- You can affect the set time of the algenate based on
the temperature of the water.
The warmer the water, the quicker it's gonna set.
If you really want to be meticulous, you can do a small test
batch with a candy thermometer to test the temperature
of the water and keep little notes as far as how quickly
things set.
Cleave with this water, about five minutes or so.
Now, if you're doing a life cast, the water would be
colder since we have to work with it.
Since we built a box, this is gonna be poured in,
we wanted it to be a little bit of a quicker set.
But if we were using the algenate for a life cast,
we would need a little more working time so the water
would be colder.
How's the Cleave, need a little more water?
(mumbling)
And sometimes, too, unlike plaster, you can add water
to the mix, you can't do that when you're mixing plaster.
Just spread a nice base.
Can I see your hand please.
I'm rubbing this in to make sure we get all the detail
and limit the amount of surface bubbles you may get.
Okay put your hand in.
Are you comfortable?
When you're casting someone's hand, you always want to have
enough room to do your sculpture.
You have to think ahead that what your creating here
is the foundation for what you're gonna do.
So if a person has curled fingers it's gonna be
hard to sculpt the details so you wan their hand flat
with fingers spread as wide as they can comfortably do
for five minutes.
So we poured a little bit of algenate in the base,
set her hand in.
Go ahead.
And now we're just filling the rest.
I think we're gonna need another batch.
Yeah, it still hasn't started to go yet,
I mean, it's just starting to go on my skin,
just a little bit.
But it should be enough to set against the batch.
That's the other thing with algenate, too,
it's a little temperature sensitive so as you're doing this
you'll notice that in the areas against her skin where
there's warmth, it actually sets up first.
So you can see it's just starting to go right now.
There's another good note, algenate will not stick to
algenate.
Like, wet algenate will not stick to algenate that's
already set.
So we're able to do this because the top layer has not
set yet.
This just just a little thickening bath just to make sure
the mold has enough thickness.
Okay now we just sit and wait for the material to set up.
The next thing we're gonna do is prep to pour the
plaster, the liquid plaster into this mold.
You don't want to wait too long because algenate will
start to shrink as it sets and that'll create all kinds
of problems.
So we want to, once this is, we have Cleave outside
right now actually prepping the plaster so when we pull
her arm out we can take the mold directly out to Cleave
and he can start pouring the plaster where we can
generate our positive off of which Bruce is gonna
do the sculpt.
The algenate has set up and algenate, for those of you
who don't know it's an impression material that's
been around for a while.
Typically dentists will use it if you've ever had
molds made of your teeth, if you have braces.
It's the same material, it's a derivative of seaweed,
doesn't stick to anything.
When it sets, as you can see, it becomes a very
rubbery material.
I mean, this is, not a lot of tear strength,
but this is algenate when it's set.
Takes up all the detail.
We're need it for hand, pore, fingernails, everything.
So this material is now set, we're ready to get her
hand out so alright just start wiggling your fingers.
And then slowly you'll have to break the suction as you
kind of just pull your arm out.
Cynthia is moving her fingers around to release the
suction of the algenate, it might take a minute.
There's never any danger that, "Oh my gosh,
"she's gonna be stuck in here."
Again, if there was a problem and after 20 years I've
never had one, we could always slice this up and pull
her hand out if need be.
- Just let her work her fingers.
Just a matter of, again, releasing her fingers to break
the suction of the material, you should hear a--
- I feel the suction.
- There it is, alright!
Not missing any fingers, not missing any fingernails.
What we have here is negative space that her hand takes up.
And in this negative space we're gonna pour the plaster.
So I guess Cleave is ready to start mixing up the
hydrocal, we're gonna use white hydrocal
which is a very hard white plaster.
It expands slightly and that helps compensate for the
slight shrinkage in the algenate.
So Cleave is getting ready to pour the plaster into
the water.
And again, the first thing you want to do is once you get
your plaster and it all settles you want to fluff it up
so that it gets a much more light floury consistency
and then slowly sift it into water.
You always add your powder into the water, always.
You don't do the reverse.
And this is very very different than algenate.
Even though it looks the same, completely different
material, you never want to confuse the two.
You never want to mix up hydrocal thinking you're mixing
up algenate.
So be very organized, be very careful about how you
separate the two materials.
Again, I will use the term plaster when I mean hydrocal,
I'm using white hydrocal.
Plaster, it's a generic terms for all different types
of gypsums.
And what Cleave's doing right now is he's just slowly
sifting the powder into the water.
You can weigh out your ingredients, typically we do it
by eye.
There's an old trick that I'll explain how you can tell
when you have enough plaster in the water.
And the same thing goes for the hydrocal that I did
with the algenate.
The temperature of the water will effect the set time
of the plaster.
This material is also referred to as stone,
that's another generic term.
Plaster, stone, these are all just generic terms,
and under that you have your subdivisions of hydrocal,
hydrocal B11, pottery plaster, which is white but it's
very porous, ultracal 30 which we use to make molds
'cause there's low expansion, it's gray.
There's peach stones and dental stones,
each of them have their own unique properties.
For this purpose, again for the casts, usually we'll make
it out of white hydrocal.
Sometimes if there's a need or if we're in a bit of
a rush we'll go right to the ultracal,
that can get a little tricky, but the proper way is to
do it on the white hydrocal and then do the sculpture
on top of that.
And then create your ultracal molds.
So right now you can see that the plaster's not really
soaking in that much anymore, it's kind of settling
on the top.
What you want to have it look like is a term that's
referred to as like a dry river bed where the water
gets totally soaked in and it looks like there's
cracks on the surface, that's how you know when your
plaster is ready to mix.
You don't want to mix it too quick 'cause it'll
effect the strength of the gypsum,
but you want to have it, as you can see,
it looks like a mud cracked dry lake bed.
That's the look you want, you want all these white
powders to be completely absorbed by the moisture.
Then we're gonna mix the gypsum by hand.
Some people use a drill with a little tool on it
that's a circular paddle bit.
That goes a lot quicker.
Again, we'll just do it by hand today since most
people don't have those tools.
So by hand is totally fine, just mix it for a few minutes.
Mix it real thorough so it's a nice smooth creamy
consistency and we'll pour it in the mold and generate
our positive.
This whole process also, by the way, will be duplicated
for the other hand, for the right hand.
We're gonna do the exact same thing when we do
the other hand, we're just gonna do it again.
One of the things you want to be careful of is
trapping air.
A lot of times because of the orientation of the mold,
when you pour the plaster in, because it's a little
thicker, it'll want to create air bubbles.
Sometimes a tip of the finger won't fill or there'll
be little surface bubbles on the positive.
There's several things you can do to reduce that,
one of them is putting this on a vibrating table
and it vibrates all the bubbles up.
What we're gonna do today is pour the plaster in,
kind of rock it around, pour it out and then pour
it back in.
So that'll help reduce the chances of getting any
air bubbles.
And the important thing when mixing your plaster is
you don't want any lumps.
You want to get this, you really want to get this nice
and smooth and creamy and no lumps.
So we're gonna mix it for a few minutes.
When mixing the plaster, the more you mix,
the longer you mix, the quicker it's gonna set up.
So that's another thing to keep in mind.
And plaster goes through several stages as it sets up.
So you'll know when you're--
like right now that's a pretty good consistency right now
for getting all the detail.
You don't want it too thick, you don't want it too thin,
that's just about perfect.
Pour it out.
This is her left hand, right?
So left hand, the thumb would be here.
I'm banging it, there's still plaster in there and
the reason I'm banging it is the plaster is working
it's way down into the fingers and hopefully we're not
gonna trap any air.
You always run that risk.
Make sure you get the thumb.
Hold it there for a sec, I'm gonna pour a little bit out.
Just want to make sure that thumb fills.
I'm tilting it on it's side right now 'cause the thumb is
here, I want to make sure if there's any air it's gonna
want to be popped out the top, if there is any air
in there, there's a little air in this.
The value of doing a life cast on custom hand
as opposed to doing it on a generic is you're guaranteed,
no pun intended, of it fitting like a glove.
Everyone's hand anatomy is slightly different.
Like knuckles bend different, their proportion from
here to here, the distance of the fingers is different.
This ensures that it's gonna be the best fit possible.
Now, sometimes you'll get lucky and a generic,
you can sculpt a generic piece and it might fit on
someone's hand, but this one is a guarantee that it will.
Again, banging it helps work out all the bubbles.
Alright.
Now at this point the best thing to do is just let it set.
Pat some, maybe see a bubble.
There we go.
See how the bubbles come to the surface when you tap
the mold, that's what you want.
You don't want any bubbles in your plaster.
Once you've tapped all the bubbles out and the mold
is filled I'm gonna let the plaster set and while
that's setting we're gonna start on our other hand.