Mayco Raku glazes are designed to develop beautiful
metallic lusters and crackle patterns when fired according to raku
firing processes. There are several methods and many nuances to raku
firing - for our purposes here we define raku firing broadly as the
processes of firing an earthenware body and glaze in a kiln, removing
the ware from the kiln after it has reached proper temperature, placing
it in a container of combustible material and enclosing the container to
reduce the oxygen in the container.
Product Features and
Some qualities of Mayco Raku glazes include:
Shake for 5-6 seconds before use. Stir well. Apply 2
coats to cone 04 bisque (1940°F, 1060°C). Do not glaze bottom of ware.
Allow to dry thoroughly. Fire to cone 06 (1850°F, 1010°C) and hold for 5
minutes. Reduce in your choice of combustible materials.
Because each of Mayco's Stoneware glazes
has its own unique attributes and characteristics, please see the
following link to learn more about specific stoneware glazes courtesy of
Q: Your label states that Raku glazes are "Food Safe",
yet you also include the statement "May not be suitable for food
surfaces due to surface characteristics"?
Safety is determined by standards established by the Food and Drug
Administration (FDA). ASTM method C-738 and C-927-80 are "leach tests";
the tests involve measuring the chemical composition of an acidic food
before exposure to a glazed surface and the chemical composition after a
several days. If the levels of glaze materials found in the food are
below the established limits, the glaze can be marketed as "Food Safe."
Glazes that create dimensional surfaces also create
crevices and nooks that can trap food - even after washing. This food
can develop bacterial growth and cause health issues. Our policy is to
discourage the use of textural glazes on ware that is intended for food
usage even though the glaze has met all food safety criteria.
"Mayco Raku Glazes will display a
variety of iridescent, metallic and/or crackled fired surfaces.
(Chip sample on label was fired to temperature, at the maximum ramp
rate, and immediately reduced in a lidded container densely packed
with a mixture of newspaper and straw).
Stir well. Apply 2 coats to cone 04 bisque (1940°F, 1060°C). Do
not glaze bottom of ware. Allow to dry thoroughly. Fire to cone
06 (1850°F, 1010°C) and hold for 5 minutes. Reduce in your
choice of combustible materials.
coats tend to produce greater metallic effects. If you are not
getting the desired metallic results you can adjust your glaze
Use of a thermal shock-resistant
raku clay body will help reduce the incidence of cracking.
Actual fired results will vary
according to choice of clay body, glaze application thickness,
glaze fire temperature, combustible materials, reduction
process, kiln, etc.
If using an electric kiln make
sure power is off before removing ware with metal tongs.
Minimizing the distance between
the kiln and the reduction container can improve the development
of metallic colors.
After ware has completely cooled
use water and a scouring pad to clean; cleaning will improve the
luster and colors in the fired finish.
Updated product usage tips,
interesting glaze combinations can be found on our website:
Proper safety processes and
personal protective equipment are very important when doing Raku as
you are exposed to high heat, flames and smoke. Always wear fire
protective clothing, fireproof gloves and protective eyewear. Do not
open or insert tongs into an electric kiln without shutting off.
Reduction process should take place outside of building due to
flames and smoke. Do not spray apply glazes without a NIOSH approved
respirator and other personal protective equipment.
Non Toxic and Non Hazardous when used according to
manufacturer’s directions. Not Recommended for Food Surfaces."