Kiln working glass is becoming an increasingly popular medium, but even though you may have seen a lot of fused glass art, how it’s done may still be a mystery to you. Truly some of the process to this day still seems like magic to me, but really aside from designing a piece, the art is very technical. There are three distinct types of glass fusing that are determined by the temperature the glass is heated to. A Soft Tack Fuse is heated between 1350° F and 1400° F, a Hard Tack between 1400° F and 1450° F, and a Full Fuse between 1450° F and 1550° F. Today I’m going to illustrate the Hard Tack Fuse with photos and helpful tips. The finished piece of a Hard Tack should be slightly contoured, the edges will laminate or smooth out so the cut edge is no longer sharp, and the piece will be permanently bonded together. With a tack fuse the integrity of each individual cut of glass is left in tack, so the beautiful textures are accentuated, which is part of the beauty of this type of fuse.
The first and most important thing about any type of glass fusing is that you use compatible glass. All glass heats at a specific rate and cools at a specific rate, which is referred to as the C.O.E. The C.O.E. or coefficient of expansion of the glass you are using needs to all be the same. If you try to fuse incompatible glass together the two different types of glass will reject each other, stress, and ultimately fracture. Almost as important as using compatible glass, is making sure you’ve prepped your kiln shelf. I’ve prepped my shelf with Bullseye Thinfire Shelf Paper. This is going to keep the glass pieces from fusing themselves to your ceramic kiln shelf. Feel free to use shelf wash instead of shelf paper if that’s your preference.
Secondly, pick out colors of compatible glass you want to work with. In the batch of tack fused pieces I’m illustrating I’ve cut out pieces for pendants, earrings, and bracelets. If you decide to use dichroic glass in your project, be sure to score the dichroic glass on the back or non-dichroic side. If you score your glass on the dichroic plane you run the risk of chipping off some of the pretty dichroic coating, which can result in a sloppy looking finished piece.
Next, stack your glass pieces exactly how you want them to melt together. I use Bullseye Glastac to hold my cuts of glass in place to make it easier to move my project to the kiln. Another thing to mention here about dichroic glass if you happen to want to use it in your project, is that you can’t tack fuse two dichroic sides together. You can heat the piece correctly, but you’ll be able to pull your glass apart at the end of the fusing cycle. Layer your dichroic cuts facing away from each other.
Okay, now that you have your project designed and stacked you’re ready to move it to the prepped kiln shelf. Once you have the kiln loaded it’s time to add some heat those babies and let the magic begin. For small projects like jewelry I ramp my kiln to the fusing temperature as fast I can. Your desired fusing temperature for a Hard Tack Fuse is between 1400 F and 1450 F degrees. Once your kiln reaches this temperature hold the heat steady for 10 to 15 minutes. It’s that simple!
Lastly, turn off your kiln and let the piece cool in the kiln for approximately an hour. You never want to cool your glass piece too quickly as you could potentially, and likely thermal shock your glass piece which can crack it into lots of little pieces.
As always, thanks for reading and if you have questions, please get in touch with me! I am happy to help. Also, all the finished pieces are available for purchase if you’re interested!