Silhouette Plaques created with a paper cutout. Thick paper was first saturated by melting
household wax, a fire hazard if the temperature is not kept to the minimum.
|
JQ's Fat White
|
| gerstley borate |
300
|
| custer feldspar |
180
|
| ferro frit 3134 |
72
|
| epk kaolin |
12
|
| tin oxide |
30
|
| zircopax |
6
|
Plaque was sprayed with a porcelain slip
while green, to produce the ultra-pure white. Mill
the zircopax if necessary. Sieve at 80 minimum.
|
MCC's
White Crackle
|
| gerstley
borate |
80
|
| nepheline
syenite |
20
|
| tin
oxide |
2 - 8 %
|
|
|
JQ's Cobalt Flash
|
| gerstley borate |
320
|
| silica |
60
|
| feldspar |
20
|
| cobalt carbonate |
25
|
| whiting |
12
|
| bone ash |
8
|
| copper carbonate |
8
|
|
Reduce the cobalt quantity to produce
a copper mirror glaze.
|
 I
applied the glaze thick on top of the plate, thin on the underside
(left image). This formula will show some crackle where
thin. Click on the image to the left to see the crackle
detail.
|
Both these pieces were spray glazed over the
waxed art paper cut outs.
|
|
|
|
Raku vase by Louden Kiracofe.
I found this exciting red crackle at an art show in Durango,
CO. I searched out the artist, Louden Kiracofe, and obtained
the formula. Louden agreed to share it with others.
|
| gerstley borate |
80 |
| cornwall stone |
20 |
| Mason stain # 6033 - "Sunset" |
20 to 25 |
Detail of Louden's Red crackle.
|
|
|
| gerstley borate |
130
|
| nepheline syenite |
32
|
| silica |
30
|
| copper carbonate |
30
|
| red iron oxide |
10
|
| cobalt carbonate |
5
|
This formula has sufficient silica for the copper
flash colors to persist. I placed a piece in direct sunlight for
one year to ensure the stability of the copper flashing.
|
|
|
| gerstley borate |
800 |
| bone ash |
200 |
| copper carbonate |
50 |
| cobalt carbonate |
25 |
| tin oxide |
12 |
This formula will copper flash, however, after a few years the
copper flashing colors will dissappear, leaving the blue colors.
I also tested this formula in direct sunlight. The color changed
rather quickly.
|
|
|
This recipe may benefit from a little more experimentation,
especially with slight adjustments in the quantities of
the metals. The result is a burgundy red in reduction,
opaque and smooth where thick and with copper flashing.
With oxidation the result can be a green crackle that
is very sensitive to cooling rate. The lampbase at the
right illustrates the range of results. The green area
may have fired hotter, or an area of oxidation in the
firing process resulting in the two distinct color areas on one
piece.
|
|
gerstley borate
|
400
|
|
nepheline syenite
|
100
|
|
bone ash
|
40
|
|
silica / flint
|
40
|
|
red iron oxide
|
25
|
|
copper carbonate
|
20
|
|
zircopax
|
15
|
|
lithium carbonate
|
10
|
|
cobalt carbonate
|
6
|
|
|
|
Zowie
|
| gerstley
borate |
80
|
| nepheline
syenite |
20
|
| lithium
carbonate |
10
|
| copper
carbonate |
5
|
| red
iron oxide |
1
|
|
|
Patina
|
| gerstley
borate |
80
|
| bone
ash |
20
|
| copper
carbonate |
10
|
| tin
oxide |
1.25
|
| cobalt
carbonate |
0.25
|
| For
Blue Patina decrease copper carbonate to 2. |
|
