I have read a bunch of different product and personal pages now on casting
resin based on the recommendations of those in the other thread. I decided
it was time to start a new topic since it has changed slightly.

I'm actually intrigued with the process now. I have artistic ideas bouncing
around inside my skull and I have the urge to try some of the legal ones.
LOL.

As near as I can tell the the only thing that can form a clear solid of any
dimension in one (sorta) step is acrylic. The problem is it has to be cured
in an "autoclave" for an extended period. Not something practical for most
garage hobbyists, but not totally out of the question.

There are some other "water clear" resins, but the do not fully harden.
They finish with hard rubber hardness similar to that of rubber stamps. The
primary use of these seems to be to embed stuff in vase. Marbles,
artificial flower stems, etc. I suppose that could be handy if you were
making rubber stamps by cutting a mold by hand. I might even buy some just
to play with that. I do have a mini CNC mill setup out in the shop and I
could cut 2D molds for making stamps in minutes depending on my base
material.

It seems like the resins actually used for what I originally wanted to do
are primarily polyesters. Watching some of the videos and reading some of
the pages on it tells me the only advantage they have over epoxy is their
clarity when finished. They are near glass clear. They are a big pain to
cure, and the one video that showed a 3/4" deep pour did it in (4) FOUR
pours. They did a 1/4" pour 3 times and then did a finish pour. This
brings us to its limitations and advantages. There are some things that
polyester resin does not stick to very well. Apparently Mylar,
polypropylene, packaging tape, etc as that's what they used as removable
forming tools. It also does not cure hard and smooth when exposed to air,
and it has a fairly limited working range. Also, the proportions for
working with it will vary, and when doing multiple pours it can be as much
an art as a skill to get the catalyst right when pouring a second or third
layer over gelled previous layer.

The basic thing that led many to start me looking at "casting" resins
instead of using the epoxy I already have is not any better with polyester.
Even those sold as casting resins. The thermal component of the chemical
reaction. I have done 3/16 pours with epoxy with no ill results. I put a
liner in a wood toolbox my son made in shop class this way. Except for the
entombed insects because we forgot to cover it the result looks great.
Epoxy sticks to just about everything, so any mold is most likely to need
some kind of releasing agent. It does not cure perfectly clear, and I am not
sure how you would deal with the thermal component when doing multiple pours
for additional thickness as epoxy is typically mixed 1:1 resin to hardener.

Acrylic is a whole different class requiring a much larger investment.

So, is there a resin that will pour a thick solid in one pour with out
having an unsafe or unsatisfactory thermal reaction, has a hard final
finish, and has a satisfactory hardness with out any more special work or
equipment necessary than epoxy or polyester?

Is the finished solid machineable like epoxy or polyester?

Bob La Londe
www.YumaBassMan.com