Well, I tried twice more and still no sucess. Perhaps someone has
The wax: around 1 x 3/4 inches, thin in the center (perhaps 1.3 mm)
and thicker around the edges, aruond 3 mm. There is some moderately
fine detail in the wax. Note that i am using Argentium casting
grain, from Rio. It this case it is around half new grain and half
leftover silver from the last attemp(s).
Attempt 1: sprue around 4 mm wide at the narrowest, where it meets
the model. I sprued it at the edge of the model, where it is
thickest. 4 air vents on opposite side. I used around 1.3 times the
calculated silver weight, to allow for the silver in the plug and
air vents. Heated it using propane and oxygen, and a melting
tourch-tip, using a bit of borax added right before pouring. The
result was around 1/3 of the model filled.
Attempt 2: basically the same sprue and vent arrangement. I added
more silver this time, over 2 x the weight of the actual model. It
took around 7 minutes to melt the silver this time. I heated it up
more than the first attempt. It was definately liquid, not really
glowing, though the crucible under it was a bit. I swirled it around
and continued to heat for around a minute after it was liquid. This
time I saw silver in the air vents and thought it had worked. What
actually happened was it filled the outer thicker part, but not into
the center (thinner) part of the model.
I also noticed (and have noticed on other attempts) that the part of
the model that does fill doesn’t have the full detail of the model.
It looks like it has been sanded down. So, I wonder if the metal is
hot enough. How does one know? i dont want to overheat either.
Is the Delft system only good for larger items like rings? I am
interested in pendants right now, and they cant be too thick, or
else they are too heavy. Perhaps it wont work on thinner items. I do
have a miling maching, so perhaps i could cast it thicker and plane
down the back after using the milling machine.
Any more suggestions?
Living Color Opal and Intarsia