Table of Material Properties and Observations of Silicone

Silicone	Color	Work Time (hrs)	Cure Time (hrs/days)	Shore Hardness	Mixing Ratios (by weight)	Application Observations
RTV-627		2 hrs	2 days (workable after 24 hrs)	62A	1:1	Sticks decently to skin. some slipping occurs, hardness makes it a bit uncomfortable on the skin. When cured exposed air, has a glossy surface, tears fairly easily, not very elastic
RTV-31		2 hrs	24 hrs	54A	25 drops DTDC to 100 g RTV	Most brittle of the silicones. Does not stretch skin well, very slippery and glossy.
RTV-615		4 hrs	6-7 days (workable after 24 hrs)	44A	10:1	Needs de-gassing, but tends to overflow (container needs to be quite large). Has decent adhesion to apply skin stretch. Should not be cured in completely open space due to dust falling into the silicone while curing
Tap-RTV		25-30 min	6-8 hrs	25A	10:1	Stretches skin well, softness is good for the skin, cures easily and pours easily
SR-1618		25-30 min	24 hrs (workable after 12 hrs)	15A	10:1	Stretches skin decently, a little bit softer than the blue silicone, no mixing problems
SR-1610		25-30 min	24 hrs (workable after 12 hrs)	10A	10:1	Very soft, almost skin-like. Doesn't stretch skin very well, too soft and compliant

This is the more compact end-effector I made, using SDM processes to make the oval shaped, silicone pieces, as well as the main structure.

I noticed that how well the end effector contacts the arm/skin area is extremely important (obviously). The flat surface of the silicone should be completely in contact with the skin, evenly, in order to reduce the amount of slipping. To test this out, I created some end effectors with sloped contact points, as seen below. It worked better, and required less normal force, but again, this was just a test piece. To really have the contact surface be normal to the skin, the entire skin stretching device should have the ability to rotate to accomodate for the sloped plane of the arms/limbs.