Delphi Mold Disaster- Suggestions please :) - WarmGlass.com

Delphi Mold Disaster- Suggestions please :)

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Renee Inman
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Joined: Fri Jan 01, 2016 12:02 pm

Delphi Mold Disaster- Suggestions please :)

Postby Renee Inman » Fri Jan 01, 2016 1:44 pm

I've included a photo of my disaster and the instructions/firing schedule I used. I did not use an impression on my project. Followed Delphi's firing schedule and used 90 COE glass throughout. My plate ended up with "holes" in 3 out of 4 corners. Next time I use this mold I will try:

Check to make sure mold holes are clear
Use kiln posts to raise the mold for better circulation
tack fuse the two bottom glass pieces together before final firing

Hoping someone with more experience will have some suggestions to share. Thanks in advance for sharing your expertise!
Attachments
glass mold_Page_1.jpg
glass mold_Page_2.jpg
Delphi mold.jpg

The Hobbyist
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Location: Sun City West (NW Phoenix), AZ
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Re: Delphi Mold Disaster- Suggestions please :)

Postby The Hobbyist » Fri Jan 01, 2016 2:51 pm

You must put in two pieces of sheet glass!

Jim "The Hobbyist"
"With or without religion, good people can behave well and bad people can do evil; but for good people to do evil—that takes religion. " Steven Weinberg

Renee Inman
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Joined: Fri Jan 01, 2016 12:02 pm

Re: Delphi Mold Disaster- Suggestions please :)

Postby Renee Inman » Sat Jan 02, 2016 2:30 pm

Yes, I used two pieces of sheet glass. That's part of what made the outcome so surprising. Any other thoughts/suggestions?

linn keller
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Joined: Mon Mar 10, 2003 12:22 pm
Location: south tx

Re: Delphi Mold Disaster- Suggestions please :)

Postby linn keller » Sat Jan 02, 2016 9:16 pm

Hi,
Is it possible that you didn't put enough frit in the rim section? It looks like your glass is covering alot ( or all) of the entire rim base and depending on the size of the sheet glass, it could be that it stretched too much down and that made it too thin right by the corners. But that's just looking at it - I have no direct knowledge.
Linn
linn in deep deep south texas

FlorianFranken
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Joined: Thu Feb 12, 2015 11:08 am

Re: Delphi Mold Disaster- Suggestions please :)

Postby FlorianFranken » Sun Jan 03, 2016 6:08 am

It looks like you put the impression tile under the glass instead of on top?

Emily Speight
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Joined: Sat Dec 17, 2011 3:07 pm

Re: Delphi Mold Disaster- Suggestions please :)

Postby Emily Speight » Sun Jan 03, 2016 7:54 pm

holes like this are either a volume issue or an air escape issue.

I'm not convinced that all delphi's products have fuser's best interests in mind.

the provided schedule doesn't include a bubble squeeze, which you'd need if you didn't have a pre fused solid blank for the bottom. Also, looks like you're using the stringer/confetti glass, which if I'm not mistaken (I work with 96, so I'm not 100% familiar with all the 90 glasses) would probably be 'bumpy' which if you capped it with clear (ie the confetti glass was closer to the mold) might encourage bubbles.

So yeah - make sure the mold holes are clear, make sure the mold is elevated, pre fuse a solid blank - and see if that doesn't fix your problems.

Jerrwel
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Location: Charlotte, NC

Re: Delphi Mold Disaster- Suggestions please :)

Postby Jerrwel » Mon Jan 04, 2016 3:58 pm

Morganica wrote:I'm not entirely clear what you were trying to do? What was the end result supposed to be?


Emily Speight wrote:holes like this are either a volume issue or an air escape issue. .....................So yeah - make sure the mold holes are clear, make sure the mold is elevated, pre fuse a solid blank - and see if that doesn't fix your problems.


Emily Speight wrote:So yeah, in this case probably not annealing long enough. I think there's too much going on with the whole mold & texture imprint thing to anneal for only 45 min. Plus, the bottom got pretty thin, which would add stress.


It is unfortunate that there are two threads about Delphi molds and similar projects on the board at the moment. With all the variables associated with fusing, it is impossible to conclude what happened in these two instances as Delphi undoubtedly tested their products and projects extensively to work when all things are equal. I have a feeling all things are not equal in these attempts to use the products which is to be expected given kiln and glass variables. Since both projects appear to be using fracture/streamer glass and frit, it might be an expensive learning experience.

My first impression is that these projects are rather advanced as the following issues are present:
(1) glass volume;
(2) project element expansion;
(3) additional, non-typical stress;
(4) variable glass thickness.

(1) As Emily noted, glass volume can be an issue in these projects; assuming that the air holes are clear, this is probably the reason there are gaping holes in both projects. Bullseye's 'Kilnformed-Container' lesson http://www.bullseyeglass.com/education/lessons/kilnformed-container-164.html is similar to this project as relates to air escaping.

(2) While only one of these projects used the impression mold lying on top of the glass, the impression mold affects expansion both in the mold itself and glass shielded from heat by the impression mold. The heating, annealing and cooling phases of the firing schedule may be impacted. Graham Stone in his book, 'Firing Schedules for Glass,' suggests adjusting the firing schedule to a schedule for thicker glass to compensate for this issue; Bullseye's thick slab annealing chart http://www.bullseyeglass.com/images/stories/bullseye/PDF/other_technical/bullseye_annealing_thick_slabs.pdf is a good resource for developing the annealing portion of the firing schedule; the .75-inch schedule would be minimal for these projects IMHO.

(3) Related to item (2), the impression mold adds stress by creating the potential for uneven heating/cooling of the underlying glass. The project is prone to break due to this stress in either the heating, annealing, or cooling phases (see annealing comments in (2)).

(4) Proper annealing is essential when uneven glass/mold thickness is introduced as the project temperature must remain fairly constant across the entire project to avoid breakage (see annealing comments in (2)).

Most if not all of these issues are addressed in Brad Walker's book, 'Contemporary Fused Glass,' http://www.warmglass.org/books. This book steps the learner through a series of increasingly complex projects and is a great reference.
Jerry

Renee Inman
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Joined: Fri Jan 01, 2016 12:02 pm

Re: Delphi Mold Disaster- Suggestions please :)

Postby Renee Inman » Sun Jan 10, 2016 12:54 pm

Many thanks to everyone who contributed here! You've shortened my learning curve tremendously!


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