Lets make these.
Smooth-On Oomoo 25.
This product does not need to be degassed or weighed, it is mixed by volume.
Making it much more user friendly.
Bad Photos, blame the plastic wrapper that I was trying to photograph. On the second frame the label says no sulfur, your gonna have to trust me on that. I would recommend if possible by a natural colored clay instead of blue or whatever. The color is a pain in the ass to clean out of skin, tools, and clothing.
You have to use sulfur free clay so that it does not mess up your mixed silicon.
Adding vent channels.
The holes in the clay will form registry keys that will help to keep the halves lined up properly.
If you are still with me this far along, then I am going to assume that you can read and have a basic understanding of the MATHs. At this point you need to figure out how much silicon to make. So some basic calculations of volume are going to be needed, along with at least one graduated container. So my two boxes had interior measurements of 6.5 cm 9.5cm x 1.5cm & 6.5 cm 11.25cm x 1.5cm, giving me two volumes 92.625cc & 110cc. Total volume needed approximately 202.3cc minus the filler(scroll down) and volume of the original to be cast.
This is America here but metric is so much better for things like this (everything really).
Two Compounds One Cup.
Mix it up.
Follow the manufacturers instructions on mixing the A&B sides of the silicon. I keep two labeled large paint stir sticks like from Lowe's and two measuring cups one for each bucket with my gear. After stirring I add the thinner of the two to the cup up to the first mark, then add the other side up to the second mark.
Stir with a third stick until the color is even, you need to stir this and pour the silicon in around 5 or so minutes you have a work time of 15 minutes total.
Left over silicon.
Keep and failed molds and left overs for this reason.
In this photo you can see the air bubbles caused by mixing and pouring rising up and popping leave them alone and let the silicon do its thing. Gently shaking, tapping, or even vibrating the mold will make this go faster.
(You can buy a professional vibrator for this, please post pics of it delivered to your door step if you do.)
The manufacturer says 75 minutes to cure, I recommend pouring the first half and between 2-4 hours. Let it really set up and cure well before the next steps.
Remove the walls.
Remove the clay
Make sure to get all the little flecks and pieces. Try not to remove the master from the mold silicon.
Prep for 2nd pour
mold release agent to all of the silicon, be extra careful not to get any on the master being copied. Use a old paint brush for this.
Ready to pour the other side.
Rebuild the mold box, mix & pour your silicon.
2-4 hours later.
Give the mold at least 8 more hours to fully cure before you start pouring resin in it, yeah the manufacturer says its ready but do your self a favor and wait.