Warren Thom wrote:
>
>I have looked around the web for more information and found a caution of:
>
>"Because of its porosity you do not get a satisfactory anodized finish on
>cast aluminium which has been machined. An as-cast aluminium surface will
>not have a lusterous finish when anodized. (looks poor)"
>
>What might one do if they wanted to anodize the Schmoyer dial? It is
>aluminum cast, isn't it? Will it work on a cast surface that has been
>smoothed? What does it mean to be "machined"? I would think "machined"
>means to grind and mill the surface smooth. Have you found surfaces of
>aluminum (or is that aluminium - Al u MIN nee um) that have not worked
>well?
In my limited experience of anodising aluminium castings, if you want clear,
even 'bronze look-alike' I would have to agree. The few castings I anodised
were always blotchy, even on dressed surfaces. I have no evidence to support
my theory but I always thought it might be due to uneven dispersion of copper
in the skin of the casting or just its irregular structure due to skin
chilling. A partly dressed LM6 sandcasting dyed black took on an interesting
silvery grey 'forged iron' look which we often used to good effect but other
than that I would always select drawn or rolled material for anodising.
>I have found your steps very interesting. I have always wanted to find a good
>link of sun >dialing to chemistry.
That is how it started for me. I was tasked with finding interdisciplinary
projects which would involve contributions from the teachers of chemistry,
physics, art and workshop crafts.
What could be better than anodising? Many sessions, many kids, much anodising
and not a single incident.
Best Wishes
Tony
======================================================================
\ ** ******
\\ ** **
\\ ** *******
*\\ ** **
*\\ ******* *******
**\\
***\\ Tony Moss, Lindisfarne Sundials
*****\\ 43, Windsor Gardens, Bedlington,
*******\\ Northumberland, England, NE22 5SY,
**********\\ 55° 07' 45" N 1° 35' 38" W
Tel/FAX +1670 823232
Mobile: 07970 208 540
Website: http://www.lindisun.demon.co.uk
======================================================================
The first choice for a Millennium Sundial.
(every one Y2K compliant)
Horizontal, Vertical, Declining, Analemmatic, Equatorial,
Polar and Capuchin Sundials individually made in solid
engraving brass. Professional-quality Dialling Scales,
'engine-divided' meridian layout instruments with software.
Analemmatic dial plots - any size for any latitude.
Graduation, re-cutting and restoration of scales.
'Lintique' patination of brass.
=======================================================================
