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135
Mold Making and Resin Casting

Once this has set for 4 hours, you can now break down the mold box to begin the process of pouring the other side. Once the sides are removed, put them to the side, as we will re-use them for the second pour. Turn your half poured piece over and set it back on the same base (Fig 20). Start removing the clay bed. The clay bed will come off fairly easy.

You will find that you still have some clay bits adhering to your proto type. Use your flat scraping tool to gently remove the bigger pieces and a toothpick to remove bits from any detail (Fig 21).

Now, as before, use your brush dipped in alcohol to dissolve the remaining clay bits and residue right down to the silicone seal at the prototype. Be careful not to pull on the prototype itself, thus breaking the seal or you will have silicone from the second pour run down the seam where we don't want it.

Now rebuild your mold box in the same manner as before. Next, use a brush dipped in petroleum jelly and liberally apply it to the surface of the cured silicone (Fig 22). This is very important. Silicone bonds to itself and without this barrier, your part will be locked into a cube of silicone.

Try to be careful about getting Vaseline on your prototype. It won't hurt anything but can fill in fine detail so wipe any excess off with a clean brush.

We are now ready for the second pour. Mix silicone as described before and pour. In 4 more hours, we can begin making duplicates of our master.

After the second pour has cured, break down your mold box. Gently separate the 2 halves of the mold (Fig 23). They should come apart pretty easy here but you may have to coax it a bit.

Now remove your prototype.
  • fig20
  • fig211
  • fig22
  • fig23

About the Author

About Steve Sherman (bowjunkie35)
FROM: IOWA, UNITED STATES

Steve is a freelance propmaker (the movie kind) and machinist. A former construction worker, he has been working with tools since childhood. He learned the construction/ metal fabrication business from his Father, so to follow in Dads footsteps was natural. Since leaving the construction industry, h...


Comments

Good informative article, very interesting. I've often considered making my own castings but have been deterred by the cost and lack of advice- at least one of those hurdles has now been addressed!
JAN 03, 2005 - 07:24 AM
Informative article, thanks, now maybe I can get rid of those lousy rubber/vinyl tires...... :-) :-) :-) :-)
JAN 03, 2005 - 08:23 AM
Yep, that is what I do also. It's in the article! Thanks Again guys for the compliments. LogansDad, I also use the 10:1 ratio RTV as it is more economical but much harder to use especially for someone just starting out. I used the 1:1 ratio RTV for the artivle for simplicities sake.
JAN 03, 2005 - 08:24 AM
Great article, Steve. I recently made my first attempts at molds and casting, and it seems like fun. Your info will help a lot. Thanks for all your hard work!
JAN 03, 2005 - 01:21 PM
I was trying to use the micro - mark info but it wasn't as awsome as yours. Now I might be able to do some stuff without ruining it., or waste money to just buy one part from a figure set. Thanks for the info. Happy Modeling
JAN 03, 2005 - 04:34 PM
Well thanks a million for sharing all these nice info with us . U really capture the whole procedure in a very good way amd very simpe to follow. Now i just have to come over there and get all the materials , rubber silicone and resin ...... Super nice article Costas
JAN 03, 2005 - 08:04 PM
hi Steve, thanks so much for the great article and very good photos. I felt reading a chapter of a modelling book more than a feature.it was very very helpful. congrats
JAN 03, 2005 - 11:40 PM
Just in time. I'm actually casting a couple of alice packs and German ww2 bergens.
JAN 05, 2005 - 01:25 AM
Wow!! You all are far too kind! It was really my pleasure, but the positive feedback is great. I am getting misty eyed! *tear* :-) :-) Again, Thanks for the comments, they do not go un-noticed!
JAN 05, 2005 - 03:43 AM
it's been said,but still...great info, very well presented, nice tone, am excoted about casting! Thank You!
APR 03, 2008 - 11:28 PM