first sand cast project

[John]

Bert, did you find that in some parts where the alumina hydrate was that it was a little fumy/hazy? I myself use benntonite which gives a super clear finish.
The more you put on the clearer the pattern becomes.

John

[Bert Weiss]

Bert, did you find that in some parts where the alumina hydrate was that it was a little fumy/hazy? I myself use benntonite which gives a super clear finish.
The more you put on the clearer the pattern becomes.

John

I Don't get fumy hazy with my alumina mix. If I did, I would be trying to find other materials. Kaolin gets you the hazy thing after the first firing so I don't use it. I was leary of bentonite because I thought is was similar to kaolin. I can get some so I'll have to give it a try on the sand mix. It sounds like a good material to do the top dusting with. Thanks for the tip.

The best trick I have found is to fire to 1365ºF or so with a 1 hour soak. The back stays shinier than if I fire hotter with a short soak.

[John]

The best trick I have found is to fire to 1365ºF or so with a 1 hour soak. The back stays shinier than if I fire hotter with a short soak.

Looks to be a similar fire to mine. I have used Bentonite in the sand mix as well as the top coat. As I said before I use more for a clearer finish in parts and less in others to diffuse.

John

[Kathie Karancz]

Hey Bert: Absolutely loved the table!!! Love the little specks in the texture. Question: I get tons of float given to me by a picture framer, so it's that really thin (don't know thickness) glass. If I want to fuse it together to make something thick (I know compatibility would still be an issue), but what would you suggest for a full fuse schedule, etc.?? And then a slump if I want to make a bowl for example.... Hope that makes sense...
Thanks for any help
Kathie

[Bert Weiss]

Hey Bert: Absolutely loved the table!!! Love the little specks in the texture. Question: I get tons of float given to me by a picture framer, so it's that really thin (don't know thickness) glass. If I want to fuse it together to make something thick (I know compatibility would still be an issue), but what would you suggest for a full fuse schedule, etc.?? And then a slump if I want to make a bowl for example.... Hope that makes sense...
Thanks for any help
Kathie

Kathie

I would stack it up and fire to 1220 and soak for an hour then up to 1420 and soak for maybe another hour and then anneal. Ramp up speeds are dependent on your kiln. Annealing is dependent on the thickness and bubbleivity of the finished piece. You will probably have to borax the top piece. How thick do you want to go? Slump temp will depend on the size and shape of the slump. I do it anywhere between 1240 and 1350.

[charlie]

won't it have to be dammed in some fashion to prevent spreading?

[Kathie Karancz]

I was also just thinking about having to dam it.... What I think I will do is try a little square piece (maybe 4"x4"), dam it and then fill it up with strips of the float. I was also concerned about the devit - so if I just wash the glass and then spray it with something and then try Bert's schedule. Hopefully that way I can get it up to around 3/4". Thanks guys

[Bert Weiss]

won't it have to be dammed in some fashion to prevent spreading?

I had big trouble the one time I tried to dam stacked float.

[charlie]

then how do you prevent it from trying to get to 1/4"? does it move, albeit slowly, because you fire cooler and not as long?

[Bert Weiss]

then how do you prevent it from trying to get to 1/4"? does it move, albeit slowly, because you fire cooler and not as long?

Most of the thick glass projects I do are table tops that do not have to fit an exact size so I don't worry about a little spread. It takes a lot of heat and time before the glass actually reaches 1/4" LOL. Mine only spreads a half of an inch or so.

The time I had to do an exact size, I set up a dam. I made the glass a bit smaller than the dam. It spread in to the dam and curled up, then it shrunk back leaving me with a smaller dimension than I wanted and I had to cut off the curled up end. Essentially it was disastrous. I had to include a stainless steel channel to resolve the edge issue.

[Kathie Karancz]

Thanks Bert for letting me know about your disaster with daming. I will try just making a box of float glass and then filling it up with strips of float (no daming) and see what happens. I'm really curious now. Maybe even throw a little coloured frit into it.......... hmmmmmm?????
I'll let you know what happened
Kathie
P.S.: It's freezing up here!!!! Minus 17 degrees Celcius this morning - I gotta get out of here...

[Cheryl]

now I've gotta find a foundry. Bert, you're such a bad influence!

[Dean Hubbard]

Yaa, I gotta get my hands on some geen sand too! I will have to drive six hours one way or have it shipped.
Bert, what impressed me most about the table, is how shiny it came out. That's the control I want to achieve with float glass, without all the cold work. Charlie informed me that this thread was the first public showing of sand casting glass this way in a kiln. He said that people from Australia have been doing for some time, but have kept their techniques proprietary.
I have looked in the archives and saw the thing about http://www.ozoneglass.com and I am impressed with the control you can achieve as far as having texture and clear areas using float glass. I see also from posts in the archive that early on you were oppossed to sand casting and preferred fiber paper to get what you wanted. I gotta ask you, are you as excited about this technique now as I am?
Does heating all that sand up slow things down quite a bit?
Thanks for sharing Bert, you are an inspiration to me!
Let's keep this thread going!

[Bert Weiss]

Yaa, I gotta get my hands on some geen sand too! I will have to drive six hours one way or have it shipped.
Bert, what impressed me most about the table, is how shiny it came out. That's the control I want to achieve with float glass, without all the cold work. Charlie informed me that this thread was the first public showing of sand casting glass this way in a kiln. He said that people from Australia have been doing for some time, but have kept their techniques proprietary.
I have looked in the archives and saw the thing about http://www.ozoneglass.com and I am impressed with the control you can achieve as far as having texture and clear areas using float glass. I see also from posts in the archive that early on you were oppossed to sand casting and preferred fiber paper to get what you wanted. I gotta ask you, are you as excited about this technique now as I am?
Does heating all that sand up slow things down quite a bit?
Thanks for sharing Bert, you are an inspiration to me!
Let's keep this thread going!

I am totally excited about it. Shiny is good. It does slow things down quite a bit. No more 12 hour firings. Good though.

The other thing is that many types of sand are possible to use. From cheap play sand from Home Depot to sandblasting grit. I do like the olivine sand though. It is used by the foundry industry for making castings and takes a good impression.

I made a large barrel of sand that I can put in and take out as I need it. Once too much plaster is in it I think that more sand can be mixed in or you can start over.

I first learned to sand cast with molten glass at Pilchuck around 1990. Kiln casting is not significantly different except that the sand is dry and I am using plaster for a seperator instead of carbon. We can thank Pilchuck for spreading this technique across the pond. The technique is a small thing. The application of it is the big deal. Make some great art.

When I posted my picture, I didn't think of it as being a groundbreaking event, just a picture of my new experiment. The recipes I used were actually posted on WGBB a while back as well as some short conversations with attendees of the Warren Langley class at Pilchuck. I first heard about the Pilchuck class when it was about to begin. I'd have liked to have been there, for sure.

[Brian and Jenny Blanthorn]

Yaa, I gotta get my hands on some geen sand too! I will have to drive six hours one way or have it shipped.
Bert, what impressed me most about the table, is how shiny it came out. That's the control I want to achieve with float glass, without all the cold work. Charlie informed me that this thread was the first public showing of sand casting glass this way in a kiln. He said that people from Australia have been doing for some time, but have kept their techniques proprietary.
I have looked in the archives and saw the thing about http://www.ozoneglass.com and I am impressed with the control you can achieve as far as having texture and clear areas using float glass. I see also from posts in the archive that early on you were oppossed to sand casting and preferred fiber paper to get what you wanted. I gotta ask you, are you as excited about this technique now as I am?
Does heating all that sand up slow things down quite a bit?
Thanks for sharing Bert, you are an inspiration to me!
Let's keep this thread going!

I am totally excited about it. Shiny is good. It does slow things down quite a bit. No more 12 hour firings. Good though.

The other thing is that many types of sand are possible to use. From cheap play sand from Home Depot to sandblasting grit. I do like the olivine sand though. It is used by the foundry industry for making castings and takes a good impression.

I made a large barrel of sand that I can put in and take out as I need it. Once too much plaster is in it I think that more sand can be mixed in or you can start over.

I first learned to sand cast with molten glass at Pilchuck around 1990. Kiln casting is not significantly different except that the sand is dry and I am using plaster for a seperator instead of carbon. We can thank Pilchuck for spreading this technique across the pond. The technique is a small thing. The application of it is the big deal. Make some great art.

When I posted my picture, I didn't think of it as being a groundbreaking event, just a picture of my new experiment. The recipes I used were actually posted on WGBB a while back as well as some short conversations with attendees of the Warren Langley class at Pilchuck. I first heard about the Pilchuck class when it was about to begin. I'd have liked to have been there, for sure.

In my own way I 2 am tyring 2 gert the Art without lots of boring work

I have been n always did try 2 concentrate on the results rather than long complecx processes

The technique U R usiong loooks great

As 2 the length of fire what about adding

Perlite / mica 2 the mix

U would need 2 check out the temps

Or crushed low thermal mass kiln bricks

Brian

[Dean Hubbard]

Bert,
I'm a bit confused here. I thought I had a fair understanding of grit/mesh sizes. (Grit and mesh are both the same, grit is the size of the partical that will fit through a mesh sreen, the number specifies how many per inch, right?)
I'll have to drive to S.F. to get the olivine sand but, I want to try a test, so I'm going to use some #220 silica sand that I have on hand. I found some bentonite locally and the bag says it is a #200 Vol-Clay. This stuff is like dust, a pinch of it rubbed between your thumb and fore finger feels like flour, not like fine sand. Is this stuff sized differently than sand, like by microns or something, or is the bag mis-marked? Also a few weeks ago when I bought some #1 pottery plaster and silica to go with it, to make some plater moulds, the lady at the pottery shop told me that both bags were #200, there is no references on each bag to particle size. (They are like powder too)
As far as my test goes, I'm planning to mix some of this powder fine silica in with the #220 silica sand to get a better bed to cast onto. I figure that the powdery silica will help fill in the gaps better between the #220 silica sand grains. As far as dusting the sand bed with bentonite goes, I am planing on filling up a sock or something and basicaly making a pounce bag that I'm going to tap between my hands to sift the bentonite top coat.
Does this sound alright, or would you do different?
Have you tried sand casting on just bentonite?
Please fill me in on the sizng for these powders, because all I am familiar with is mesh or grit sizes for sand.
Thank You

[Brian and Jenny Blanthorn]

I was also just thinking about having to dam it.... What I think I will do is try a little square piece (maybe 4"x4"), dam it and then fill it up with strips of the float. I was also concerned about the devit - so if I just wash the glass and then spray it with something and then try Bert's schedule. Hopefully that way I can get it up to around 3/4". Thanks guys

There realy is a ton on this in the archives

Specifically I am talking abut multi layered fuzing with no bubbles

This realy is a lifes work

But have a dig arround in the archives

Devit

Slow fire slow firing

Look out 4 my name that will also bring in other people in that topic

In brief keep the borax off the bottom + sides use a little put on all interfaces fire real slow

Brian

[Brian and Jenny Blanthorn]

Bert,
I'm a bit confused here. I thought I had a fair understanding of grit/mesh sizes. (Grit and mesh are both the same, grit is the size of the partical that will fit through a mesh sreen, the number specifies how many per inch, right?)
I'll have to drive to S.F. to get the olivine sand but, I want to try a test, so I'm going to use some #220 silica sand that I have on hand. I found some bentonite locally and the bag says it is a #200 Vol-Clay. This stuff is like dust, a pinch of it rubbed between your thumb and fore finger feels like flour, not like fine sand. Is this stuff sized differently than sand, like by microns or something, or is the bag mis-marked? Also a few weeks ago when I bought some #1 pottery plaster and silica to go with it, to make some plater moulds, the lady at the pottery shop told me that both bags were #200, there is no references on each bag to particle size. (They are like powder too)
As far as my test goes, I'm planning to mix some of this powder fine silica in with the #220 silica sand to get a better bed to cast onto. I figure that the powdery silica will help fill in the gaps better between the #220 silica sand grains. As far as dusting the sand bed with bentonite goes, I am planing on filling up a sock or something and basicaly making a pounce bag that I'm going to tap between my hands to sift the bentonite top coat.
Does this sound alright, or would you do different?
Have you tried sand casting on just bentonite?
Please fill me in on the sizng for these powders, because all I am familiar with is mesh or grit sizes for sand.
Thank You

In brief bentonite is a

MONTMORILLONITE clay mineral with an expanding structure that is used as a lubricant in pottery bodies or as a filler or suspending agent.

Al2O3-5SiO2-7H2O

4 those that wanna know sodium is Na

So U probably not gona get a propper grain size as it is a soft material when dry

I cannot find a melt temp 4 it

And I do have a lot of tools at hand 2 do so

I cant spend any more time on this

But here is what I got on the net so far

http://www.ceramicindustry.com/FILES/HT ... 2,,00.html

In the first search box click bentonite

If U do find melt temps let me know

I use it as a suspension agent

XXXXXXXXXXXXX

Did a bit more searching

http://www.canbensan.com/2.htm

Foundery link got sulfur /sulphur in it ?

Did get a melt temp on this site over 1000 c but cant get back in now 2 check

Currently site not working so cant get back in2 it


http://www.afcil.com/otherproducts.htm

AFCIBOND is a range of an ultimate Sodium based Bentonite for foundry that acts as an excellent binding agent for sand in Steel and Cast Iron foundries and also develops high dry compression strength to prevent sand erosion, cuts, washes etc.

Looks like the foundery business uses bentonite

XXXXXXXXXXXXXXXX

Got the site 2 work

http://www.canbensan.com/2.htm

CANDOK is naturally occurring sodium bentonite that exhibits outstanding characteristics for green sand molding. It imparts very high green compression strength and in the typical manner of sodium bentonite has a moderately high dry strength.

CANDOK differs from other clays in the sense that it has an extraordinary ability to retain bonding ability after heat exposure . The foundry is able to maintain active clay levels with reduced additions of bentonite or replacement sand by the help of this superior thermal durability . This feature makes CANDOK ideal for applications that require high heat loads or high melt temperatures , such as iron foundries operating with low sand-to-metal ratios or steel foundries . Besides cost savings from lower bentonite adding one additional benefit is that there will be less waste fines to discard so disposal costs will be reduced.

Packaging; CANDOK is packed as 40 kg kraft and plastic lined bags or 500 kg big bags.

TECHNICAL SPECIFICATIONS :

Color
Brown-Cream

Swelling Index
18-25

Swelling Time
Instantaneous

Moisture
9% max.

Green Compression Strength
1.800-2.300gr/cm2

Dry Compression Strength
2.800-3.500gr/ cm2

Dry Screen (passing 75 µm)
91,5%

Montmorrillonite
75% min.

Sintering Temperature
1.050-1.150 o C

I dont know how true the temp is for normal bentonite

Brian

[Bert Weiss]

Bert,
I'm a bit confused here. I thought I had a fair understanding of grit/mesh sizes. (Grit and mesh are both the same, grit is the size of the partical that will fit through a mesh sreen, the number specifies how many per inch, right?)
I'll have to drive to S.F. to get the olivine sand but, I want to try a test, so I'm going to use some #220 silica sand that I have on hand. I found some bentonite locally and the bag says it is a #200 Vol-Clay. This stuff is like dust, a pinch of it rubbed between your thumb and fore finger feels like flour, not like fine sand. Is this stuff sized differently than sand, like by microns or something, or is the bag mis-marked? Also a few weeks ago when I bought some #1 pottery plaster and silica to go with it, to make some plater moulds, the lady at the pottery shop told me that both bags were #200, there is no references on each bag to particle size. (They are like powder too)
As far as my test goes, I'm planning to mix some of this powder fine silica in with the #220 silica sand to get a better bed to cast onto. I figure that the powdery silica will help fill in the gaps better between the #220 silica sand grains. As far as dusting the sand bed with bentonite goes, I am planing on filling up a sock or something and basicaly making a pounce bag that I'm going to tap between my hands to sift the bentonite top coat.
Does this sound alright, or would you do different?
Have you tried sand casting on just bentonite?
Please fill me in on the sizng for these powders, because all I am familiar with is mesh or grit sizes for sand.
Thank You

Dean

The story about particle size is that in order to develop strength, you need a variety of particle sizes. Otherwise a fine powder would do the job. The next trick is to use particles that are less likely to stick. Most of the larger particles stick so you use fine particles that coat the large particles and don't stick.

Play sand is sifted so there are no fines. Fine silica particles are toxic so it is better to avoid them. Large silica particles are not a problem which is why the sell play sand for kids. The foundry supply guy told me that the beach is a much more toxic environment than a foundry, relative to fine silica.

The hot casting technique is to mix olivine sand and bentonite and water and sift it in a box, then coat with carbon. The bentonite helps develop strength. I have not tried bentonite in my dry mix yet, but I will when I get around to it.

I have an 80 mesh sifter that is sized about the diameter of a 5 gallon bucket that I use to sift on the plaster. It is also good to remove stuff that won't go through it.

[charlie holden]

Dean,

Silica is a carcinogen. I wouldn't use silica flour for any application that leaves it dry and open to the shop atmosphere. I only use it when it is going to be encased in plaster and I'm going to stop using it soon. If possible, it should only be mixed in a room with a strong ventilator, or it should be mixed outside. It will dust up and coat every surface of your shop.

ch