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tack fusing 4 layers 3mm without dams to keep the volume

Posted: Sat Mar 18, 2017 4:51 am
by seachange
Hi

Is it possible to tack fuse 4 or 5 layers 4x4" of 1/8" BE at a low temperature so the block holds together as a blank for a drop ring, but does not spread?

I work mostly with 2 layers, have no experience if this would be possible at all.

I imagine this would save a lot of time in having to dam each block to avoid the spreading of the glass.

Have tried to make drop vases by layering the glass on the drop ring without pre-fusing a blank. Quite a bit of air gets trapped between the layers - in spite of all the chads. Results are - for me - like a lottery, I loose most of the time.

Any helpful tips regarding firing schedule?

If you think this could work I will make some tests with 3mm tekta (have the most "waste glass" for tests), some guidance to avoid big disasters will be lovingly received.

Many thanks for all your help, seachange

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Sat Mar 18, 2017 12:03 pm
by Kevin Midgley
Having made crazy vases in the past, I understand the need for elimination of variables.
Hate to suggest it but handmade glass has variables you may not be able to account for.
I'd be using a machine made glass to reduce that number of variables possibly Spectrum if you are having issues with them.

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Sun Mar 19, 2017 1:38 am
by seachange
Thanks Kevin for your reply.

Having made a few test vases (most came out good), I am trying to make more a bit faster.

The actual drop process is not a problem, I can program the kiln to be ready for me to start watching the drop when I get up in the morning, and I don't mind doing this part one by one.
In reality have to do the drops one by one in my smaller kiln, it is the only kiln I have that has sufficient height.

Where I'd like to save some time is in the previous step, when I make multiple blanks in my large kiln. Having to dam each block (dams, fiber paper strips etc) takes extra time.

If I could fuse multiple blocks of 4 or 5 layers of glass to a point where they make a sufficiently good blank for the drop mold, but just before the point where the glass starts spreading out trying to become 1/4" high, it would save me a lot of set up time. Need to keep the 1/2" height for the drop.

I wonder if someone has some firing schedule guidance to achieve this, or has tried it and found it is not possible.

Thanks again, seachange

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Tue Mar 21, 2017 1:15 pm
by Jerrwel
seachange wrote:Hi

Is it possible to tack fuse 4 or 5 layers 4x4" of 1/8" BE at a low temperature so the block holds together as a blank for a drop ring, but does not spread?

I work mostly with 2 layers, have no experience if this would be possible at all.

I imagine this would save a lot of time in having to dam each block to avoid the spreading of the glass.

Have tried to make drop vases by layering the glass on the drop ring without pre-fusing a blank. Quite a bit of air gets trapped between the layers - in spite of all the chads. Results are - for me - like a lottery, I loose most of the time.

Any helpful tips regarding firing schedule?

If you think this could work I will make some tests with 3mm tekta (have the most "waste glass" for tests), some guidance to avoid big disasters will be lovingly received.

Many thanks for all your help, seachange


Two things come to mind:
(1) Why is building dams such a problem? I use ceramaguard as a shelf and as dams nailed or screwed to the shelf as forms for repetitive projects; use stainless steel screws and nails to avoid fuming zinc from galvanized steel. The ceramaguard does tend to deform after multiple firings; I put supports under the interior of the shelf to minimize distortion.
(2) Some time ago there was a project in the Warmglass online gallery (miss it so) that was created in one, combined firing for tack fuse and drop ring. There was not very much discussion about the process except that it was a real challenge. It would seem to this less than expert fuser that heating the project to a low tack fuse as specified by the manufacturer and holding for a time and then firing slowly to the drop temperature should accomplish in one firing what you are doing in two firings; talk about saving time! The critical issue is probably the span of the drop so that the glass does not drop at fusing temps.

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Tue Mar 21, 2017 1:15 pm
by Jerrwel
seachange wrote:Hi

Is it possible to tack fuse 4 or 5 layers 4x4" of 1/8" BE at a low temperature so the block holds together as a blank for a drop ring, but does not spread?

I work mostly with 2 layers, have no experience if this would be possible at all.

I imagine this would save a lot of time in having to dam each block to avoid the spreading of the glass.

Have tried to make drop vases by layering the glass on the drop ring without pre-fusing a blank. Quite a bit of air gets trapped between the layers - in spite of all the chads. Results are - for me - like a lottery, I loose most of the time.

Any helpful tips regarding firing schedule?

If you think this could work I will make some tests with 3mm tekta (have the most "waste glass" for tests), some guidance to avoid big disasters will be lovingly received.

Many thanks for all your help, seachange


Two things come to mind:
(1) Why is building dams such a problem? Using shelf paper as a separator, I use ceramaguard as a shelf and as dams nailed or screwed to the shelf as forms for repetitive projects; use stainless steel screws and nails to avoid fuming zinc from galvanized steel. The ceramaguard does tend to deform after multiple firings; I put supports under the interior of the shelf to minimize distortion.
(2) Some time ago there was a project in the Warmglass online gallery (miss it so) that was created in one, combined firing for tack fuse and drop ring. There was not very much discussion about the process except that it was a real challenge. It would seem to this less than expert fuser that heating the project to a low tack fuse as specified by the manufacturer and holding for a time and then firing slowly to the drop temperature should accomplish in one firing what you are doing in two firings; the trick is probably not allowing time for the glass to spread after the tack temps. Talk about saving time! The critical issue is probably the span of the drop so that the glass does not drop at tack temps. If you already know your drop temperature range, then based on the difference from the manufacturer's tack temperature range you will have an idea whether this process is plausible or not.

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Mon Mar 27, 2017 3:58 am
by seachange
Hi Jerry

Thank you for your reply. I hadn't thought of ceramaguard (have read about it but never used it).

The reason why I'd like to avoid using dams if at all possible is less set up time. No fiber paper strips, no kiln washing of all side surfaces. I have a coffin type kiln, with a 1" hardened fiber shelf. The surface is not perfectly smooth, but often good enough - depending on the project - to fire directly on it. Once in a while ( a long while) I lightly brush some alumina hydrate over the whole surface and smooth it with my fingers.

This fiber shelf gives me a large, seamless area on which to fire many blanks at once. Also at present I have very little storage space. Keeping pre-prepared ceramaguard boards to make the blanks for the different sizes drop rings would be quite a problem, until our new shed is done.

By the way I piled up 4x 3mm tekta triangles I had left from cutting circles and tested while firing other work, which goes to 730C. This gave me a solid tack fuse and kept the volume.

The only negative is that it held quite a few small air pockets in-between. These would have dissipated in a full fuse.

Next time will test the 4 layers with chads. Since I plan to cut off the rim of the vases, chads won't be a problem.

Regarding trying to do it all in one firing, in my previous tests the glass starts to drop at 677 C. This is using the smallest drop ring mold from BE. If I don't have a previously fused blank, the bottom layer of the glass pile starts dropping by itself and traps quite a bit of air, even when using big chads.

A long time ago I read about someone making lots of drop vases and never needing to pre-fuse a blank. So wish this would work for me too, but the "how to" eludes me :-k .

Many thanks for your help, seachange

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Tue Mar 28, 2017 12:59 am
by seachange
Jerrwel wrote:
seachange wrote:(2) Some time ago there was a project in the Warmglass online gallery (miss it so) that was created in one, combined firing for tack fuse and drop ring. There was not very much discussion about the process except that it was a real challenge. It would seem to this less than expert fuser that heating the project to a low tack fuse as specified by the manufacturer and holding for a time and then firing slowly to the drop temperature should accomplish in one firing what you are doing in two firings; the trick is probably not allowing time for the glass to spread after the tack temps. Talk about saving time! The critical issue is probably the span of the drop so that the glass does not drop at tack temps. If you already know your drop temperature range, then based on the difference from the manufacturer's tack temperature range you will have an idea whether this process is plausible or not.


Hi again Jerry

I think the project you refer to might be this one in the warmtips section http://www.warmtips.com/20060304.htm.

The gallery is gone, but the instructions are still there.

Cheers, seachange

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Sat Apr 01, 2017 1:20 pm
by jim simmons
I am the one that Brad got that information from.
I will look and see if I can find a pic of the drop vase made with this schedule.
If I can find it I will post the link.
The other Jim

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Sat Apr 01, 2017 1:24 pm
by jim simmons

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Thu Oct 12, 2017 3:44 pm
by Havi
Hi,
As much as I know, if you sift very thin layer of transparent powder between the layers
AND
go slow between 600Centigrade to 660/680 , 30 dph - you will eliminate air bubbles..

It works for me.


Havi

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Fri Mar 16, 2018 11:47 am
by Ed Cantarella
IF your pieces are round and of the right diameter, terra cotta saucers make great damns - I use 8" ones and make 4-5 layer stacks all the time.
Secret to using terra cotta: you need to fire it one time, at least 100 degrees hotter than you plan on going with your fuse. This is because terra cotta is often fired at relatively low temperatures and hasn't fully shrunk. Clay shrinks 5-8% when taken to full temperature - only little over half of it's shrinkage is during drying. TC isn't taken that high (a) to save money on the firing and(b) so the pores are not fully closed, so they breath better and can relieve water build-up in flower pots, even without a bottom hole.
If you don't pre-fire you will often get a nice blank of glass, but the TC will have cracked due to shrinkage. A thin strip of thin fire (pencil width) ran from edge to center will avoid bubble from trapped air under blank.

The tapered edge from the saucer? Plan your work so the wider part of glass blank is up, away from the drop ring. As the drop proceeds the edges generally pull slightly inward. If you damn it straight up the edge will tip from vertical - which is ok if you don't mind your underlayer showing that much but will be minimized by the slightly overhanging taper of the TC blank if you don't.

Other posts above have given all the reasonable suggestions on eliminating bubbles between layers. I personally prefer the "edge particles to allow the center to slump first, pushing air to edge" method over the "powder layer" method. YMMV I use medium -> course frit from one of the adjacent layers for my edge particles. I don't mind champagne bubbles but nothing bigger.

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Sat Jul 07, 2018 9:36 am
by FusedLightStudio
Ed, thanks so much for that great idea.

Do you just use kiln wash on the TC or do you cut fiber paper circles?

With the edge particles - how much of an edge on, say, a 6-inch diameter blank?

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Mon Jul 09, 2018 10:04 am
by Ed Cantarella
Kiln wash the terra cotta.
Small particles - course frit sized, maybe 3 or evenly spaced.

Re: tack fusing 4 layers 3mm without dams to keep the volume

Posted: Mon Jul 09, 2018 10:37 am
by FusedLightStudio
Ed Cantarella wrote:Kiln wash the terra cotta.
Small particles - course frit sized, maybe 3 or evenly spaced.


Thank you Ed!