Fusing and painting float glass

Fusing and painting float glass

Post by Gerry Everso » Mon, 27 May 1996 04:00:00



  Earlier this week Bob Guenter and Jeanne Kent were wondering why
float glass was behaving badly when fused or melted in a kiln.
 Float glass has two different quality faces. Apparently this is a
result of the manufacturing process -one side is the "tin" side and
the other the "up" side.
  If you cut a piece of float glass, flip one section over, and paint
on a silver nitrate stain, and fire both at the same time, you'll find
the stain quality quite different after firing.
  The bothersome solution is keeping track of the "best" side during
your working process.
  Also----if you're fusing, the annealling temperature ranges change
after the first firing. This holds for regular window glass as well.
  Maybe there's a web site at Corning Glass that will have more
details. Anyone know?
            Gerry

 
 
 

Fusing and painting float glass

Post by The Sandpee » Mon, 27 May 1996 04:00:00


Quote:

>   Earlier this week Bob Guenter and Jeanne Kent were wondering why
> float glass was behaving badly when fused or melted in a kiln.
>  Float glass has two different quality faces. Apparently this is a
> result of the manufacturing process -one side is the "tin" side and
> the other the "up" side.
>   If you cut a piece of float glass, flip one section over, and paint
> on a silver nitrate stain, and fire both at the same time, you'll find
> the stain quality quite different after firing.
>   The bothersome solution is keeping track of the "best" side during
> your working process.
>   Also----if you're fusing, the annealling temperature ranges change
> after the first firing. This holds for regular window glass as well.
>   Maybe there's a web site at Corning Glass that will have more
> details. Anyone know?
>             Gerry

You are correct about the "good" and "bad" acting sides caused by the
molten tin that float glass is "floated" on during manufacturing.  Dan
Fenton showed me a trick of using a UV light to tell the tin from the up
side Prior to fusing/painting.  He sold a UV tester that was nothing
more that a 6v lantern with a UV bulb, although ANY UV bulb/lamp would
do, (so check out your closet under the "60's blacklight "section.)  FOr
the life of me, can't remember what the UP side looked like under the UV
- only remember there was a difference - anybody?
  Sandpeep

 
 
 

Fusing and painting float glass

Post by j quinn fitzpatri » Fri, 31 May 1996 04:00:00



Quote:

>   Earlier this week Bob Guenter and Jeanne Kent were wondering why
> float glass was behaving badly when fused or melted in a kiln.
>  Float glass has two different quality faces. Apparently this is a
> result of the manufacturing process -one side is the "tin" side and
> the other the "up" side.
>   If you cut a piece of float glass, flip one section over, and paint
> on a silver nitrate stain, and fire both at the same time, you'll find
> the stain quality quite different after firing.
...Snip snip
>             Gerry

Hello all
   There is a way of finding out which side is the Tinned side. A small
blacklight, sold at lapidary stores, used to view flourescent minerals. If
you shine it on both sides of the glass in a dimly lit room, you can see a
metallic looking film on the tinned side.
   It's not only important in fired painting, but in fusing and gold leaf
work too. it's best to always work the "clean side of the glass.

Till then quinn

--
***************************************************************
*  J Quinn Fitzpatrick             *  "I am not young enough  *

*  http://www.instanet.com/~quinn  *                          *
***************************************************************

 
 
 

Fusing and painting float glass

Post by Steve Herric » Fri, 07 Jun 1996 04:00:00


In a class at Cal Poly SLO we were taught about clear float glass having a
tin side and a clear side. As long as the sides were the same for the
whole piece it was ok, but if you put the non tin side and the tin side up
then you would notice a difference. To tell the difference in the sides, a
black light source was used in a dark room. The tin side show up
differently than the non-tin side. This might work for colored glass as
well.


           Steve Herrick

Quote:

>   Earlier this week Bob Guenter and Jeanne Kent were wondering why
> float glass was behaving badly when fused or melted in a kiln.
>  Float glass has two different quality faces. Apparently this is a
> result of the manufacturing process -one side is the "tin" side and
> the other the "up" side.
>   If you cut a piece of float glass, flip one section over, and paint
> on a silver nitrate stain, and fire both at the same time, you'll find
> the stain quality quite different after firing.
>   The bothersome solution is keeping track of the "best" side during
> your working process.
>   Also----if you're fusing, the annealling temperature ranges change
> after the first firing. This holds for regular window glass as well.
>   Maybe there's a web site at Corning Glass that will have more
> details. Anyone know?
>             Gerry

 
 
 

Fusing and painting float glass

Post by Richard Schwart » Sun, 16 Jun 1996 04:00:00


I am a builder of light weight telescope mirror blanks.  I have been
using salvaged store front windows, which are mostly float glass.  

My mirrors consist of a front and rear disk with a layer of ribs between,
like an airplane wing (I was in the aerospace industry too long and
became brain infected).  So when I do my thermal diffusion bonding, it is
the EDGE of a piece of glass against the FACE of another piece.  No
problem.

I have determined that if you multiply the Young's modulus of glass by
the coefficient of thermal exansion, and allow for a thermal drop of
about 400 degrees C (after annealing, of course), you must have the
thermal expansion of two pieces match within a few percent to avoid
approaching the 1000 psi fracture point of typical glass.   I accomplish
this on my unknown salvage glass by taking all parts of an assembly from
a single sheet.  I don't know what the physical characteristics are, but
they are going to be the SAME.

If you are interested in this and other topics related to glass working,
check out the ATM archives and subscribe to the ATM mailing list.

There is much to learn.