Drop ring formula??

daffodildeb · Post by **daffodildeb** » Tue Apr 13, 2004 4:39 am

Forgive me if this has been covered (I couldn't find it) but is there any kind of formula for drop rings? I just did one with 6" supports. The ring is about 4 1/2" across (too hot right now to get an exact measurement), and the glass is two standard thicknesses of Spectrum--wispy covered with Sys 96 clear--cut and fused to exactly fit. The drop went perfectly, except...it didn't reach the kiln shelf as I wanted, and it looks (again, still too hot) like it's very thin. I wanted something vase-like.

So, is there a way to relate thickness & height & diameter to get an idea of how thick the end result will be and to make sure it will bottom out on the shelf? Or is it just a matter of by-guess-and-by-golly?

On the good side, this is only the second one I've done (first one never dropped at all and was heavily devitted since it wasn't a fusing glass), and it looks pretty good.

Oh, one other thing--do you normally do a fuse first of the two layers, or just stack them and hope they stay in place?

Ooo--one more thing

(I sound like Columbo). I noticed some bubbles. I did 1275 for 25 minutes, and would have thought the bubbles would have released. Is there a magic formula for THAT?

Tony Serviente · Post by **Tony Serviente** » Tue Apr 13, 2004 8:24 am

Deb-Drop outs are very tricky. For a while I was doing ten at a time, with the same rings and glass, and each one was different, even accounting for different placement in the kiln! I have done them with up to four layers, and would combine the fuse and drop in the same firings, one of the few times we get to do that. The deeper the drop the thinner the top. The only way to get around that would be to design your blank so as to have less layers in the center of the ring, and more toward the edge. You will have to keep an eye on your drop, and freeze it when it looks good. Any schedules will be so kiln specific as to be useless to you, especially with drop outs. Just make sure you pay particular attention to kiln washing the inner edge of the form, as thats the big sticking point.

daffodildeb · Post by **daffodildeb** » Tue Apr 13, 2004 2:14 pm

Interesting. Now that it's cooled, I find that the piece is really thick enough on the sides (just not much color) but I still want to "bottom out." The ring portion is plenty thick. In view of this, have you ever put more glass in the CENTER--say one smaller diameter layer--so you can get thicker and more colorful sides. Or would that just cause a bad center drop? The main thing is I don't want the kind of piece that requires a support--I want something that is free standing. In fact, if it bulges a bit on the shelf I wouldn't be unhappy.

P.S. I have verified the ring size--4 1/2"

Tony Serviente · Post by **Tony Serviente** » Tue Apr 13, 2004 4:39 pm

I was doing hanging vases, so was not trying to have them touch. Adding weight to the center will accelerate the drop, elongate the shape, and thin the top and sides. If you want a nice flat bottom cook it longer or hotter, but if you let it go too long the top edges may get paper thin. You will have to find the right balance between a bulging base and thick enough sides to be safe to handle. If you go overboard, the bottom will grow to a diameter that exceeds the ring, and you won't be able to get it out. I would occassionally overcook one, and the infoldings at the base were very appealing. I still have on around just cuz I like to look at it.

Richard Dubois · Post by **Richard Dubois** » Sat Apr 17, 2004 2:43 pm

Any reason for the two layers? I use 4 for my 6" drops from a 5" inner diameter ring. Then the walls seem sturdy. If you watch the drop through the peep hole (or peek through the lid briefly) you can see when it hits the shelf and decide how flat you want the bottom to be.

Richard

daffodildeb · Post by **daffodildeb** » Sat Apr 17, 2004 9:04 pm

"They" said two layers, and also 6" drop. My 6" drop didn't make it far enough down by about 1" or so.

Did you prefuse the 4 layers? What kind of firing schedule did you use?

Richard Dubois · Post by **Richard Dubois** » Sat Apr 17, 2004 10:15 pm

I can't remember the "they" I got it from, but I use 2 layers for 2"-3" drops, and 3-4 layers for 6" (depends on the ring size).

I always do a full fuse on the disk to start, lately to 1500 (this is System 96). The slump is ramped to 1250, then I wait for the glass to drop as far as I wish (depending on wanting a flat or round bottom). So mine are indeed (at least) a two-step process. I assume you have schedules for both these operations?

Richard

daffodildeb · Post by **daffodildeb** » Sat Apr 17, 2004 10:17 pm

Yup, thanks for the info--can't wait to try it with 4 layers!

Richard Dubois · Post by **Richard Dubois** » Sat Apr 17, 2004 10:19 pm

One caution - make sure you have a decent size rim. With the extra layers there is a tendency for a narrow rim to fall through the hole! It appears to depend on the weight of glass hanging over the hole. Two layers allows a narrower rim than four.

Richard

daffodildeb · Post by **daffodildeb** » Sat Apr 17, 2004 10:22 pm

Do you have a recommendation? I am using a mold from Alpine--has a 1" rim, as I recall (I'm out of town right now and don't have it near).

Richard Dubois · Post by **Richard Dubois** » Sat Apr 17, 2004 10:27 pm

My commercial ring (don't know who made it) is a standard 9" outer, 5" inner. So there is a 2" rim. I think 1 3/4 to 2" seems needed with the 4 layers. I have a very pretty piece from having half the rim fall through

Richard

Tony Serviente · Post by **Tony Serviente** » Mon Apr 19, 2004 2:54 pm

When I was doing four layers I was not pre fusing. You can do the drop and fuse in the same firing. I did many dozens that way. You can also get some very interesting effects by stacking different shapes and colors.