Art Clay & Glass

[Metalman]

elvis8et writes:
Hi, very new to forums and dichroic glass, but need help. Just about all of the glass I had in my kiln shatterrrred when i took it out of the kiln.  If anyone can give me a few pointers it would be greatly appreciated. Thanks.

Metalman:
There are a number of factors related to glass, glass fusing and combining glass with Art Clay Silver.  Those would be the materials [glass, metals]; the equipment [kiln]; and the methods.  There is a fair amount of tech in this.  Its not overly intense but moderately critical.
Glass:There are 3 critical factors with glass.
1] Annealing: This is necessary because as the glass cools, stress builds up – this could be the source of the ‘shattering’ you mentioned.  Glass must cool through the range from about 1050 F down to 900/850 F slowly to allow the stress lines to relax. The thickness of the piece of glass affects this temperature ‘ramp’ as it is called. Small pieces under ¼” shouldn’t be a problem.
2] Compatibility:  All glass is not made the same.  As the chemistry changes, the COE changes. The COE is the Coefficient of Expansion, this has to do with how much or how little the glass expands or contracts when heated or cooled. If you fuse glass together, the glass needs top be ‘compatible’, meaning that the COE for each piece of glass matches.  A number of glass companies have been doing a lot of testing and balancing to make their glass compatible across their line of colors.  There are currently listings for COE 90 and COE 96.  You can only fuse glass that has the same COE.  You can fuse any glass to pieces of itself, but they should come tfrom the same sheet of glass, as the chemistry changes from sheet to sheet of glass.  This is why some manufacturers are making an effort to make their glass to a controlled range.
3] Shock:  Glass, as well as many natural stones are sensitive to heat shock. You must leave the kiln closed until it comes down in temperature to room temperature, that is, to a temperature you can touch without pain.
Kiln:For glass work, you need to run the temperature up in a controlled way [‘ramping up’] do your fusing, you can cool quickly down to 1050/1100 F then you need to ramp down slowly through the annealing range, then cool slowly. There are books and charts and more information for all of this.  You kiln needs to have the controls to do these operations as well as enough insulation to allow for slow cooling.  Glass does not take kindly to sudden temperature changes.  I find it easiest to use a computer driven time-temperature controlled kiln.
Methods:Reading through the above notes will give you an idea of what is necessary.  There is information available out there.  If you are going to do a lot of fusing, getting some additioanl information will be a benefit.  There are kiln wash/kiln paper/ shelf texture issues, the glass compatibility already mentioned, cleanliness concerns with ssome of the dichro work [some materials, oils, etc. can mark the dichro when you fire.

Final Note:  There is a lot to experiement with glass and the metal clays so some of what you may be trying is an experiment that no one has done  as of yet.  On the other hand, you may not want to be ‘reinventing the wheel’ when it comes to the basic tech.

[Metalman]

Cheryl Wade writes:
I've never used ACS, in fact haven't been able to contact the only UK supplier I know of yet, but am keen to try. I don't even have my own kiln but have access to two kilns at the college where I do a part time course in stained glass, including glass fusing and slumping. Having recently experimented with dichroic glass (beautiful stuff!'> and heard about ACS I want to try combining glass and ACS. Q&As I've seen about the clay all recommend small size kilns but the kilns to which I have access are both large, one 3' x 2' and the other about 2' x 1', both have electronic controllers and programmers so controlling the temperatures is no problem. My questions are, can I use these kilns for ACS? Can I use ACS when other work (tack fusing, painting) is also in the kiln or will any residues from the clay affect the other glass? Sorry to be so long winded. I think this is the best site I have so far come across. Thank you.
Cheryl  
Metalman:  
Cheryl,
Great to hear from you.  Do let me know if you continue to have supplier problems in the UK - I may be able to help.
I can't think of any reason that the larger kilns would be a problem as long as the temperature control is solid.  What you describe sounds like glass fusing, slumping and painting activities.  I wouldn't fire silver clay with the other materials until you do some experiments.  I have done a fair amount of firing of Art Clay and glass.  There are silver stain concerns. I was also doing an experiment and reused some kiln fiber to support glass that I had fired Art Clay beads on.  This silver stained the glass, SO !?!.......
Experiments are in order.  I would be mildly concerned about hot spots in the kilns, but a good glass kiln should be pretty even.

[Metalman]

Cat writes:
I rubber stamped an image onto ACS and fired it.  Now I would like to cover the embossed image with dichroic glass.  I would like to use clear thin 90 COE sheet glass.  Will this work?  Am I likely to trap bubbles in the low areas of the embossed image?  Should  the dichroic coated side go on top or next to the silver?  Will the silver stain the glass?  Thanks for your help.  
CAT  
Metalman:  
Great question, and you have most of the concerns that are relevant. You can do a lot with glass and  Art Clay.  If you fire to 1472 for 30 min. the glass will melt and move quite a bit.  Because of the porosity of the Art Clay, the air which might cause bubbles doesn't have to be trapped.  This would be a method when you are firng the Art Clay and including the glass at the same time.
You can also 'tack' the glass by fitting it into already fired Art Clay and running it up to 1470 for a minute or two and then cooling.  Most of the time when I am firing with glass, I get it to temp. and then crash cool it to about 1100F and then do a short soak and let it cool slowly to anneal the glass.
I think our best results are with the dichroic side up or inside if there is more then one layer.  
The silver can and/or will stain the glass.  There are 3 things to do here:  
1st - fire the Art Clay first, then add the glass in a second firing, this will minimize the staining.
2nd- make sure, if you are building the glass into the clay that the glass is really clean before you fire, I had one piece where there was small residues of Silver Clay in the ripples of a piece of dichro and the silver interacted with the metals  of the surface of the dichroic and what a mess.
3rd - This is a strange one but it works - if you use a "sharpie' pen made by the Sanford company and coat your glass with it before you fire it, it will keep the silver stain off - Don't ask me why but this  works.
We have been experimenting for about 3 years with this with generally excellant results.  Some of the time when the silver part of the piece surrounds the glass too closely, we get incompatability cracking - I haven't quite figured out what the problem is when this happens yet.  I feel like sometimes it cracks and sometimes it doesn't but I know there is a detail I haven't observed yet.
Suffice it to say that this is one of the experiment zones and off you go. All in all, we have not had many failures so go for it.

Thanks!  I am off to a family reunion for a few days, but I think I might have to order some supplies for when I get home....
-Laura

[Metalman]

The use of paper type is an experiment you should try.  I think it may work out well. You may get some silver staining around the piece of silver but not so badly as to be objectionable.  I am inclined to think that the syringe work on top of the glass will not stay but you should test it.  We [Margot and I] have done a number of piece with small scale inclusions as you are describing.  Most of them have worked fine - then there has been the occasional one that cracks up and/or off.  I have not quite sorted out why but I think it has to do with thin smallish scale ACS additions working better then larger or thick pieces.
3 notes:  1] Art Clay 650 fires at 1200°F for 1/2 hour - more compatible with some glass work 2] You can tack ACS and glass together firing at 1550°F for 3 to 10 mins.  3] ACS 650 Overlay Paste works great with a variety of glass applications
 The book Art Clay Silver & Gold [R&T cat #: 62-399] has a good section on glass and ACS together, and 2 projects with glass
All of this means that there are Art Clay and glass experiments in your future.  If you have results you don't like - ask me more about the tech or what you think happened and we cah try to figure it out.

I have an idea for a project that would require me to sort of inlay ACS into fused glass.  It wouldn't have to be in the glass, just sort of laid on top.  
I fuse with COE 90 glass and what I was thinking I might be able to do is to fuse the piece fully, then cut an image out of the 650 ACS paper type, dry it, lay it on top of the fused piece, and fire.  The other thought I had would be to "draw" the image on top of the fused glass with syringe-type ACS 650, but then I thought that the shrinkage might cause problems.
Do either of these sound like they might work?
Thanks for any help you can offer!
Laura

[Metalman]

The ACS works great with glass as long as you leave a certain amount of open area for the glass to move.  A lot of folks are working with the glass cabochon/ Art Clay setting.  There are two projects fusing glass on to ACS in the 'Art Clay Silver & Gold book [ R&T cat #:62-399].  Some of this is just a question of experiments finding what really sings for your design sense.  As to frits, are they high or low fire? How thick are you thinking?  I have not had warping problems with COE90 or with borosilicates.  I have had perhaps 10% of my pieces with glass crack for unexplained reasons but I am suspecting some subtle expansion/contraction consideration.
Keep us posted

[blazinghussy]

Hi folks '>  I just recently got into lampworking, which led to the purchase of a kiln, which led to the purchase of some ACS among other things (yeah, I need more expensive mediums to work in like I need an enema).
Anyway, I'm having a bit of confusion.  I'm wondering if I can fire a 'setting' of ACS in the kiln, let it cool a bit, fill it with frit, and pop it back in the kiln to fuse.  It seems to me this would work quite well, but I've heard of a potential warping problem with the ACS.  Can someone clarify for me?
I also thought of making fused cabochons first, then building an ACS setting around them and firing it, but I think this would crack like mad.
I'm going nuts here, just got my R&T order yesterday and I want to play!!  But I'm not sure which method would work best.
Help!
BlazingHussy

[Metalman]

The concern here is that you can/could get silverstaining on your glass.  This is a yellowish coloration on your glass from silver particles or fumes.  I have not had a problem with this and I mix my firings with regularity.  I am careful not to mix my kiln blanket or fiber materials as I have noticed some residue effects if I support and fire Art Clay and then support and fire glass.
Hope this helps

[Metalfairy]

I've heard that you can't (or shouldn't) fire glass beads in your kiln after firing the metal clays in it. Is there any truth in this or is did someone just have a bad experience and now its law?  I guess the fear is the silver leaves pieces of silver that gets on the glass in the next firing.

[Metalman]

Merged Question from SB :
I would like to get a regular old glass bowl [ you know like from the thrift store or Walmart] and over lay the Art Clay syringe form on it.  Do I kiln fire that? Torch Fire?
I also have had problems with the ACS 'coppering" [turning orange?]
It is also breaking apart alot
and I feel like it takes way too much clay to make anything.

Metalman Answers:
1] Regarding the bowl: This can be done, but you will need to figure out some complexities.
A} Because of the heating/cooling considerations, you will have to fire any glass like this in a kiln
B} Glass begins to move [or melt] at about 1150°F on up, it depends on the chemistry of the glass.
So you will need to use ACS 650 line so that you can fire at 1200°F for 30 mins, the higher temp. you use, the more the glass may ‘slump’ [the beginning stages of melting]
C} Since the glass will move you will need to support it. Using the fiber blankets [R&T # 69-181] to build a support can keep the distortion to a minimum.  The shape will change at 1200°F, the better your support, the less the distortion
D} You will probably find that the bonding between the Syringe form and the glass will go better if you paint in the lines first with a line of 650 Overlay Paste.  The consistency is finer and bonds to glass and ceramic surfaces better than the clay.  I usually do a thin paste coating as a footing to where I want to work. Then I fire it.  I don’t do any brushing or polishing when it comes out of the kiln, I take it right back to the bench and put my next layer on, in your case that would be the syringe work. When dry and the way I want it – another ½ hour firing at 1200°F.  At this point, especially on the scale of a bowl, you will probably have some shrinkage cracks – so again, no brushing or burnishing – go right back to the work bench and do your repairs – then fire again.  With luck and some experimental practice you can do this in 3 or 4 firings. IT IS WORTH IT, this kind of stuff looks great as far as I am concerned
E} When you are firing you will need to let the kiln cool down slow.  I think, depending on the thickness of parts of the bowl, you may need to heat up slow and come back down slow.
F} If you find a ‘Pyrex’ bowl, you will have less shape distortion [this could be any sort of borosilicate glass] because its melting point is higher
G} I highly recommend finding further information about slumping and fusing glass – this will give you details about kilnwork with glass

2] “Coppering” – My first guess is that this is the first stage of the silver tarnishing.  This is the same process that we accelerate by using Liver of Sulfur for a patina or Silver Black.  I have heard of some folks using bleach to blacken their pieces.  It would be unusual for this to happen in your studio on a regular basis.  I have had ACS pieces on my bench for 6 to 8 months with no tarnishing.  After that, around a year out, I get some of that effect which you have called ‘coppering’.  IF there is some source of sulfur in your studio[rubber bands will cause it], or your environment – that is probably the culprit.  This tarnish does not damage your piece – it will brush or polish right off – IF it is happening a lot and quickly keep your pieces in a box with some of the silver protection strips [R&T# 63-538, pg 275]

3] “Breaking of pieces”Hmmmmm…..!!  I suspect underfiring first – Are you mostly torch firing?  It needs to be up to a decent middle red glow. Remember that the timing starts once you reach the full heat of your firing, not before.  
4] “it takes way too much clay to make anything” Well, this depends on what you are making.  If you are doing a lot of syringe work – you may find this seemingly true.  I do a combination of fine silver wire and syringe so that the structural component comes from the wire and the ornamental component comes from the Art Clay.  You may want to strategize regarding this and you design development. Give me a call if you need help with this.
--------------
Metalman
Art Clay Silver Master Instructor

[Metalman]

From Beth at:
www.silverwearable.com

Hi Kurt,
 
There is a way to form silver around borosilicate glass without having to endlessly repair and refire, and it can be fired with a torch! How, you ask? It's the magical substance we all have in our homes and offices. Toilet paper! Preferably the unscented, 2-ply kind.
 
I use a water mister, one sheet of TP torn into 1/4" to 1/2" wide strips, and a bit of patience. Since I work with borosilicate bottles of very small size (1 to 1 1/4" diameter) I stick a chop stick in the neck opening to hold it, then I mist the bottle lightly. Remember, the more water you use, the longer it takes to dry. Then I start winding the strips over, across and around, overlapping seams as I go.
 
When my bottle is about 10% larger wrapped than it was unwrapped, I give it all one final mist and push down any sticky out parts that shouldn't be there. I stick the chop stick into a spool of thread or narrow necked bottle to hold it upright and let it dry, thoroughly. This usually takes about a day.
 
If I choose to alter the shape of the bottle, I build up places with little wads of TP before I start wrapping. When it's the shape I want and dry, I use the syringe to draw what ever design I choose over the entire bottle, then let that dry for a day or so, then sand and file and get it all cleaned up and ready to fire.
 
I fire it with a butane torch, usually for about 90 seconds (longer for bigger pieces) at the medium red stage. I find that laying the bottle on the fire brick (without the chop stick, of course) works perfectly well and both sides get done at the same time after the brick is heated up all around it. The TP turns to ash, the silver shrinks, the bond or capture is complete and tada! It's a done deal. You do have to have a fairly light hand with a wire brush, especially if you're using a dremel, but with a bit of care, it looks great!
 
I really hope you try this and see what you can design. It's been a riot for me!
 
Hey - Thanks Beth - Way cool!!