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Q & A Monday, 9/9/13

Jodi McRaney RushoHey there!  Here we are back again for another Q & A Monday.  All of these questions were received via e-mail and answered directly.  I’m sharing the gist of them here because they are good questions and I’m sure the info will be helpful.  All personal details have been omitted for privacy reasons.  If you have a question, feel free to send it on over and I will do the best I can to help.


Q:  I would like to make dinner plates and salad bowl out of green wine bottles. Most of the projects I see on your blog are only using one bottle in them. Can I use multiple bottles to make a bigger plate 10″-13″?

A:  I do try to focus on single bottle projects because they are the most predictable.  You should be okay if you use all the same brand of bottles.  If you can get ones that have matching factory and line numbers (molded into the glass on the bottom of the bottle) that indicates they are from the same batch of glass, which is even better.

So, after saying that, be prepared for some failure.  Since we don’t know where the bottles were made, or what the ingredients are, there will undoubtedly be some that just don’t work together.

I’ve had very good luck with fusing multiple Jameson whiskey bottles.

Q:  Hi Jody! I fused about 5 broken pieces of a plate that I got at a dollar store..the pieces were about 3-4″ wide,(cut in to rough circles)-glass is a bit thinner than 1/4 ” The pieces were stamped with shell designs, maybe this means they were cast…just an inexpensive plate. I treated the glass pieces as tho they were float and mixed them with float window glass (sort of used as a base for the pieces) and some float from Yogiheiny glass (have no clue how to spell the word!) Schedule was:350-1100×20″ then 200-1250 x 15″, then full -1510 x20″ then full -1035×1 hour then 150-700-to off. did not open kiln until under 100 degrees. My circle was fine for about 4-5 days-no cracks, etc So then I slumped in to a 10″ plate at : 250-1100 x 45″ then 250-1385×8″ then full to 1035 x1.5 hours then 100-940×5″ then 200-650 to off. Coming out of the kiln with a long crack (broke apart) just off center from the edge, then the next day broke into 2 other pieces. Can’t seem to see if cracks were related to the plate , the yogioheny (that word again) glass or the window glass…. Do you think the plate could have been another COE? Is the firing schedule too weird? Any ideas?

A:  I can say with absolute certainty that it is a compatibility problem.  As you know, it’s impossible to measure CoE outside of a lab setting, so I have no way to know what the CoE of the dollar store plate is.  However, I have used a bunch of plates like that, usually from the thrift store.  What I find is that the glass behaves more like fusible glass than float glass.

That is not to say that it is compatible with fusible glass, I have no way of knowing that.  And then add in a third CoE in the form of Yougheny (I don’t know how to spell it either), and you have a recipe for breakage.

There are two ways that I know of to get around mixed CoE’s.  One is to grind the glass down to a fine frit (sugar size)  mix it and fuse/cast it back together.  This works because you have reduced the surface size of the individual pieces down so small, and made a homogeneous mixture that even if the tiny individual grains expand away from each other, there is a matrix of pieces that have the same compatibility and it will generally be okay.  I’m working out the outer limits of this process, and finding that 1/8″ pieces are too big, there is serious compatibility cracking.

The other is to mix similar CoE’s together in a pot melt and form a new piece of glass with a unique CoE.  This only works on similar CoE’s, like float and some bottles.  Float and bottles are around 82-84 (again, no way to know for certain) if you add in a piece of fusible glass, say 96, it won’t work.  Even then, pot melts are temperamental.  I recently did 17 pot melts in a row with the same glass mix, only one worked.  blergh

So, in a fusing situation, it’s best to use each piece of glass individually.  The float by itself, the shell plate by itself, and the Youghiheny by itself.  You could try testing the glass from 2 dollar store plates together, if they are identical plates, chances are they came from the same factory and used the same glass.  If they are totally different, probably not.  Maybe, but probably not.

For someone coming from a fusible glass background, this can seem really limiting.  The trick is to recognize that there are so many things you can do to those individual pieces of glass and you can expand your creativity in a different direction.

I hope that helps and doesn’t totally discourage you.  I wish I could give you hard and fast rules, but there are just so many variables with recycled glass that it’s journey and a learning experience every day.

Q:  Firstly I found your site this week and am hooked, having a week off work I now have a queue of pieces for the kiln and another backlog of ideas in my mind. I am interested in using ‘found items’ as moulds and formers but am unsure what is suitable for the kiln. Unglazed ceramics and stainless steel I am familiar with, but what other metals? My friend does welding and could create shapes for me if we knew what was viable.

You can use black steel (untreated steel) forms in the kiln as well.  They will spall and peel badly, so I suggest using a fiber paper or thin-fire separator between the glass and the steel.  That being said, what a great thing to have a friend like that!  The possibilities are endless!

I’ve been told (and I believe it!) to avoid galvanized steel, as the chemicals used for the galvanizing process are extremely toxic and can be released during the firing process.

You can use copper, although it gets very soft and oxidizes badly.  I’ve had very good luck building webs of copper wire with fiber paper stapled over it and then slumping glass through it.  Stainless steel wire would work better, but I tend to use whatever I have at hand.

Another good resource is The Complete Metalsmith by Tim McCreight.  This is a great reference book for glass people, it lists all the melting temperatures for different metals, it’s easy to check and see if a metal will survive glass temperatures as well as being generally fascinating.  Also some really good across the board casting info.

I have also had very good luck building molds using Armstrong Industries Ceramaguard Ceiling tiles:

I had to special order an entire case from the builders supply store (Lowe’s in this case), which was not inexpensive, but I’ve been using it repeatedly for the past 8 years and have fired each one many, many times.  The tiles can be cut with a saw or razor knife and shaped.  Then kilnwashed and used for slumping, or dams, or anything else I can dream up.

If I think of any others, I’ll send them over.  So glad you like the website.  When I started out, there was NO info, it was pretty discouraging, so it’s great to hear that what I’ve learned helps other artists.