Here's a new idea I came up with for molding my underarmor. I used 1/8th inch thick craft foam to create a master, then used silicone caulking to make a mold. I used some cheap silicone that I found at Busy Beaver for two dollars a tube. Most of the other stuff I already had (except the foam) so the whole project only cost about 17 bucks so far. I haven't decided what material I will cast the parts with, but I am very pleased wit the mold. Anyway, here's what I used and how I did it.
Templates in various formats are available at the bottom of this post.
Materials:
(15 sheets) 9 x 12 craft foam (foamies)
Paper
Card stock
(4 tubes) 100% silicone, Clear (not white)
*EDITED 05-03-09
[Do Not Use GE Silicone II. I recently used it to mold some rock climbing handholds for my son and the silicone never really cured. Two brands that I know work are White Lightning 100% silicone and DAP 100% silicone.
(About 1/4 cup) laundry bleach
(1 teaspoon) colored marking chalk
(1) disposable paint brush (bristle type, not the foam ones)
Glue for the foam. (I started with hot glue but wasn't happy with the results. After researching on the internet a little bit, I tried regular Elmers, which worked great until I tried to bend or curve the piece. For my next attempt I will be using spray adhesive )
Tools:
Respirator & safety goggles
Hobby knife
Ruler
Something non-porus to mix your silicone on
1 1\2" or 2" putty knife
Caulking gun
Ball point pen
I started with a reference picture of the lower back.
Then using Visio, I created a template for the piece.
This picture shows the template with numbers in each area. The numbers show how many sheets you laminate together in each section to create the details.
Using my completed FS HD torso and the reference pics I came up with a printed size of about 19 3/4" wide by 12" high. Keep in mind some of the underarmor is covered by the torso and the cod piece. To check the scaling I printed it on some regular paper, taped the sheets together and test fit it with my torso. Trial and error wil get you where you need to be. Once you have the right size print the template on some card stock.
The next step was to create the master using the template. I started with 3 sheets of foam laid out side by side to create a mat 12" high by 27" wide. This mat will be the base layer.
Cut the patterns out of the card stock and lay them on your craft foam. Using a ball point pen, trace around each shape.
(gotta be a ballpoint or your foam will tear) I cut out each layer individually, but I think I could have gotten better results if I laminated the foam together with some spray adhesive before I cut them out.
For the quilted area in the center, you will notice the dotted lines on the pattern. Transfer the dotted lines onto the foam with your ball point pen. You will have to score the foam here to create the quilted look. I used the handle of my scissors for the scoring and found that by first wetting the scissors and then rubbing them very hard across the lines It produced a nice effect without tearing the foam.
By
joeycoz at 2009-03-08
By
joeycoz at 2009-03-08
Once all your parts are cut and scored you can start laminating them to your base sheet using the pic below as a reference. Where you see a number 0, this will be your base sheet. The rest of the numbers show how many layers are laminated together to produce raised details or reliefs. Be sure when you start gluing, that you apply glue all the way to the edge of each piece of foam. If not, the silicone will get between the layers and will ceate imperfections in your mold.
Here's some pics of my completed foam master
Now for the mold!
Lay your master down on a nice flat work area.
Next you want to sart with a very thin layer of clear silicone over your entire master. This first layer should be no thicker than 1/8 of an inch thick, otherwise it may take a week or more to cure. I used a caulking gun to apply ithe silicone,
then used a cheap bristle paintbrush to spread it around and to fill all the nooks & crannies. Check the entire mold for missed spots or thick areas. If the clear silicone looks white in an area, then you have it too thick. Let the first layer cure for 24 hrs.
Here's a pic of the master with the first coat.
Silicone caulk usually needs air to cure, so you cannot use it to create a mold unless you very carefully built your mold in very thin layers with long cure times in between. But by mixing a catalyst with the silicone you can demold after 40 minutes to an hour. The downside to this, is that by mixing in the catalyst you also trap lots of tiny air bubbles in the silicone which will create imperfections in the surface of the mold. By applying a very thin layer first, the surface of the mold will be as good as the surface of your master. Small air bubbles in subsequent layers won't matter. So what can you add to silicone caulk to make it cure so quickly?
Normal household bleach. Add 50-60 drops of bleach to each 10.1 oz tube of silicone.
Now you can start thickening up your mold.
Start by measuring out the bleach into a small container. Although it's not nessasary, you can add about 1/8th of a teaspoon of marking chalk to your bleach.
This will help you see whether or not you are mixing properly, just keep stirring until the mix is a nice even color (I figured this out on my last batch).
I don't know if silicone fumes are bad for your lungs or eyes, but you should put on your safety gear now just in case.
Empty a tube of silicone onto your mixing board in a circular pattern leaving a "well" in the middle of the silicone.
Dump your bleach/chalk mixture into the "well"
Use your putty knife to mix the bleach into the silicone. You will feel the silicone get a little stiffer while mixing, but keep mixing until you have a nice even color.
Next start layering the mixture onto your mold with the putty knife. Try not to trap any large air bubbles in the silicone while layering your mold. I mixed one tube at a time and used a total of four tubes in this step to creat a mold that was about 1/2 to 3/4 of an inch thick. The working time of the mixture was about 10 - 15 minutes and I let each layer cure until it was firm to the touch (about 15-20 minutes)
1st application
2nd application
3rd application
4th application
Let the mold cure for about 40 minutes or so
The last step is to remove the mold from the master.
I had to do a little cleanup on my mold with a hobby knife after removing the master because silicone had gotten between the layers of foam . I think that by using spray adhesive as opposed to Elmers glue would prevent this.
Flipped over & removed base sheet:
Pointing at a problem area:
Cutting at the defect:
Once cut, Just pull away:
Anyway, here's some pics of the finished mold.
Let me know what you think, and if you try this out, post some pics!
Here's the templates
Great Job! 
