fusing with lava cloth problems help please!!!!!!!!!!!!

rhonday · Post by **rhonday** » Mon Apr 12, 2004 8:04 pm

I purchased lava cloth I pre-fired it and set 3 layer high glass tiles on to fuse at 1400 full fuse my glass tiles kind of sunk slightly to middle and did not fuse fully leaving slightly raised bumps I also did a 30 minute soak. kiln scheldule was
300 per hour to 1400 30 min soak off I normally fuse regular 3 layer tiles for cabachons like this only difference being I have fused on kiln shelves.

why did my tiles sink inward slightly and leave raised bumps.
help needed soon I have a home show this weekend I don`t understand why they came out this way. I used the lava cloth for the texture on the back to give the tiles better grip for grouting.

Rhonda

Brock · Post by **Brock** » Mon Apr 12, 2004 8:06 pm

rhonday wrote:I purchased lava cloth I pre-fired it and set 3 layer high glass tiles on to fuse at 1400 full fuse my glass tiles kind of sunk slightly to middle and did not fuse fully leaving slightly raised bumps I also did a 30 minute soak. kiln scheldule was
300 per hour to 1400 30 min soak off I normally fuse regular 3 layer tiles for cabachons like this only difference being I have fused on kiln shelves.

why did my tiles sink inward slightly and leave raised bumps.
help needed soon I have a home show this weekend I don`t understand why they came out this way. I used the lava cloth for the texture on the back to give the tiles better grip for grouting.

Rhonda

Not fully fused. Not hot enough, long enough. Brock

rhonday · Post by **rhonday** » Mon Apr 12, 2004 8:20 pm

Thank You
Brock but are you saying I should go to 1450 or 1500 ( what is overfire)
I also did put kiln poata on corners to keep cloth from curling. and How long should I soak for this even heat kiln floor model I had the whole floor covered with about 20 4x4 tiles.

Rhonda

Brock · Post by **Brock** » Mon Apr 12, 2004 8:28 pm

rhonday wrote:Thank You
Brock but are you saying I should go to 1450 or 1500 ( what is overfire)

You have to go hot enough, or long enough to achieve what you want. The number is variable, but certainly a minimum of 1450 is normal. For some glass! What glass are you using?
Overfire is when you exceed the temp for a process. A blob

I also did put kiln poata on corners to keep cloth from curling. and How long should I soak for this even heat kiln floor model I had the whole floor covered with about 20 4x4 tile?

Don't know, again, kilns are different. I could give you a suggested schedule, with more information, as could lots of people here. Brock

Rhonda

rhonday · Post by **rhonday** » Mon Apr 12, 2004 8:39 pm

I would be so thankful if you could give me a couple of suggested scheldules
And i thank you ever so much
roni@metrocast.net

Rhonda

Tony Smith · Post by **Tony Smith** » Mon Apr 12, 2004 8:41 pm

Did you weight down the outside edges of the lavacloth? There is a differential COE between the lavacloth and the glass. As the glass starts flowing, it sinks into the weave of the cloth and really has a good grip on it. When the glass and cloth cool, the glass shrinks more than the cloth and the cloth causes the glass to "potato chip". Since this happens at a temperature that's still pretty fluid for the glass, it can cause the glass to pool toward the middle.

I use mullite dams along the outside of the lavacloth whenever I'm firing on it to hold it down and that seems to solve the problem. The other solution is to sprinkle some dry kilnwash on the cloth and it fills in the weave and keeps the glass from sinking in so deep. That cuts down the texture somewhat and lets the glass slip a bit on the surface.

I wouldn't recommend experimenting with a new process on something that's important. That's a guarantee that Murphy will find some way to screw you up.

Tony

rhonday · Post by **rhonday** » Mon Apr 12, 2004 8:47 pm

Thank you Tony I did weigh down around all the edges lava cloth with kiln posts and lava cloth is one big sheet . And your right about experimenting I just got the long lecture (deserved) I quess from my husband.

Rhonda

Tony Smith · Post by **Tony Smith** » Mon Apr 12, 2004 8:57 pm

If I read your post correctly, you have multiple small tiles on one big sheet of lavacloth. This is porbably contributing to the problem since the lavacloth isn't weighted down between the tiles.

Try a teaspoon of dry kilnwash and spread it around with a squeegee or ruler... try to spread it evenly so that it gets into the weave of the cloth. You'll still have a texture, but without the other associated problems.

Good luck. (sorry about the lecture)

Tony

Brock · Post by **Brock** » Mon Apr 12, 2004 9:04 pm

rhonday wrote:I would be so thankful if you could give me a couple of suggested scheldules
And i thank you ever so much
roni@metrocast.net

Rhonda

Size and glass would help, but for Bullseye, Spectrum. or Uroboros, try:

300 dph 1150
Hold 30
100 dph 1450
Hold 30
300 dph 960
Hold 60
100 dph 760
Hold 60
Off

This is incredibly conservative for tiles.

The hold at 1450 should be checked to determine what is required in your kiln.

Brad Walker · Post by **Brad Walker** » Mon Apr 12, 2004 9:06 pm

I made my magnets (which were roughly 1 1/2" square) on lava cloth. I fired to 1450 and held for 10 minutes. I fired most of the magnets in one firing, placed on the cloth and with only the edges of the cloth anchored down. It worked no problems. I used both Bullseye and Spectrum glass (though not in the same magnet, of course).

The bigger question to me is why you're using the lava cloth if all you want is to have a little texture on the back of the tile you're firing. To get a little texture, just fire on fiber paper or sprinkle something on the shelf. Dry plaster, whiting, or kiln wash powder would all work -- Barbara Cashman, who makes glass tiles for a living, mostly uses sifted plaster on her kiln shelves to give it just a little texture. Lava Cloth is definitely overkill if that's all you want to do.

Brock · Post by **Brock** » Mon Apr 12, 2004 9:09 pm

The bigger question to me is why you're using the lava cloth if all you want is to have a little texture on the back of the tile you're firing. To get a little texture, just fire on fiber paper or sprinkle something on the shelf. Dry plaster, whiting, or kiln wash powder would all work -- Barbara Cashman, who makes glass tiles for a living, mostly uses sifted plaster on her kiln shelves to give it just a little texture. Lava Cloth is definitely overkill if that's all you want to do.

What IS it good for? Seriously. Brock

rhonday · Post by **rhonday** » Mon Apr 12, 2004 9:09 pm

Thank You Brock and Tony for your help I so do appreciate it. Glass is all bullseye with 90 coe dichroic and some pixie dust and some tiles have honova gold embellishments and all is a thin base with designed dichroic in middle and a clear top coat

KellyG · Post by **KellyG** » Mon Apr 12, 2004 9:12 pm

Rhonda, If I read this correctly, all you want to achieve is a good texture for better tile adhesive, right. Probably already thought of this, but can you just sandblast the back to rough it up?

I haven't used lava cloth yet, so the help here is good info for the future.

...Kelly

rhonday · Post by **rhonday** » Mon Apr 12, 2004 9:13 pm

I also used lava cloth because centre deverre employee stated tile workers like the texture on tiles better. I guess I really should have experimeted more first no harm done though I `ll refire them all tomorrow.

Rhonda

Tony Smith · Post by **Tony Smith** » Mon Apr 12, 2004 9:16 pm

Brock wrote:What IS it good for? Seriously. Brock

When used properly (after some practice), it adds a nice, uniform, fabric-like texture to the glass.

Tony

jennifer webb · Post by **jennifer webb** » Mon Apr 12, 2004 11:27 pm

about lava cloth----brad, you mentioned lastyear in your reply to rhonda that you did all your magnets on one sheet of lava cloth in one firing....were they more than one layer? were they solid pieces or did they have bits of other elements? did you use irid glass for the side down?
and since its been a year from those posts what have you done with the lava cloth since?

Brad Walker · Post by **Brad Walker** » Mon Apr 12, 2004 11:41 pm

jennifer webb wrote:about lava cloth----brad, you mentioned lastyear in your reply to rhonda that you did all your magnets on one sheet of lava cloth in one firing....were they more than one layer? were they solid pieces or did they have bits of other elements? did you use irid glass for the side down?
and since its been a year from those posts what have you done with the lava cloth since?

Last year??? I made the magnets this past February. I used scraps of glass that were cut from other projects. No irid, two to three layers thick.

I like the texture of the lava cloth. (So much so that I often flip the piece after firing and refire with the texture up -- that's what I did in the magnets. Even with a second full fuse to 1500F, the texture does not go away.)

Michael McNerney · Post by **Michael McNerney** » Tue Apr 13, 2004 7:59 am

Rhonda,
Check out my pics on the picture page. "Fused Panels"
I fired these on thin Fire and have little or no texture at all on the backs and had no problem hanging them.

Michael

WarmGlass.com