Hydoperm details?

I'm getting trapped air bubbles using hydroperm. I'm thinking that there
might be 2 causes.

#1. I am ramping up extremely fast to 1400 after the initial slow heat up
to 1000. This is to try and avoid devit. My denver can do it in about 10
minutes which I'm thinking is maybe to fast and is not long enough for the
air to escape through the plaster.

#2, I mixed a batch 1.5 part plaster to 1 part water, whipped it up and
got a pretty frothy and what I thought was thin mix. So I added more
plaster next time, 2 part plaster to 1 part water. got something more like
a batter but not frothy and no visible bubbles after the whipping. So maybe
if its to thick it wont have the bubbles necessary to make air escape holes?

What do y'all think
Liam

"Liam Striker" wrote in message
. ..
I'm getting trapped air bubbles using hydroperm. I'm thinking that there
might be 2 causes.

#1. I am ramping up extremely fast to 1400 after the initial slow heat up
to 1000. This is to try and avoid devit. My denver can do it in about 10
minutes which I'm thinking is maybe to fast and is not long enough for the
air to escape through the plaster.

#2, I mixed a batch 1.5 part plaster to 1 part water, whipped it up and
got a pretty frothy and what I thought was thin mix. So I added more
plaster next time, 2 part plaster to 1 part water. got something more
like
a batter but not frothy and no visible bubbles after the whipping. So
maybe
if its to thick it wont have the bubbles necessary to make air escape
holes?

What do y'all think
Liam



Apology for length at the end!

OK, more description needed here. "getting trapped air bubbles using
hydroperm"

what is your mold shaped like? Is this a mold for a bent panel lamp? What
is your bending history, yup, I want to know how much bending you have done.

"I am ramping up extremely fast to 1400 after the initial slow heat up to
1000"

This does not matter one bit, bending is a time/temperature realationship,
by going too fast,which you are not, you just won't bend the glass as much
as if you went slower to the same temp. But that temp is really hot for
bending, what glass are you using? and how much detail are you trying to
get?


"batch 1.5 part plaster to 1 part water, whipped it up and
got a pretty frothy and what I thought was thin mix. "

this is the mix ratio that US Gypsum recommends, actually it is by weight,
did you get a folder of info from them when you bought the plaster? gives
mixing ratios, but you don't need it, it is a weak mold for metal casting
"one offs" , does you no good for what you are doing.

Give me an idea of the project, but in general, I start with a small -
medium mixing bowl, 1/2 full of water,( I don't measure or weigh anything,
you don't need to for use with glass for bending, its by eye), then get a
scoop of plaster and sort of sift/shake/float the plaster into the water,
when it absorbs the water it sinks, just keepshaking the plaster into the
water, don't wait for it to sink, it will happen. Try to do it evenly so
you get an even layer in the water until there is as much palaster as water,
or so it appears, then keep going fo another 1/2 in , about(with practice
you get better, the stuff is not expensive, if you miss one while learning,
it happens), let it "slake" for a few minutes, not long, less than 5 min.
Use a "mixing whisk" from the dollar store to whisk it up and get a good
mix, about the thickness of pancake batter, or cake batter, (You do cook
don't you?), then apply it to your mold. The first coat on will be really
thin, by comparison, to the thickness it will be in a few minutes. At the
mixture I gave you , you have about 5 min. working time before it starts to
"go off" after which time, you can't mess with it much. You will find out
all the tricks the more molds you make.

Those bubbles you were refering to, if they were actually bubbles casused by
the glass not dropping far enough into the mold, drill a small hole in the
mold at the deepest spot., that will let the air out the bottom, just like
the commercial molds., and put the mold up off the floor of the kiln on
posts so the air gets out and so tmeperature is even all around the mold.

Sorry for being so long winded.

what is your mold shaped like? Is this a mold for a bent panel lamp?
What
is your bending history, yup, I want to know how much bending you have
done.

3 projects.
#1 bent panel lamp, typical K11 inserts 11"x6". I have no problem with
this.

#2 bent panel lamp, each panel is about 4" by 2", and bent about 1 inch into
a bowl shape. they have quit a few dimples slumped into the originals. I
am slumping into the mold because the dimple/detail is on the convex side of
the glass. but I am getting trapped air and the glass is not fully comming
into contact with the mold at the bottom, and I'm not getting the detail on
the bottom of the mold. I've fired to several top temps up to 1400 which did
not sink to the bottom of the mold. 1450 got close but the glass started to
contract. Maybe I should just hold at 1400 for a while. It doesn't seem
that the glass isn't hot enough, it seems that there is a trapped bubble at
the bottom. I'm about ready to drill a hole, but was hoping that by using
hydroperm I could avoid this.

#3 duplicating a textrue of another glass for replacement in a stained
glass panel. The glass isn't dropping all the way into the crevices. This
is making for a smoother texture.

But that temp is really hot for bending, what glass are you using? and how
much detail are you trying to get?

exact detail
using several different glasses. Armstrong, Kokomo mostly

Your mixing instructions are just about what I am doing. Maybee I'm going a
little to thick with to much plaster. Do you see visible bubbles in the
plaster when you are done?

Those bubbles you were refering to, if they were actually bubbles casused
by
the glass not dropping far enough into the mold, drill a small hole in the
mold at the deepest spot.,

Ya I'm going to try that, but that doesn't help with the glass sheet texture
in project #3.

Liam

#2 bent panel lamp, each panel is about 4" by 2", and bent about 1 inch
into
a bowl shape.

This isn't all that radical? hmm

they have quit a few dimples slumped into the originals. I
am slumping into the mold because the dimple/detail is on the convex side
of
the glass. but I am getting trapped air and the glass is not fully
comming
into contact with the mold at the bottom,

OK, drill a tiny hole, or 2, to let the air out, don't know why air WOULD
go thru the plaster? I alwayd drill holes in the deepest spot on a slumping
mold, whatever the mold is made of. Blanket is ok, but all plasters get a
hole, and then you will find you don't need to go as high in temp either,
that was hot air holding the glass up, not a bubble formed by anything
foreign. 1285 should be high enough to get that to drop into a mold of that
size and shape, and pick up the dimples too. If there are several deep
spots around the dimples, drill several holes, by only going to 1285 you are
not going to have any problem with a hole.


and I'm not getting the detail on
the bottom of the mold. I've fired to several top temps up to 1400 which
did
not sink to the bottom of the mold. 1450 got close but the glass started
to
contract. Maybe I should just hold at 1400 for a while. It doesn't seem
that the glass isn't hot enough, it seems that there is a trapped bubble
at
the bottom. I'm about ready to drill a hole, but was hoping that by using
hydroperm I could avoid this.

Why avoid it? You don't see any sign of it on the glass as long as you
don't go to those extreme high heats for bending?











#3 duplicating a textrue of another glass for replacement in a stained
glass panel. The glass isn't dropping all the way into the crevices.
This
is making for a smoother texture.

But that temp is really hot for bending, what glass are you using? and
how
much detail are you trying to get?

exact detail
using several different glasses. Armstrong, Kokomo mostly

Your mixing instructions are just about what I am doing. Maybee I'm going
a
little to thick with to much plaster. Do you see visible bubbles in the
plaster when you are done?

Those bubbles you were refering to, if they were actually bubbles
casused
by
the glass not dropping far enough into the mold, drill a small hole in
the
mold at the deepest spot.,

Ya I'm going to try that, but that doesn't help with the glass sheet
texture
in project #3.

Liam

drill holes worked great. But I was under the impression that using
hydroperm I wouldn't need to do this, no that it's a bid deal.
Anyways, worked great and lamp looks great. by the by, it was a Handel
Similar to
http://www.mamajeans.com/handel.htm
3rd pic down but with 4 shades.

Thanks again

Liam

"Liam Striker" wrote in message
. ..
drill holes worked great. But I was under the impression that using
hydroperm I wouldn't need to do this, no that it's a bid deal.
Anyways, worked great and lamp looks great. by the by, it was a Handel
Similar to
http://www.mamajeans.com/handel.htm
3rd pic down but with 4 shades.

Thanks again

Liam

I don't know where the idea that you wouldn't have to drill holes with
Hydroperm came from? Deep depressions always need it, but in bending that
particular shade, I usually fire twice. One slumped in to get it started,
and then draped over to show the "ridge". and let it form , If you look at
the original, usually there are mold marks on the inside, there are other
ways too.