Slumping issue....1st post - WarmGlass.com

Slumping issue....1st post

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Scott Walter
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Joined: Fri Sep 08, 2017 2:25 pm

Slumping issue....1st post

Postby Scott Walter » Tue Sep 12, 2017 6:14 pm

This is my first post so forgive me if this is the wrong section to post in....i am having some issues trying to slump mason jars that came with my house. My firing schedule is:

300dph...500f....12mins
300. 750. 12
300. 1100. 10
200. 1300. 20
250. 1475. 10
9999. 1100. 60
500. 970. 30
120. 250. 20

The first 3 segments were 500dph. I lowered the dph to 300 and I still got poor results. I got the schedule online. Each time (tried three times) I get bubbles and the lettering is not clear. Any clue how to fix this? I have an Olympic kiln and using bullseye wash. I am really talking about the big bubbles toward the top of the jar.

Thanks for any help.
IMG_20170912_181050.jpg
Slumped mason jar

Valerie Adams
Posts: 587
Joined: Mon Apr 19, 2004 2:49 pm
Location: Santa Rosa, California
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Re: Slumping issue....1st post

Postby Valerie Adams » Thu Sep 14, 2017 12:53 pm

I have a strict 'no bottles allowed' policy in my studio but awhile back found myself with a couple cases of those new 'vintage' look jars in green and blue. Because they're not tall and have a large foot, I sawed them in half vertically. That way they slump quite nicely, due to less mass. Of course, half of them don't have any writing on them, but for spoon rests or soap dishes, people didn't mind.

Judd
Posts: 290
Joined: Mon Sep 01, 2003 9:45 am
Location: Arkansas

Re: Slumping issue....1st post

Postby Judd » Fri Sep 15, 2017 10:03 am

I think you're firing too hot for just slumping. I hit 1350 for a float glass slump.

Scott Walter
Posts: 2
Joined: Fri Sep 08, 2017 2:25 pm

Re: Slumping issue....1st post

Postby Scott Walter » Fri Sep 15, 2017 2:59 pm

Thanks for the replies, so if I'm firing too hot, am i also firing too fast?

I'd like to lose the bubbles.

On side note am I really supposed to Kiln wash every single time I fire if I go above 1100 degrees? I think the instructions if I recall correctly so that if you fire above 1100 or maybe 1200 degrees, you need to reapply Kiln wash each firing.

Thank you for the input.

jim simmons
Posts: 441
Joined: Sun Mar 09, 2003 10:37 pm
Location: Hillsboro Oregon
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Re: Slumping issue....1st post

Postby jim simmons » Sat Sep 16, 2017 1:19 pm

Absolutely
The other Jim

Judd
Posts: 290
Joined: Mon Sep 01, 2003 9:45 am
Location: Arkansas

Re: Slumping issue....1st post

Postby Judd » Mon Sep 18, 2017 9:40 am

I kiln wash once a month, or so, I never remove the old wash because I like the texture I get on my glass.

Ed Cantarella
Posts: 151
Joined: Mon Feb 26, 2018 3:49 pm
Location: Highland, Michigan, USA

Re: Slumping issue....1st post

Postby Ed Cantarella » Tue Mar 13, 2018 8:24 pm

Some bottle and jar shapes will almost always form bubbles, has a lot to do with their shape. E.g. Bordeau wine bottles(no hard shoulder where it goes to neck) will usually slump down with no bubble - at least at the neck. Bottles with a "harder" shoulder(transitions quickly from the bottle cylinder to the neck will almost always have a bubble, in sort of a bow-tie shape. When slumping bottles or jars one must analyse the size of the bottom - the bottom is going to ALWAYS fall toward the body of the bottle(even if you tip it up you can't avoid it, the greater body of glass in the body wins that fight), so you have to understand the bottom is going to swing toward the body as far as it is wide. Which is why wide bottom bottles are pretty meh for slumping, since half the item is taken up by the bottom which has fallen onto it. Larger bottles have the additional issue that their body isn't much thicker than a small bottle, so the bottom tipping over often creates two more bubbles to each side of the bottom(once slumped over) that will be thin, or will even POP! Nicest bottle in the world for a cheese tray, IMHO :) is a Brennan's Irish Cream. The bottle is wide, the bottom is shallow from front to back. Makes a nice cheese tray that could actually hold a 1 lb. cheese ball and a few apple slices or such.

Mason jars need to be crushed(ok, slumped) in a brutal conflagration with a target of 1460 f or so, held for 30+ minutes, to get anywhere flat-ish. And never waste your time on a Crown Royal bottle - between ridges and the bottom it is a useless activity no matter how cool they look pre-kiln. We started with bottles and bought several hundred off strangers. And then we(wife & I) committed to more artistic stuff and threw them away. And then the kilns did something while we weren't looking and multiplied. :mrgreen:

P.S. Square A-1 steak sauce bottle - flatten one of those for the cutest butter dish EVER. :lol:

P.S.S. Some people are ok with the bottom just slumping over - I could never abide with a bottle or jar slump where the bottom didn''t fuse fully with the body. Having a gap or crack there just seemed like a place for food and such to get stuck. Food poisoning - NO!
HER last words were, "I'm melting, melting . . . " Dissenting opinions generally welcome for comic relief or personal edification. Sometimes both.


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