Powder Wafer Problems

[Dione Roberts]

After reading through the archives about powder wafers I used a stencil and made a few simple dragonfly shapes. I sifted BE powder over the stencil onto a kiln washed shelf and fired 1285 DPH to 1285 degrees and held for 10 minutes. The result was great. The pieces were delicate and brittle but I was able to move them onto the piece I was making and fuse them in place. Since that first lucky try, all my pieces have been kind of hard around the edges but are powdery on the interior and I can't transfer them to another piece to fuse. I increased the temp to 1325 degrees and held for 10 minutes and still had no luck.

Should the wafers still look like powder or should they look like they have begun to mature? I felt the problem with some of my wafers was that they were too thin, but now even if I make them thicker, they still don't stay together. I would guess that I am making my wafers about 1/16 inch thick.

Any help would be appreciated!

Dione

[Paul Tarlow]

After reading through the archives about powder wafers I used a stencil and made a few simple dragonfly shapes. I sifted BE powder over the stencil onto a kiln washed shelf and fired 1285 DPH to 1285 degrees and held for 10 minutes. The result was great. The pieces were delicate and brittle but I was able to move them onto the piece I was making and fuse them in place. Since that first lucky try, all my pieces have been kind of hard around the edges but are powdery on the interior and I can't transfer them to another piece to fuse. I increased the temp to 1325 degrees and held for 10 minutes and still had no luck.

Should the wafers still look like powder or should they look like they have begun to mature? I felt the problem with some of my wafers was that they were too thin, but now even if I make them thicker, they still don't stay together. I would guess that I am making my wafers about 1/16 inch thick.

Any help would be appreciated!

Dione

What is the configuration of elements on you kiln -- the "hard around the edges and powdery in the middle" sounds like what one might see if using a ceramic kiln (no top elements).

You might want to try evening out the temps by slowing down for the last 100 degrees or so. Also, different colored glasses soften at different temps (black, for example, softens long before white does). I've found this to be especially true and have had to accomodate different colors with slightly different schedules.

- Paul

[Dione Roberts]

I have a 23" octagon Skutt with elements in the lid as well as the sides. I will try slowing down for the last 100 degrees. Does it sound like I am going hot enough?


Thanks!
Dione

[Lynne Chappell]

If they're not sticking together, then you're not going high enough. If you're watching the firing then you can probably tell when you've reached the optimum point. The powder should be a little bit glossy. If you go too high then the edges will start crawling in and distorting. You usually want to go to the same temperature you would for a minimum tack fire. In my kiln that would be 600 DPH to 1375, hold 5.

[Terry Ow-Wing]

maybe the depth of the powder is too uneven?? This may produced cooked edges and uncooked centers?? if so try to really apply the powders evenly - of course I've only done this technique 3 times.

best of luck
- Terry O.

[Bob]

Hi Dione,

Everything you have done sounds correct and I would suggest a couple of minor tweaks to your firing schedule. You want the wafer to hold together when handled , but not be so overfired that the pattern is distorted and wrinkled. The hotter the kiln the more likely that the wafer will curl and distort due to contraction because the wafer is less than the equilibrium thickness of glass.

What I look for is the powder to start developing a darker colour and slightly "glassy" lustre. If it gets really "glassy" then you have gone too hot and the wafer is likely to be distorted.... this can be a good thing and I sometimes do it intentionally. If the surface of the wafer that was against the kiln shelf is still loose and powdery after firing then fire a bit (10 deg F) hotter. You can tell if the surface is powdery by gently rubbing the surface and checking for a gritty feel because the grains are lifting. Don't rub too much... because you can still use these wafers.


Your kiln might be slightly off in temperature calibration and about 10 degrees can make a big difference in making wafers.

I suggest that one other reason your later sets of wafers didn't fire completely was because you were using a colour that has a slightly higher melting temperature. White, Driftwood Grey (aka Ivory), and French Vanilla melt at higher temperatures. Black melts at the lowest temperature. Since the intention is to fire just hot enough to hold the powder together, it is important to take the melting temperature of the glass into account. Try doing a predominantly white wafer and a second mainly black wafer together in the same firing and see what a difference a few degrees makes in the firing.

A long winded way to say move your schedule up a few degrees and it should work fine. Hope this helps.

Cheers,

Bob

[Dione Roberts]

You have all hit on things that tell me where my problems lie. I know I'm under firing and I know that my my wafers are an uneven thickness. I'm also mixing colors that might have different melting temperatures. I will try again this morning and see what happens.

I'm glad I asked you all for help!

Thanks so much.
Dione

[Dione Roberts]

I wanted to let you all know how much you helped me with my powder wafer problem. I tried a new batch and made them a bit thinner and fired them at 600 DPH to 1345 degrees and held for 5 minutes. The results were very different from my past results. The wafers had a glossy look and I could handle them quite easily. I may have over fired a bit so I will back the temperature down a bit.

My result was not as good as the beautiful leaf I saw in an earlier post but I was happy none the less.

Thanks all!

Dione