[TheForge] preserving heat colors

[Bruce Freeman]

Expanding on this:

Heat colors are the same as oil-on-water colors or of coating-on-lenses
(binoculars, cameras) colors.

In all cases, what's going on is "molecular"-thin layers are refracting
and dispersing the light.  Colors result.

Hence, the oxides are not necessary for the formation of these colors. 
Any transparent material in thin enough layers will do.   That's the
rub.  The index of refraction of the transparent material probably
matters somewhat, but maybe not all that much. 

If you coat the oxide layers with a lacquer that has an index of
refraction greatly different from air (which is probably a given,
considering the density difference), then you run the risk of destroying
the color effect.  If you can get a lacquer that ALSO differs in index
of refraction from the oxide layers, then maybe you won't destroy the
colors.

In my limited experience, density and some aspects of the chemistry
(polarizability, I think) are related to index of refraction.  (This is
off the top of my head - I have not recently researched this.)  Hence,
it seems likely that a highly halogenated "lacquer" might possibly have
a high index of refraction and might therefore preserve oxide colors. 
(Totally speculation at this point.)

Somebody with more experience with optics might comment...

Perhaps a better alternative might be to come up with a way of
depositing a "molecular" thin layer of a highly effective lacquer (maybe
containing BHT or some other such antioxidant).  Good luck.

Niobium jewelry often bears these colors.  I wonder whether steel could
be niobium plated?...

Bruce
NJ


>>> Hochewa at aol.com 3/14/2005 8:26:01 AM >>>
To All,
Heat colors are not the color of the oxide that has formed.  The oxide

actually is transparent and the colors you see are the refraction of
light just like 
a prism.  The oxides in thickness are multiples of the wavelength of
the 
color you see.  When you add a protective layer you add to the
thickness of the 
refracting layer and you change the color.
I ahve done several pieces that also have gone much more blue than I
wanted 
but they also retain other colors.  It appears that if you thin the
oxide layer 
you put on at first and then add a layer of acryllic you may end you
where 
you want to be.  If the pieces are for indoor use maybe a thin layer of
really 
good wax may be enough.
I like the effect ot the temper colors.  
Keep playing with them.  You may find something we all can use.

Regards,

Hochewa

In a message dated 3/13/2005 1:06:27 PM Eastern Standard Time, 
gladish at cnw.com writes:
Woolley wrote:

Greetings,

When I discovered how beautiful an effect I could get with an
acetylene
torch on polished (it must be polished, bright, as in no mill scale,
not
just wire brushed) mild steel ( purples,greens blues) I thought I was
going
to be able to use this finish for all kinds of decorative stuff (
panels,
furniture) until I tried to fix it.  I found that if I sprayed a
lacquer or
any kind of clear it would go like an ice blue color time and again. I
have
managed to preserve the oxide colors with oils but these never dry so
the
pieces can't  really be handled too well (not a good selling point for
furniture).  I have pretty much abandoned this finish. My two cents.

Regareds,
Bill Woolley
_______________________________________________
Manage membership or unsubscribe at:
http://mailman.qth.net/mailman/listinfo/theforge 
theforge mail list group photo site is
http://www.photoaccess.com 
Login:  blacksmithblacksmith at hotmail.com 
password:  anvil
___________