04 July 2011

Experimenting with Dalle de Verre

Okay. I procrastinate about some things... dishes, yard work, basement cleaning, vacuuming, bill paying, all those have been known to fall by the wayside if something else that is more interesting comes along... and for me almost anything is more interesting than those things.

But I have to say that wedding gifts are by far the thing I procrastinate over the most. But for an upcoming wedding (in two weeks) I thought I would get the gift out of the way before the last minute.

I decided to make a small dalle de verre mosaic using the scraps of left over glass that I took home to finish the mosaic I started during Verdiano's workshop at the Chicago Mosaic School.

It would not be a very big piece since I had relatively few scraps that would work for dalle de verre -- since I had chosen scraps for cutting the glass into shards and tessarae for the mosaic, not for dalle de verre work. Plus I assumed I would end up wrecking some of the pieces when distressing them because I was using a regular glass hammer instead of the Blenko hammer. So I planned accordingly...

In Sophie's workshop we talked about the fact that one side would always have the substrate and the glass flush with each other since we were gluing the glass to the plastic and then adding the cement. I hate being told that something "has" to be only one way... so I started thinking of other ways to do it. Then Kim mentioned putting clay on the top surface of the glass before adding the cement might help keep the cement off of the glass and make the clean up easier...

On the drive home from Chicago I was processing the workshop in my head and I started thinking that if instead of gluing the glass to the plastic, what if I put down a slab of clay and imbedded the glass in it... wouldn't that allow me to make the piece have glass that extended beyond the substrate on both sides? I needed to experiment and the wedding gift would be the perfect test...

We'd had problems getting the plastic flat enough in the workshop... it had creases in it where the manufacturer had folded it up prior to rolling it up, and those creases were impossible to flatten out. We ended up with ridges in the backs of our pieces. So I thought I would use contact paper as a working surface. It stuck to the plywood much better than the duct tape we used to tape down the plastic. Cool, I thought (important - remember this fact...).

So here's the clay form for the piece, with hanging wire installed and a clay slab ready for glass to be pressed into it.

Here it is with the glass pressed down into the slab.

I tried Kim's suggestion -- coating the top of the glass with a clay slurry to keep the cement off of the glass.

Ready for the cement.

At one point during the workshop Karen had pondered whether or not using concrete instead of the Kerabond/Keralastic mixture would work. Would it be stronger? We did not experience any substrate failures during the workshop, but some of the pieces were thin enough that Sophie had the students adding more cement... that got us to talking about strength and size...

So for this one I used Sherri Warner Hunter's concrete recipe... except it was too thick to pipe into the piece so I had to add more of the latex plasticizer additive than her recipe called for so that it would flow though a pastry bag... (important - remember this fact, too). I also colored the concrete blue using Tints All...

After filling the piece half way I added reinforcement wire. I did not add mesh since the spaces were so small... (another important fact to be remembered).

I added more cement.

And covered it with plastic to cure overnight...

All went well when I peeled the clay off the sides. The concrete seemed very hard, but still workable. When I tried to lift the piece off of the clay slab I ran into trouble...The clay and the concrete really liked each other and refused to come apart... since I covered the plywood with contact paper which was firmly stuck down I couldn't cut it loose from the plywood either... I decided to pull the contact paper off of the plywood and then peel it  -- and the clay -- off the back of the piece.

Didn't work all that well...

Was it because I used concrete instead of cement? Was it the Tints All and/or the extra plasticizer that I added to the concrete? Was it the fact that I only added wire for the reinforcement instead of wire and mesh? Would this have been avoided if I had worked on plastic (which I could have cut loose from the plywood and peeled off the back)? Or was the entire clay slab idea the problem and doomed to fail?

Round 2

Determined to make this work I crumbled the concrete away from the glass (which the ease in doing this makes me think I screwed the concrete up) and gave the glass pieces a vinegar bath. Ditto with the hanging wire.

I remade the form, with the clay slab, but this time I put it on plastic that had been stapled to the plywood... just in case. I inserted the hanging wire and imbedded the glass.

On a couple pieces of the glass I added clay boosters so that the glass would all be the same height on the front side. Since I was working with scraps I was pretty limited with the pieces I had. I thought that the boosters would make some of the glass inset and some extended on the back side -- maybe -- worth trying in any case.

This time I added both mesh and wire... I know, I know, I'm changing too many variables to make this a good experiment, but I really wanted this to work this time.

Once again I wrapped it in plastic and set it to cure overnight.

This time the experiment was successful -- mostly... I think I would not use the boosters again -- and I would not need to anyway if I wasn't using scraps of glass -- but for this project I think I can live with it. If I do use them again I will be more deliberative about how I construct them.

As you can see in these three images, the piece stayed together (in part because I made the clay slab thick enough that I could use a pot cutting wire to lift the piece up off the board)and the glass does extend beyond the substrate on both sides giving me a nice front and back to mosaic



I wrapped the piece up to let it cure for a few more days. Then I'll do a more thorough cleaning and mosaic it.  I have a lovely blue-gray marble and a gray-white travertine...

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