I couldn’t agree with Les more. I still get free samples of Silicone
to test and compare. I also started using Silastic E RTV in 1977. I
still have many of these mold and they still work to my satisfaction.
I have stated this several times before but the best Silicone to use
is a little hard to find even though it is in the Silastic group. L
RTV is the best of all I’ve ever used. Here is a list of the Silastic
mold material and their properties. All have virtually no shrinkage
and are contaminated by sulfur and gum rubber contact. Shelf life of
about two to three years. I’ve used some real old stuff and still got
good results. I have also put my vulcavizer in storage.
E RTV - White silicone. Easy to cut but will tear at some fine
detail. Fairly fluid. I don’t recommend it’s use anymore. It was the
first Silicone I ever tried.
L RTV - Light green silicone. The best jewelry mold making silicone
available. Pours, cuts and injects great. My silicone standard to
compare all other silicones to. I guarantee if anyone tries this
silicone they won’t go back to anything else.
J RTV - Light green silicone. Looks just like L RTV. This stuff is
good, but MAAAAAN are these mold hard to cut. Very little flex. Good
for real flat objects.
M RTV - Very similar to J RTV. Blue in color. I like this hard
silicone for metal mold making. It delivers great detail in the class
rings I tool. I just make one seam cut and the mold peels away from
If any of you CAD users want to see this mold process with my class
ring process, I will have a CD Rom Flash presentation done within a
week or two and could send one out. I need postage paid but the CD
will be free. Let me know off line at @T_R_Hawkinson_Ltd1.