toy Store...Click Here!
Brian's Toys...Click Here!
ToyWiz...Click Here!
Nouveau Toys...Click Here!
ToyWiz...Click Here!
Gremln...Click Here!
Hot Toys...Click Here!