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@SJLaun Re-strip is an excellent option for many projects, and should be installed between glass pieces following pattern lines as a continuous strip from border to border to gain the most strength. There are no absolute rules to providing support for glass art, as the overall panel size, number of pieces in the design, horizontal and vertical dimensions and how the artwork is to be hung or installed can all be factors in deciding how to reinforce your art.Reinforcement is generally installed spanning the shorter dimension, whether horizontal or vertical.Thank you for your insightful comments and questions.

@cesarnchj Using a quality stained glass solder and stained glass flux can both help to give you the most even, shiny silver finish possible on your glass art. If you have been using a rosin-core solder or flux from a hardware store upgrade to stained glass products - your art is worth it. Even using stained glass quality supplies you may occasionally see black flecks develop when soldering caused by impurities in the flux. Once you have finished soldering your full project, use a flux remover and scrub your art. The black coloration should wash away, and the solder lines should appear clean and brilliant.

@ Many homeowners opt to leave an existing window in place when installing a glass art sidelight or transom. The additional panes of glass can protect the art, add thermal insulation value, and help provide additional security for the home.When installing glass art next to an existing window it is ideal to maintain a small air space between panes and around the outside frame of the project to allow air to circulate, preventing moisture from being trapped where it will cause condensation. This can be achieved by using Cabinet Door Clips to install the panel or by installing small wood spacer blocks before capturing the panel in the finish trim.

@Memd913 While a 2' x 2' copper foil panel typically wouldn't require additional reinforcement, the extra strain from being installed horizontally warrants a bit of extra strength. You can opt to use reinforcing strip positioned between glass pieces from border to border through the panel or to give it a little heavier support by installing zinc rebar. The rebar should be attached standing "on-edge" from border to border, and soldered or wire-tied to the panel at each point it crosses a solder line, then soldered to the rigid came border on the panel. Many people find that using 2 pieces of rebar positioned evenly on the panel is less visible than a single piece positioned at the center.

@jhotka The exact temperature or rheostat setting to use with a 60/40 solder can vary, however many beginners find success using an iron with built-in temperature control such as the Studio 100 or Weller 100. Both of these irons come with tips that hold the iron at approximately 800 degrees F. If you are using an iron with a separate rheostat or built-in adjustable controller, you may need to try several settings before you find what works well for you.Finishing box corners can be a challenge for both beginners and experienced glass artists. To get the strongest possible construction, it is ideal for corners to meet without an overlap. The Professional Box Maker tool is helpful for achieving this position. The void space on the outside can be filled with a bit of copper wire or ball chain, then soldered to build up the joint.

@ There are a few common reasons that the glass may not have slumped as desired. The first factor is that although kiln controllers often include pre-set firing programs based on averages, each kiln can fire a little differently. The size of the firing chamber, the material the kiln is constructed from, and the calibration of the controller can all be factors. You may want to adjust the firing schedule to have a longer hold time at the top process temperature to allow the glass time to slump, or you may need to increase the top process temperature slightly.Another factor can be the shape of the mold and size and thickness of glass used. For some mold shapes it is ideal to slump glass that was initially fused in a dam mold, allowing you to create a glass piece that is thicker than the 1/4" average achieved by layering 2 pieces of glass. You may want to experiment and try using this slumping mold with 3 layers of glass to see if the extra material and weight help it to reach the full depth and shape of the form.Additionally, make sure the vent holes in the mold are not clogged with mold release. These tiny holes allow the air to escape so the glass can slump to fit the contour of the mold. Trapped air may prevent the glass from dropping, or can even cause bubbles to appear in your project.

@ Using pattern bar slices as a design element can create some unique and stunning art. If you wish to create a center motif of pattern slices with a border, there are a few considerations to make. First, how thick are the pattern slices? If they are about 1/4" thick, when full fused they should remain approximately the same dimensions. If they are thicker, the glass will flow outward a bit, or if they are thinner, the glass may pull in a bit. Many artists opt to cut slices a little thin, and position them on a layer of clear fusible glass to help stabilize the size and shape. Additionally, for the border the glass needs to be stacked approximately 1/4" thick, if you use a thin base glass, you can simply add a layer of color border over top to achieve this. If you wish to avoid using a base layer of glass, you will want to stack 2 layers of the border color to help ensure it fuses evenly with the center motif.

@ Boron Nitride spray works well as a release on stainless steel molds. Make sure you shake it well before use, and keep the can upright while spraying. The first time you treat the mold you will want to apply several coats of release.You do not need to use a kiln shelf in your kiln, however it is often recommended. The kiln shelf will protect the floor of your kiln by ensuring that if glass sticks to a surface, it's the removable and replaceable shelf that is damaged instead of the floor of the kiln. If you wish to fire without a shelf, be sure to use a fiber paper to protect your kiln floor.

@ The process of fusing relies on heating the glass to a semi-liquid state. Setting a lower process temperature to achieve just a tack fuse will allow you to maintain a fairly crisp square shape, however, if a contour fuse or full fuse is desired, the glass will be liquid enough that the corners will round and the glass will either pull-in or flow outward to achieve a depth (or thickness) of approximately 1/4". If you desire a full-fused look and a square shape your options are to use a mold or dams to contain glass to a square shape, or to coldwork the fused project.

Two things: First, the question did not specify which of the dimensions was horizontal or vertical. Is supporting rebar always "horizontal" or should it span the short dimension of the window? Second, I think the option of Re-strip needs to be addressed here, since many designs do not lend themselves to big straight lines of re-bar.