That may have been true in the old days, but isn't that case any longer.

Sputtered coatings are just too difficult to handle in the window-manufacturing process because
there is no true bond between the coating and the glass, so the coating can be scratched or rubbed
off too easily. Basically, an electron beam is aimed at a disc of the material to be applied to the
glass. As the atoms and molecules are sufficiently energized, the "sputter" off of the surface
(vaporize) of the source, and deposit like soot on the surface of the room temperature glass.

Essentially all of the Low-E glass made now is the pyrolytically-deposited "hard coat." As it is
applied when the glass is still quite hot, early in the forming process, the organic chemical
precursors react with the glass to form a chemically bound (Si - O - Sn), ceramic oxide coating that
is almost impossible to remove (we've had to do it in the lab, and it's a pain...).

The so-called "oil slick appearance" was due to varying thickness in the coating, leading to the
formation of interference colors - again, no longer a problem due to advances in the coating
application equipment.

The application surface is selected by what the climate you will be placing the window in. For the
most part, they are used in places where you are trying to trap heat in the home. Basically, the
coatings are transparent to short wavelength infrared (the rays that heat you and objects up), but
reflect long-wave IR, the heat generated. So, sunshine comes in, warms the floor and furniture, and
as the heat attempts to be reradiated out through the window, the interpane gap, often filled with
argon (a poor thermal conductor), stops some of the rays and the oxide layer on the second surface
(as counting from the outside) does the rest.

If the climate is very warm, the coating is on the third surface so that the
low-thermally-conductive gap is before the film, reducing the heat entering the home. That is not a
common application, as the savings don't seem to warrant the added cost. Folks with second-surface
coatings do get some benefit in the heat of the summer, but less so, as there is no gap before the
coating...

Incidentally, every glass container you've had your hands on in the last 35 - 40 years also has a
(much thinner) tin oxide coating on it (that's where we started the low-e development idea), but for
protection of the glass during forming and subsequent handling, not anything energy related.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!

.. . . . . . . . . . .
"TRAINMAN9" wrote in message
...
Actually, the amount and specific wavelengths of light blocked by Low-E
coatings depends on the
chemistry of the coating, it's thickness, and to a lesser degree, which
surface it coated.

Most of the modern spudder coat Low E is on the number two surface and is made
up of two layers of silver with several layers of oxides to make it possible to
see through the glass.

Hard coat Low E glass used tin based coatings that were fused when the float
glass was made. These coatings are typically on the number three surface. They
do not perform as well as the spudder coated products, have an oil slick
appearance and in most cases do not meet the new Energy Star requirements for
shading co-efficient or solar heat gain. They typically only block about 55% of
the UV.

That may have been true in the old days, but isn't that case any longer.

Sputtered coatings are just too difficult to handle in the
window-manufacturing process because
there is no true bond betwe

Ray you are so wrong about this. The majority of windows produced today for the
residential market use spudder coated low emissivity coatings. The largest and
most recognizable name in the window industry Andersen has been using Low e
squared for at least ten years. All of their insulated units for their window
and door products are provided by Cardinal Corporation one of the leading
suppliers of spudder coated products in the US. The also make all the glass for
Marvin and other wood window manufacturers as well as the leading vinyl window
manufactures in the US and Canada.

The coating are on the second surface and are designed to meet the new four
zone energy Energy Star requirements. Hard coat low e cannot meet the strict
thermal, solar heat gain and shading co-efficient requirement of the IBC which
has been adopted in a majority of the states in this country. In fact
Pennsylvania just passed it last year and have begun enforcing the NFRC
labeling requirements.

As for adhesion between the spacer and the glass all spudder coated glass is
edge deleted where the coating is removed allowing excellent adhesion of the
warm edge spacer systems.

Hey, you might be right, but please get the word right: it's "sputter," not "spudder."

I haven't been in the glass coating business - supplier or buyer - for a few years, so my info
appears to be outdated...

No argument that sputtered coatings have better electrical properties - that is how they work - but
the simple fact is that they are not durable in the manufacturing process.

I looked at the Cardinal Glass info, and it's pretty interesting!. Thanks for pointing it out.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!

.. . . . . . . . . . .
"TRAINMAN9" wrote in message
...
That may have been true in the old days, but isn't that case any longer.

Sputtered coatings are just too difficult to handle in the
window-manufacturing process because
there is no true bond betwe

Ray you are so wrong about this. The majority of windows produced today for the
residential market use spudder coated low emissivity coatings. The largest and
most recognizable name in the window industry Andersen has been using Low e
squared for at least ten years. All of their insulated units for their window
and door products are provided by Cardinal Corporation one of the leading
suppliers of spudder coated products in the US. The also make all the glass for
Marvin and other wood window manufacturers as well as the leading vinyl window
manufactures in the US and Canada.

The coating are on the second surface and are designed to meet the new four
zone energy Energy Star requirements. Hard coat low e cannot meet the strict
thermal, solar heat gain and shading co-efficient requirement of the IBC which
has been adopted in a majority of the states in this country. In fact
Pennsylvania just passed it last year and have begun enforcing the NFRC
labeling requirements.

As for adhesion between the spacer and the glass all spudder coated glass is
edge deleted where the coating is removed allowing excellent adhesion of the
warm edge spacer systems.