Hi Patrick -
I'll take a shot at this one, as I am a caster and use a fair
amount of 'acrylics'. Hopefully, Doug will also add in the
conversation.
There are chemical and reactive differences between epoxy and
acrylic, but I think for the challenge either could be considered
as the 'second medium' which I believe was the goal Doug was
trying to get to, so my vote would be 'it doesn't matter'.
Lot's of folks use products from Alumilite - like me. Alumilite
resin comes in different chemical formats, so just saying
something is 'made from Alumilite' is a misnomer. Alumilite makes
casting epoxy and also acrylic products and they work differently,
but in the end, I believe both meet the 'second medium'
qualifications of the challenge. Other products like Total Boat,
Silmar, MAS, PUR and lots of others are also in the market, each
offering somewhat different hardness's, color mixing qualities, or
UV stability.
Alumilite Clear Cast is a two part casting epoxy. Alumilite Clear
Slow is a urethane resin, also two part, that is widely used by
pen turners, including me. Lots of people call this an 'acrylic'
resin, but chemically it is not. Turning a true 'acrylic resin
blank' is a test of your patience - as they tend to be brittle,
very chippy, and tough to work, but due to their hardness they
polish up really nice! Acrylester is a typical 'generic' name for
acrylic blanks.
I don't use the Clear Cast, as I find it too hard to work - it is
really made to be a casting or a finish and doesn't like to be
turned. It also is more difficult to get dependable color
combinations out of as the setting time is a little long for my
liking.
Alumilite Clear Slow on the other hand is a much softer material,
works easier, and is pretty easy to get interesting color patterns
with by mixing at different times in its curing process. Both
products cure out to be a hard material that holds up pretty well
over time.
The bigger issue is if you need a pressure pot or not to get a
good casting without air bubbles. Epoxy often allows you to gently
use a blow torch along the surface to drive out the air bubbles
and get a good casting. Most people do not use a pressure pot for
epoxy pours, they simply control the mixing of the components and
use some heat to clear out the bubbles. Epoxy products have a lot
of different working times, but generally epoxy takes a good while
to set up - at least 30 minutes or more.
Alumilite Clear Slow must be cast in a pressure pot at about
40-50 lbs of pressure for roughly 4-6 hours to insure no air
bubbles remain in the casting. Clear Slow is a heat curing resin
and it gets really hot as it cures, taking about 15 minutes of
'working time' before it must be in a pressure pot where it then
takes some time to cure.
I don't know if I have answered your question fully, but feel
free to ask more!
Kevin
On 5/15/2024 12:17 PM, Monthly Club
Challenge Information & Discussions wrote: