kiln casting with metal... please help! - WarmGlass.com

kiln casting with metal... please help!

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froggee501
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kiln casting with metal... please help!

Postby froggee501 » Thu Feb 26, 2004 6:55 pm

http://www.wetcanvas.com/forums/showthread.php?t=169495

^that^ is a link to my thread at wetcanvas... for a quick rundown, I'll be casting something in silver (Monday?), and then I'll be reinvesting it with wax, burn out the wax, and cast it with glass! I've done a LITTLE bit of fusing (actually even have class tonight!) but haven't done ANY casting in glass before.... and this is for a project for school, so it MUST turn out well! Anyway, if any of you have any advice for me, it would be MUCH appreciated!

Thanks in advance!
Emma Tucker

and to avoid any confusion... The metal is cast in the centrifuge, the glass is cast onto the metal in the kiln.

AVLucky
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Postby AVLucky » Thu Feb 26, 2004 7:48 pm

wow...complicated. I am familiar with centrifugal jewelry casting, so I know about the whole investing and burnout procedure. Are you going to try to do that with the glass too? Is that why you had a glass sprue in the diagram? I looked at your sketches and I'm still a little confused about your plans. Glass is definitely not going to behave like metal, and I would hate to see what might happen to all that casting equipment!

I think an easier way might be to fuse (or cast) the glass separately, and then do a second firing where you lay the glass on top of the metal and let it slump through the hole a little bit. Another thing: test, test, test! Try slumping pieces of glass through a hole in copper or silver to see what happens. You're going to have to be really careful about annealing times and metal vs. glass expansion. In other words, if this is for a quick deadline, don't count on getting perfect results right away. In my college jewelry & metals classes we had to make models of everything before we did a "real" one. I hated it at the time, but it's always useful and has become a very necessary practice to retain, no matter what medium I'm working in.

Good Luck!

AVLucky
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Postby AVLucky » Thu Feb 26, 2004 7:51 pm

oops...should have re-read. I guess you're not putting glass in the centrifuge. But when you re-invest, are you doing it the same way you would for a piece of jewelry?

charlie holden
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Postby charlie holden » Thu Feb 26, 2004 8:27 pm

You are trying something that is going to be very difficult. Few people are successful with their first attempt at glass casting. And even when the glass ends up where you want it and in the right shape it is often rough and/or scummy looking, which means it needs cold working -- which is a whole nother thing.

Anyway, you are likely to have more success with a glass with a high lead content and a low softening point so you don't have to melt your metal again. Notice I didn't write "melting" point because glass softens over a wide temperature range. People will refer to "casting temperature", which is soft enough to flow and fill a mold, but may not be hot enough or soft enough for the glass to move into the narrow spaces you are trying for. It will not get as liquid as you are used to the metal getting until the metal is long gone. This is why we test a lot.

You should also look into "Pate de Verre", in which you fill the mold with glass powder before you fire it. This gets glass all the way into the far corners of the mold but also means that the final piece will have a milky look since it will be full of tiny bubbles. It also usually takes time to develop pate de verre skills and techniques.

The silver will color the glass where they touch. Sometimes it goes yellow. Copper will probably turn the glass blue-green.

ch

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Re: kiln casting with metal... please help!

Postby Bert Weiss » Thu Feb 26, 2004 9:17 pm

froggee501 wrote:http://www.wetcanvas.com/forums/showthread.php?t=169495

^that^ is a link to my thread at wetcanvas... for a quick rundown, I'll be casting something in silver (Monday?), and then I'll be reinvesting it with wax, burn out the wax, and cast it with glass! I've done a LITTLE bit of fusing (actually even have class tonight!) but haven't done ANY casting in glass before.... and this is for a project for school, so it MUST turn out well! Anyway, if any of you have any advice for me, it would be MUCH appreciated!

Thanks in advance!
Emma Tucker

and to avoid any confusion... The metal is cast in the centrifuge, the glass is cast onto the metal in the kiln.


Emma

I don't know the melting point of silver or it's expansion coeffecient, but my uneducated guess is that your plan will not work.

You can make a plaster and various other materials investment from a wax positive and cast glass in to it. You might be able to get that to fit together with a silver casting after both have been cooled. However there are contraction coeffecients that will also come in to play so getting them to fit together is a high design challenge.

Your doing post graduate work for your first project. Simplify and maybe you'll have a better first stab at it.
Bert

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Re: kiln casting with metal... please help!

Postby Brad Walker » Thu Feb 26, 2004 9:39 pm

Bert Weiss wrote:[I don't know the melting point of silver or it's expansion coeffecient, but my uneducated guess is that your plan will not work.


I do. http://www.warmglass.com/COESummary.htm#metal

And I'll be surprised if it works, also, at least the way it's described. Dramatically different expansion coefficients, the only chance is if the silver is very, very thin, and that doesn't sound like the case here.

This is a very tough first casting project, especially if you have to get it done in a few days.

froggee501
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Postby froggee501 » Fri Feb 27, 2004 12:14 am

charlie holden wrote:You are trying something that is going to be very difficult.


I have a bad habit of doing that :D

I'm not afraid though....and before I cast the silver, I plan to make a mold of my silver in case something goes wrong.

Anyway, you are likely to have more success with a glass with a high lead content and a low softening point so you don't have to melt your metal again.


what would you recommend? Do you have any that I could buy from you, or know where I could get a little?

You should also look into "Pate de Verre", in which you fill the mold with glass powder before you fire it. This gets glass all the way into the far corners of the mold but also means that the final piece will have a milky look since it will be full of tiny bubbles. It also usually takes time to develop pate de verre skills and techniques.


that's more where I was looking... get the glass into as fine of a grit as I can and do a Pate de verre technique. And I was expecting a milky look, so that won't be a problem.

The silver will color the glass where they touch. Sometimes it goes yellow. Copper will probably turn the glass blue-green.


If I end up using moretti, then I won't have a problem, because I know what colors have what reactions with silver. If I don't use moretti, then I plan to research whatever it is that I do use.

froggee501
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Postby froggee501 » Fri Feb 27, 2004 12:19 am

AVLucky wrote: You're going to have to be really careful about annealing times and metal vs. glass expansion. In other words, if this is for a quick deadline, don't count on getting perfect results right away. In my college jewelry & metals classes we had to make models of everything before we did a "real" one.


I'll anneal as the glass requires, with a little more caution. This isn't for a quick deadline, I figure I can drag this out for three weeks, and I'm almost ready to cast my metal anyway. and as I told charlie, I plan on making a mold of my silver before I cast the glass, so if all else fails, I can redo the project completely in metals.

I guess you're not putting glass in the centrifuge.


nope. :)

But when you re-invest, are you doing it the same way you would for a piece of jewelry?


unless someone tells me a better way of doing it... that's why I'm posting here. :)

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Postby Geri Comstock » Fri Feb 27, 2004 12:23 am

What you're trying to do is basically a form of enameling. I can just about 99% guarantee you that it isn't going to work based on my limited knowledge of enameling.

If I were trying to do this project, I'd cast the silver first. Then I'd make a mold of the area on the silver where you want the glass to be in the shape that you want the glass to be. Invest and cast that separately in glass and then cold join the two (with metal/glass glue like the one Dymax sells).

froggee501
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Re: kiln casting with metal... please help!

Postby froggee501 » Fri Feb 27, 2004 12:24 am

Bert Weiss wrote:I don't know the melting point of silver or it's expansion coeffecient, but my uneducated guess is that your plan will not work.


not if I have anything to do with it... :twisted:

You can make a plaster and various other materials investment from a wax positive and cast glass in to it. You might be able to get that to fit together with a silver casting after both have been cooled.


However, that won't meet the assignment requirements... You have to either make two parts and solder them together (you can't solder glass!) or cast one onto the other.

Your doing post graduate work for your first project. Simplify and maybe you'll have a better first stab at it.


I tend to do idiotic things at times, and tackling things I'm not ready for is one of them. :D However, I'm not afraid of failure... the worst that will happen is that I have to do this over again.

froggee501
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Re: kiln casting with metal... please help!

Postby froggee501 » Fri Feb 27, 2004 12:29 am

Brad Walker wrote:I do. http://www.warmglass.com/COESummary.htm#metal

And I'll be surprised if it works, also, at least the way it's described. Dramatically different expansion coefficients, the only chance is if the silver is very, very thin, and that doesn't sound like the case here.

This is a very tough first casting project, especially if you have to get it done in a few days.


Thank you for the link! It looks like the only metals better than silver would be copper and gold... I don't want to use copper, and gold's expensive! All the other low coefficient ones have way too high of a melting point, prolly couldn't melt them with the jewelry room torches we have... I'll ask though.

I know that it's risky, but glass and silver work well in small quantities, as I've used them in my lampworking... maybe if I forgo the leaf shape on the back of the pendant in glass? then they'd only have to touch RIGHT at the whole, and will be a little stronger...

froggee501
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Postby froggee501 » Fri Feb 27, 2004 12:34 am

Geri Comstock wrote:What you're trying to do is basically a form of enameling. I can just about 99% guarantee you that it isn't going to work based on my limited knowledge of enameling.


I've done enameling before, a little.... it's not enameling, at least if I take the leaf shape off the back... where I'm leaning now is to have just the barest contact between the metal and glass. The flower is raised off the surface.

If I were trying to do this project, I'd cast the silver first. Then I'd make a mold of the area on the silver where you want the glass to be in the shape that you want the glass to be.


I'm doing that much like that...

Invest and cast that separately in glass and then cold join the two (with metal/glass glue like the one Dymax sells).


...and here's where it's different. I need to cast the glass directly into the metal due to the nature of this project... just explained it to Bert.



Thanks everyone for your help, I'll be back to see what more wisdom you have... tomorrow, when I have had decent sleep I'll research into Pate de Verre a little more, see what info I can glean....

Emma :)

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Re: kiln casting with metal... please help!

Postby Brad Walker » Fri Feb 27, 2004 12:39 am

froggee501 wrote:However, that won't meet the assignment requirements... You have to either make two parts and solder them together (you can't solder glass!) or cast one onto the other.


Ah, but you can solder glass! Information on the technique is widely available and people who know how to do it can be found in virtually any town in the US. Not only that, soldering glass to metal using copper foil techniques is so much easier than trying to cast the two together it's like the difference between walking a mile in half an hour and running one in four minutes.

I couldn't run a four minute mile in a few weeks of training, but I bet I could walk one in half an hour. If soldering's ok, just get a book on the copper foil method and solder your glass piece to the copper. Piece of cake.

froggee501
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Re: kiln casting with metal... please help!

Postby froggee501 » Fri Feb 27, 2004 12:46 am

Brad Walker wrote:
froggee501 wrote:However, that won't meet the assignment requirements... You have to either make two parts and solder them together (you can't solder glass!) or cast one onto the other.


Ah, but you can solder glass! Information on the technique is widely available and people who know how to do it can be found in virtually any town in the US. Not only that, soldering glass to metal using copper foil techniques is so much easier than trying to cast the two together it's like the difference between walking a mile in half an hour and running one in four minutes.

I couldn't run a four minute mile in a few weeks of training, but I bet I could walk one in half an hour. If soldering's ok, just get a book on the copper foil method and solder your glass piece to the copper. Piece of cake.


two ways to tell you've got a newbie on your hands:

1. They say something that isn't true! Thanks, I hadn't even thought about that. I've got a stained glass store in town. However, I don't want to use copper at all, I hate the color of it. Is there a silver solder that will work?

2. The darned newbie puts their thread in the wrong forum! Silly me just looked around and found a kiln-casting sub-forum... *sigh* If anyone is in a tizzy over this and wants to move my thread, feel free. :)

Emma

it's like the difference between walking a mile in half an hour and running one in four minutes.


wait, what's the difference, which one's "better"? I hate both anyway... :D

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Postby Geri Comstock » Fri Feb 27, 2004 12:50 am

Soldering stained glass, which I believe is what Brad was talking about is a completely different process than silver soldering.

It's done with copper foil on the edges of the glass, a low temp solder (flows at about 700F) and a soldering iron. Silver soldering is done with a torch at much higher temperatures and glass cannot be soldered to silver using this technique because it will break.

Geri

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Postby Brad Walker » Fri Feb 27, 2004 12:51 am

Emma,

1. All solder is silver. As Geri said, you tape copper foil to the glass and solder on that. And even if solder wasn't silver, you can patina it to be lots of different colors. Go visit your local stained glass shop -- copper foil stained glass is really easy to do -- especially compared to casting.

2. You didn't really have a kiln casting question. You only thought you did.

froggee501
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Postby froggee501 » Fri Feb 27, 2004 1:16 am

wow... I'm getting really confused... Isn't taking a wax model of something, setting it in investment, burning/steaming it out, then setting it in the kiln and melting glass into it in some way kiln casting? If not, then what is?

And let's see if I've got this right.... I attach copper foil to the glass, and solder it using silver solder onto the silver? and I can do this so that NO copper color is seen? and without shocking my glass? wouldn't the heat used to solder still affect the glass? especially considering copper is a good conducter? I'm getting really confused. :oops: I knew that silver soldering like I use in jewelry wouldn't work...

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Postby Geri Comstock » Fri Feb 27, 2004 1:25 am

froggee501 wrote:wow... I'm getting really confused... Isn't taking a wax model of something, setting it in investment, burning/steaming it out, then setting it in the kiln and melting glass into it in some way kiln casting? If not, then what is?


Yes it is, but it probably won't work if you cast glass onto silver, unless you do it using enameling techniques.

froggee501 wrote:And let's see if I've got this right.... I attach copper foil to the glass, and solder it using silver solder onto the silver? and I can do this so that NO copper color is seen? and without shocking my glass? wouldn't the heat used to solder still affect the glass? especially considering copper is a good conducter? I'm getting really confused. :oops: I knew that silver soldering like I use in jewelry wouldn't work...


The color of stained glass solder is sort of silver/pewter, but it's not made from silver. Typically, it is 50% lead and 50% tin, but there are some other formulations, including a lead free version.

The way you'd attach it to the metal is to cast the glass piece separately, wrap copper foil (tape) around the edges and use a soldering iron to melt the low temp solder and melt it to attach the copper foil to the leaf. The copper foil would show if the glass was at all transparent; however, there are silver-backed copper foils that are designed to be used with mirror.

What kind of soldering is required in this class? Silver soldering or stained glass soldering. As I said before, they're completely different processes and if it's a jewelry/metals class of some kind, I suspect your teacher won't want you to do stained glass soldering, they'll want you do to silver soldering with a torch and solder that's actually made from silver and other things.

Good luck!

Geri

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Postby Brad Walker » Fri Feb 27, 2004 1:25 am

froggee501 wrote:wow... I'm getting really confused... Isn't taking a wax model of something, setting it in investment, burning/steaming it out, then setting it in the kiln and melting glass into it in some way kiln casting? If not, then what is?


Yes, that's kiln casting. My comment was really just tongue in cheek, that casting may not be the best way to do what you want to do.

And let's see if I've got this right.... I attach copper foil to the glass, and solder it using silver solder onto the silver? and I can do this so that NO copper color is seen? and without shocking my glass? wouldn't the heat used to solder still affect the glass? especially considering copper is a good conducter? I'm getting really confused. :oops: I knew that silver soldering like I use in jewelry wouldn't work...


You've got the concept. And no, the glass doesn't crack if you do it right. The copper foil stained glass technique has been around for about 100 years (think Tiffany!). You can learn it in a couple of hours.

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Postby Bert Weiss » Fri Feb 27, 2004 10:05 am

Emma

I have an idea for you. Look in to Thompson Enamels. They make a glass frit that is compatible with silver. If you can do this, a more traditional glass on silver technique with a thin layer of glass over the silver is the way to go. Thompson will have a very good understanding of techniques required. Ask for Bill Helwig when you cal there. Bill is an expert on all kinds of metal enameling. It will truly be glass fused to metal. I'm not sure of the number. They are in Newport Kentucky.
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