drop vases - color density problems

[seachange]

Hi,

I am trying to make a black/white drop vase as a gift.

The blank is 4 layers of 3mm BE glass, 5" square, starting on the shelf:

Tekta clear
white
tekta clear
alternating strips of black and white.

Fully fused to 804C 1480F. Due to the full fuse and no dams the blank spread out to 6 1/4" (this is ok, I am experimenting and learning).

Had intented to drop 6" using BE smallest mold (8633, inside diameter 3" 8cm). However, because the blank got a bit too big, decided to use the next size ring, 8632, ID 4.9" 13cm.

Reduced height to 5" props.
Added 1 1/4" wide strips of tekta around the blank, to avoid it falling into the mold. As mentioned before, I am learning so was not sure if the blank was wide enough to stay in place.

Blank placed on the mold with the top - the black and white strips layer - now towards the bottom, so it becomes the outside of the vase. The mold covered with a ring of fibre paper with the whole cut 1/8" wider than the inner diameter of the mold.

Don't know if this is really necessary, I get a bit of a rough surface on the outside of vase and wonder if this is from the 2mm fibre paper. Had used it once before (in another failed attempt at a vase). Saw in the BE video that they disposed of the fibre paper ring after one firing. Thought it wasteful, but may be it is necessary to replace it for every firing.

It took 4 1/2 hours to touch bottom. I hold at 680C 1256F until it is ready.

As you can see in these pictures, there is still enough of the colored blank remaining on the flat rim (to be cut off). I thought this should have been enough reservoir of color to get more intense black and white from rim to bottom, but the top half of the vase is very diluted and transparent.

Have seen in the BE video that the glass stretches more towards the edges (close to the mold), and very little in the center. But all my research on the web seems to show that blanks are normally fused from 4 or 5 even size squares of glass (not by piling little extra strips of colored glass around the area corresponding to the inside rim of the mold)

My question is: how do I get enough color density on the top half of the vase? I really have no idea how to move forward from here.

Amanda Simmons is coming to Australia next year, I have registered for her class but that's 12 months to wait. Would love to be able to make this wedding anniversary gift (to be posted in September).

Many thanks,

seachange

vase inside

vase bottom

vase side - wide black strip on the blank

[Kevin Midgley]

too fast a firing would be my first guess.
That is why the bowls that are steep sided are fired with 3 different molds over 3 different firings.
The other way would be to get the magic temperature in your kiln that will allow it to move downwards but only slowly.

Or much simpler, drape the piece over a mold and then deal with the folds and the usual problems of the base not being perfectly flat.
Then you have the choices of lapping it flat and or gluing on a base.

Not only have you got no colour, you have super thin glass on the sides.....
Use stiff black perhaps but then you could have issues with the white's viscosity and compatibility.

I used to make 20" vases but they needed a stand.

[seachange]

Hi Kevin

Thanks for your reply.

Unless I have it wrong, I think I am following the rules of thumb for the thickness, 4 layers of 3mm glass for a 6" drop. Because of the size of the hole in the mold I reduced the drop to 5".

From previous vases where I have removed the rim, the thickness at the top is at least 2mm. Did my last tests in 2012, then life took over. Now I have talked to local artists who have taken drop vase classes from international teachers and they tell me 2mm to 2mm+ is the thickness they have on their pieces. (Unfortunately I missed those classes in Australia a couple of years ago).

At present I am aiming at drop vases that feel and look delicate, without being too fragile. Neither thick nor draped.

Regarding the firing schedule, I am using the top elements of my kiln only:

332F to 1256F . Takes 4 hours to get to 1256, and by this time it has already dropped close to 1". Then another 3 hours until it touches bottom shelf and flattens out a bit (i keep watching it).

I thought this schedule was a good balance between time spent and results. However it makes sense that if I have a slower firing then more glass will stay on the sides and the color will be denser. Perhaps dense enough. Will make another similar blank and test it.

Thanks, seachange

[Kevin Midgley]

suggestion here.
try using bottom element only and heat to perhaps 1175 only.
rather than trying to get a large flat bottom be prepared to make a stand or cold attach a base to it. It will be more stable that way anyway.
as for the 1175 the glass may not start moving. You will have to figure out the time and temperature required to move the glass but slowly.
the problem is getting the flat base causes the upper thinning.

Draping it is far more efficient.
My 20 inch vases had inch thick folds around the lip but they were never thin.

[ejgiebel]

I have taken Amanda's class, you'll learn a lot from her. I've made a lot of these since that class about 15 months ago. I have to agree that was probably too high of a temp, especially with black, since it tends to move fast. I've done quite a few with a similar setup, 3mm of color and 9mm of clear. I can drop them 9 inches and still have color saturation.

The one thing I didn't see in your post is whether the color was on the inside or outside (up or down on the mold). The side against the mold doesn't move as much as the top of the glass, so if your color was down, that could be why. I usually drop them far enough to just get a base started, then use my disk grinder to put a flat base on it, hence I don't want to grind the color away so I put it (generally) on the inside. But I've done it on the outside, and you do get a very different result, but never that little color, although I've never done black. But mine are typically 1mm, maybe 1.5mm after cutting off the rim, and I've never experience what I see in yours.

One other thing that I do, I just take the initial building of the blank to tack fuse temps - 1350, and hold for 10 minutes. Because I cut the rims off, I do a bubble squeeze from 1100 - 1250 at 50 degrees/hour, and I sift clear powder between the layers. This gives me very few bubbles, and what are there are very fine. And I have a 4.5 inch square. Bubbles in these drop rings can be a real pain with long, thin holes filling up with crud from finishing.

Oh, and Amada takes hers to a full fuse, but I like to do precise patterns, and 12mm of glass without damning just moves too much.

[seachange]

Thanks Kevin

I only want to make drop vases at present - only have till the end of august to experiment and play, then the season starts again, so need to concentrate on one thing, with the hope of achieving some decent results.

They are not happening yet (the decent results) but your reply made me take another look at the drop schedule and bring it right down. Followed Paul Tarlow's schedule from his book.

Got better color density, though the walls at the rim are still too thin. So, one tiny step forward.

Will keep at it, hoping I'll be able to afford this. Drop vases take a lot of glass, specially bad ones

Best wishes, seachange

[seachange]

I have taken Amanda's class, you'll learn a lot from her. I've made a lot of these since that class about 15 months ago.

Many thanks for the encouragement, I am looking forward to it. It is a long, long time till then.

I have to agree that was probably too high of a temp, especially with black, since it tends to move fast. I've done quite a few with a similar setup, 3mm of color and 9mm of clear. I can drop them 9 inches and still have color saturation.

I really, really wish I could achive that

Have reduced drop temperature to
182 - 1100 - 0
133 - 1250 - till drop

This is with same black/white blank, 4 layers total, 6" drop. Changed temperature only, to be able to compare. There are so many variables one could try, it is mind boggling.
Color saturation was better. I removed the top to check thickness of the rim, still too thin and fragile, mostly less than 1mm, in some places it is paper thin. Have made 2 more of the same blanks, but at present I feel a bit paralized with indecision, don't know what to change to improve the result

The one thing I didn't see in your post is whether the color was on the inside or outside (up or down on the mold). The side against the mold doesn't move as much as the top of the glass, so if your color was down, that could be why.

Oh. Never knew it could make a difference. This is very interesting - I am learning a lot. Yes, the color was down on the mold. My blanks are, from the shelf up, 3 layer tekta + 1 layer color. Or tekta, white, tekta, black + white strips.

I am fusing the blank with the color strips on the top because I trap bubbles in between the strips if they are covered. Also the white on top of tekta to avoid picking up kiln wash with the opaque color.

Although I have been working with glass for a few years, have never used more than 2 layers of 3mm transparent glass. Trying to get the blank right with 4 layers has also been - still is - a learning curve.

For the drop I am reversing the blank, so the black/white strips are lying on the mold. Imagined the color, being on the outside, would be more intense when one looks at it directly, instead of seeing it through the layers of tekta.

So, if I am working this out correctly, for the black white vase the blank could be, from the shelf up:
tekta
tekta
black+white strips
white

Then for the drop the tekta is on the mold, the inside of the vase will be white, and the black/white strips will be seen from the outside through the 2 layers of tekta. Will this be a better layout? I am personally not that keen on the black/white, but it is a wedding present to be delivered in September...if I can get it right . At present I am going through the glass like if it was water running through my fingers. It will be a very expensive gift.

I usually drop them far enough to just get a base started, then use my disk grinder to put a flat base on it, hence I don't want to grind the color away so I put it (generally) on the inside.

Have been thinking that if I ever get a vase that is worth keeping, I'll do the same. Mainly because the bottom part gets too rounded for my taste (a bit like an onion bulb). Prefer the slimmer shape, more like a cone.

But I've done it on the outside, and you do get a very different result, but never that little color, although I've never done black. But mine are typically 1mm, maybe 1.5mm after cutting off the rim, and I've never experience what I see in yours.

Since I have never seen a finished drop vase, I imagined the rim had to be 2 to 3mm thick. So 1 to 1.5mm is good enough, it does not break when you touch it?

One other thing that I do, I just take the initial building of the blank to tack fuse temps - 1350, and hold for 10 minutes. Because I cut the rims off, I do a bubble squeeze from 1100 - 1250 at 50 degrees/hour, and I sift clear powder between the layers. This gives me very few bubbles, and what are there are very fine. And I have a 4.5 inch square. Bubbles in these drop rings can be a real pain with long, thin holes filling up with crud from finishing.

Oh, and Amada takes hers to a full fuse, but I like to do precise patterns, and 12mm of glass without damning just moves too much.

Aah, one thing at least I worked out almost all right. Tried full fusing. Also found that 12 mm glass spreads out a lot. Have no idea how to keep the thickness without the dams. Plus also got far too many bubbles coming to the surface, even so I had a 1h 15' bubble squeeze at 1225.

Then tried blanks at a high tack fuse, to 1414. Still some spread and some bubbles. So reduced it to 1350 - was more luck than intent, was firepolishing edges on other pieces and decided to try the blanks in the same firing.

Haven't used these blanks yet, but they look better to me. Will improve the next ones with the bubble squeeze, the 10 minutes hold and the sifted clear powder.

Many thanks for all your help and for sharing your insights. I am always prepared to test, but sometimes get to the point, like now, where I can't see what to change for the next test. Have been working on this for the last 6 weeks, doing about 4 drop firings a week.

Tomorrow I will make a new blank and on sunday drop it with the tekta towards the mold. Will report on monday. If you think my drop schedule is still way out, could you please let me know?

I really, really appreciate your help.

All best wishes, seachange (from Down Under)

[jim simmons]

there is a thread on how to make a drop vase with only one firing.
The other jim

[seachange]

there is a thread on how to make a drop vase with only one firing.
The other jim

Thanks Jim. I have printed a post from Tony Serviente from 2004, but has no details on firing schedules. It mentions that he used to do lots of vases at the same time, 4 layers, without prefusing the blanks...which I must say sounds very tempting . Is this the thread you are referring to?

Then there is (or was) a tutorial called "Simultaneous tack fusing and drop ring slumping" in two parts. I only have part two. I am sure I got it from this board, the tutorial must be from Brad?

The tutorial suggests to, quote "start with a rate of 500F/260C and soak for 45 minutes at 1250F/675C. This will help the layers on top to solidly tack fuse. After the soak, heat again (can go AFAP) until 1380F/750C. Now start watching the piece....."

I tried this once in 2012 and once again earlier this year (forgot the test from 2012 and that I didn't like the result then, so just went ahead and ruined another blank ).

Had a 3 layer blank, thought would like a deeper drop, so decided to add another layer. The problem is that in my kiln, when I reach 675C the glass has already started to drop, almost by 1". I can't get the "layers to solidly tack fuse" before they start dropping. If I ramp up slower, I get an even deeper "starting" drop. If I ramp faster, I don't get enough heat accumulated on the blank and the vase walls get very thin - at least this seems to be part of the trouble I am having.

As they layers drop, they separate a tiny bit, trapping (in my tests) a lot of air. The trapped air looks like large pieces of mica flakes - can't think of another better description. It does not look like bubbles at all. It is interesting, but not the look I am after.

Must clarify that boths my tests consisted of a prefused 3 layers blank, to which I added an extra layer of tekta. I am sure that if none of the layers has been prefused, the trapped air would be more evenly distributed and create a more even and pleasing effect. Paul Tarlow explains that in this process the rims tend to fuse together, but this is not the case with vessel's sides, so there is a unique pattern created by the flat spots where the air is trapped. There is a totally beautiful blue/green vase in his book illustrating this technique, among other very nice examples

The technique is very tempting, and I will probably try it one day. This season I have only one modest aim (and only time for this one thing), to achieve some normal, or standard, looking vases.

I will be ecstatic if I can manage this .

Many thanks for your reply, I appreciate it.

Best regards, seachange

[jim simmons]

HI Seachange.
That firing schedule is the one that I gave to Brad.

Simultaneous tack fusing and drop ring slumping
I HAVE A PIC SOMEWHERE OF ONE THAT HAS BEEN FIRED USING THIS SCHEDULE IF YOU ARE INTERESTED.
The other Jim.

Ps sorry about the caps.

[seachange]

Hi Jim

Yes,would love to, if it is not too much trouble to find the picture. Do you remember the vase as being attractive, something you would like to do more off?

Just spent the whole afternoon looking for a firing schedule for a drop vase I had used in my first tests, in 2012.

Still have it, ruined the top trying to smooth the inside of the lip with a hand pad. Got lots of scratches from the pad, so just put the vase aside. But now, 5 years later, realised that the general shape and the thickness of the rim where right, so it was worthwhile to try to find it again. I am fairly sure it was from Laurie (Bonnydoon glass).

That is another technique i still have to learn, getting a smooth inside rim.

Have a very small lap grinder, only 6 ", this is big enough at present to smooth the flat, cut off surface of the lip.

But then there are still the sharp edges on the outside and the inside. I always read about using a hand pad for the inside, this year I'll have to learn to do this. The pads are very stiff, but I still managed to scratch the inside. Never tried again. Now at least I have plenty of reject vases to practice on.

As you can see, getting the vase to drop properly is only half of my troubles

Many thanks, seachange

[jim simmons]

Here you go, (I hope)
I don't know if you can see, but there is absolutely NO cold working involved.
3 layers of glass with strips and frit between 1st and 2nd layers.

The other Jim

https://www.flickr.com/photos/jim_simmons/103889020/

[seachange]

Many thanks Jim

Very colorful and very different, will keep the picture and firing references for the future, definitely something to try. Happy you found the picture

I am making a bit of progress, mainly by changing which coils I am using for the firing, it seems to be working much better. Do not quite yet understand why, but I will give some details in another post a bit later this week.

Will make a few more tests and see if the better results are consistent, not just a bit of luck.

Best wishes, seachange.

[seachange]

Hi again

returning to say thank you to all who helped me with my problems. By jolting me into having a new look at my firing schedules, by showing other options.

And to ejgiebel for such a comprehensive reply, full of good tips. Followed your suggestions for the blank. Included a good bubble squeeze and fine clear frit between the layers (didn't have any powder, have ordered some). The frit worked also, I have now great tack fused blanks with practically no bubbles. The size is perfect for the small BE mold. Great results with a 6"drop, will be testing same blanks for 7 and 8" drops.

Since I am starting to have some success, I am bravely doing more. Fusing 5 new blanks in one kiln, while doing a 7" drop in the other .

Still have to work out the perfect minimum size blank for the next size mold.

With my deeply felt thanks, all best wishes, seachange