You Must have missed this tutorial i posted.
24.63.3.23/gfsales/TUTORI...TORIAL.rtf
Pictures to go along with the tutorial are here
24.63.3.23/gfsales/Sculpt...%20sculpt/
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Silicone Caulking Tubes Mold
How to Mold a Bio Helmet Sculpture.
(REFER TO PICTURES IN THIS LINKED FOLDER FOR REFERENCE)
1. Gather Materials.
        1. 7-10 tubes of SILVER brand GE 100% silicone Caulking. (avail Home Depot)       
        2. One roll of Plasterers seam tape. (mesh tape for drywall seam reinforcement)
        3. Can of Clear Coat - Kyrlon
        4. Water Spray Bottle
        5. Latex gloves
2. Prepare the Sculpt.
Ok Take the can of krylon and seal the clay. Most clays have sulphur in them and sulphur as far as i can remember reacts badly with silicone and will cause it NOT to dry. SO seal it up good with a couple coats.
OK! Now that the sculpt is dry and sealed u will begin to cover it with silicone.
3. Molding the sculpture.
With your sculpture mounted on a stand such as this it allows it to stay upright and you can spin it around as you work. I recommend making urself one.
Step 1. Take a tube of silicone and insert it into the caulking gun. Cut off the tip very close to the body of the tube so u have a wide opening. Puncture the seal inside the tubes stem. And start squeezing the silicone out onto the sculpture.
There is no real trick to this. Just squeeze out a large amount onto the sculpt and with your latex gloves on begin the spread it around. making sure u dont capture any air bubbles. this is the detail coat of the sculpture so dont worry about making it thick. just make sure u cover the surface evenly and dont miss any spots.
This is a picture of the sculpt after a couple layers.
Once the detail coat is done you will now want to wait for it to dry. I took a water bottle and sprayed down the silicone to speed up the drying process. Silicone drys because of a reaction with water in the air. So by leeping it sprayed down with a water bottle it made it dry SOO Much quicker.
OK NOW! Repeat the steps you did with applying the silicone except this time GO TO TOWN! Just squirt out all kinds of silicone and build it up but dont do more than a quarter inch thickness otherwise it won't dry!!
Do a quarter inch all around and then spray it down and leave it for a day. When i did this sculpt i would periodically come in throughout the day and spray it down when it dried out.
NOW! Take your plasterers seaming tape and cut some strips of it like 1 foot long. And take ur silicone gun and squirt on a thin layer of silicone. Now press the tape into the silicone and cover the entire surface of the mold with it. THis will reinforce the silicone and keep it from tearing. this silicone that comes in the tubes is not very strong so u need to reinforce it.
Pay close attention to the eyes and the outter areas of the mold.
Once its all covered take the gun and put on a quarter inch thickness all over it.
And once again spray it with the water bottle periodically.
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Final thoughts:
However thick u want it is up to you. I only did a few castings out of this mold. So i didnt make it too thick.
Also the type of silicone u wish to use is up to you. I prefered the Silver TUbes of caulking as pictured. U can experiment with whatever u like its up to you.
The molding process took about a week. I know its a long time and very repitituos. BUT when u compare the price differences there is no comparison. THis is the cheap poor mans way to go.
7-10 tubes of caulking costs about....28-40 bucks. While a gallon of rtv is like almost 100.00.
So if u want a cheap way to make a mold that u wont be mass-producing castings from. This is the way to go.
Enjoy!
MEanGene the Dancing Machine