WarmGlass.com

I am in the process of slumping a Passover Seder plate on the ceramic mold and for the life of me I can't find my notes on slumping temp etc. I know I wrote it down but of course I can't remember where I put the darn thing. Can anyone help me with the process?
Thanks in advance,

Peter Brown

The simplest possible slumping schedule is 250 to 1150 hold until slumped.
60 minutes is more than enough.

I normally slump most molds to 1210 hold 15 minutes. The Seder plate mold has deeper holes and I know it's more than 1220 but not sure how much to not distort the bottoms of the indentations.

Thanks.

There are two ways to slump--high and fast, i.e., go to a hotter temperature for shorter times, and low and slow. Increasing the temperature usually isn't as effective as increasing the time.

You'll have a lot more control over plate indentations if you follow Brock's suggestion, i.e. stay under 1200F but increase the time and WATCH. When the slump is nearly perfect, kick in the downramp and start the anneal. The residual heat will take it the rest of the way.

Yikes - I bought the same mold! (picture attached - I hope) It is too late to return it and get a different one with nice, polite cups, so I would appreciate advice. I understand the part about slumping slowly - 250 to 1150 and hold until almost perfect. My questions are a bit different, so would you more experienced folks kindly suggest how I might accomplish my goals?

Approach I would like to decorate the cup bottoms, but I'm worried that if I place decoration on the round blank, the decoration will not "land" inside the cups during the slump process. I was thinking of making a pencil tracing of the mold on a piece of paper and then using the tracing to place the design elements. Is there a better way?

Durability I expect this masterpiece to become a family heirloom ( ) so how will durability for the ages be affected by having most of the top left as one layer? Making the whole thing two full layers would involve cutting lots of cup holes or adding lots of frit to the top. I plan to make the cup bottoms thicker than the rest of the plate. My naive plan is to make the cup decoration (various frits and some paint) a bit thicker than 1/8" and affix the decor to the 10" blank in the strategic places. I will full fuse at this point. I also want some texture, so I plan to decorate the edge with a border that will add 1.5" to the total diameter. The border will not be perfectly round - more organic (wavy-ish). This leaves a big plain section in the center, plus the flat parts surrounding the cups, which I don't really want to gunk up with a lot of clutter. So, do you think it will be okay to leave the flat parts as one layer? If I leave them as one layer, do you think that my 10" round blank (with the cup decor) will become distorted during the full fuse? If so, by how much? If you think the border will compensate for the distortion, I will be happy.

Thank you in advance for your thoughts.

Franzeska,
1/8 is too thin to be durable. It will also contract during your first fuse. I would cut two circles the exact diameter of your mold. Use your tracing to place your designs. Full fuse them together. Make sure that any "glass paint" that you use can stand up to a full fuse (1450-1500 f.) If you want your designs (in glass) to be raised, first full fuse the two blanks and then tack fuse the designs on top in a second fireing, then slump.

Warren

I forgot to mention that I am using Spectrum glass for this seder plate project. Does the recommendation of 250 to 1150 still apply, or should my target temperture be higher, say 1200?? Also, the center of the piece is a bit thicker than the edges due to the design elements - but not thicker than 3/8 (more like 5/16).

Thanks

You can use Bullseye and Spectrum schedules interchangeably.

I sure hope someone is online now because I need advice.

My seder plate has been soaking at 1150 for almost 40 minutes, and it has not begun to slump. Should I be patient, or increase the temperature?

The smaller the span, the longer it takes to slump. Watch it, and if you have to raise the temp, then do. Keep notes on this firing.

Bullseye recommends 1180 - 1250 depending on the mold (this is based on 6mm thick glass). Their schedule is 300 - 1180 hold 5, AFAP 900 hold 1 hr, 100 DPH to 700, hold 1. The viscosity of the type of glass you are fusing (cathedral, opal, color), as well as the thickness, will impact the rate at which the piece slumps.

For deeper molds (they show the Seder plate and a 10" square slumper with a 1/2" drop) they recommend going as high as 1250 with a 1hr 15 minute hold, but caution overfiring. They recommend lower and longer to avoid this. You'll have to keep checking to see how the slump is going.

Wow! I have a whole page of notes with all the changes I have made. I won't be surprised if it is ruined, but I still hope for the best. Before y'all responded I tried raising it to 1200. Nothing after quite a wait. Then I went to 1225. After about 45 minutes it started looking soft, but again, nothing. I then went to 1240. After another wait, I can see some dimension. I'll be watching for another hour or so. If the result isn't too embarrassing, I'll post a picture this weekend.

I guess there is such a thing as too low...

Thank you for your advice.

Franzeska

Wow! It should not take that much time to slump a small plate .

You would be better off raising your top temp than keeping the plate in the kiln for HOURS!

Dana W.

This is not just slumping a small plate. This is slumping 6 small depressions inside a slump. The size of the depressions mandates a long slow slump.
Higher temperatures lead to improper slumping, hang-ups and possibly devit.

I just took mine out of the kiln. Not sure if I like the design, but it worked. BE glass, slumped at 100 F/hr to 1225 held for 35 minutes. It took a total of 26 hours. Low and very slow seems to work best in my kiln.

The cups dropped about 1/3 inch below the center and the overall height (from top of rim to table) is 1 inch. Thankfully it is stable on the table.

Hag sameach to all who observe Pesach and Happy Easter to most of you.

Brock wrote:This is not just slumping a small plate. This is slumping 6 small depressions inside a slump. The size of the depressions mandates a long slow slump.
Higher temperatures lead to improper slumping, hang-ups and possibly devit.

I realize that, but I don't think you're going anywhere with 1150 degrees unless it's a thicker piece.

And can you really get devit at slumping temps? No one is suggesting 1500 degrees.

Dana W.

I said, if you need more heat add it . . .
There are various problems associated with higher temp slumps, including devit.

JestersBaubles wrote:

Brock wrote:This is not just slumping a small plate. This is slumping 6 small depressions inside a slump. The size of the depressions mandates a long slow slump.
Higher temperatures lead to improper slumping, hang-ups and possibly devit.

I realize that, but I don't think you're going anywhere with 1150 degrees unless it's a thicker piece.

And can you really get devit at slumping temps? No one is suggesting 1500 degrees.

Dana W.

Bullseye tech note 4 Heat and Glass suggests the devitrification range is between 700ºC and 760ºC (1300-1400F)

SUCCESS!!!! This was my first slumped project. Zowie! Thank you everyone, for your suggestions, for your encouragement, and for your exchange of ideas, because everything that y'all wrote made me think about the various scenarios.

I had some 2" square conglemerations that were intended to be magnets for my office mates, but they turned out too large. I didn't know what to do with them, and I don't like to waste... So, I decided to try to center them over the seder plate cups (not so easy, even with my tracing because I decided to use a white blank under the amber transparent. I wound up measuring the jockeying the plate until I thought the design lined up with the cup centers. The design pieces had a tiny bit of devit from the original firing (or was it the 2nd firing), so I brushed a layer of Spray A on them. Plus, there will be (unappetizing) food in contact with the glass, so I thought that would add a safe layer. The extra little pieces were cut from a pattern bar (Patty Gray class in Fort Myers) and fused again on their side to add a little interest. The cups are quite well formed. The blanks were 11.5 inches and the finished plat is 11.25" (Did I measure wrong the first time, or did the slumping process drag everying in/down??).The thing weighs a TON - a bissel (little) over 3 lbs.

By the way, it was impossible to see the slumping progress. I finally gave up trying to see if any slumping had occurred. That all means that it may have slumped much sooner and at a lower temperature than I ended up with (40 min. @ 1150, more at 1200, more at 1225, then to 1240, and finally 1250 for 30 minutes). I'll have to make another one to really test the right schedule, but any subsequent tries will NOT have so much glass.

Here are the pix:

Lovely.

FWIW, the weigh of the glass probably helped with the slump

Dana