Supplied in a plastic gripseal bag.
This shelf primer is used for
coating kiln shelves and moulds before firing to prevent the glass
sticking to the surface. Hot glass will stick to most ceramic or metal
surfaces and crack as it cools, unless prevented by a separator such as
Each batch is kiln tested to ensure consistency from run to run.
part shelf primer powder to 5 parts (by volume) water. Stir the mix
frequently during application. Each bag will coat approximately thirty
20" x 20" shelves when mixed 1 part primer with 5 parts water, with the
required 5 coats per shelf.
five coats of primer on a new shelf or mould and also on subsequent
applications. Apply the shelf primer with a wide, natural bristle
brush, a Haik brush is ideal for this. Brush in one direction, then at
a 90 degree angle, and then diagonally, applying as uniformly as
possible. After applying five coats, dry the shelf or mould in your
kiln at 260 degree C for 20 minutes. Take at least 30 minutes to bring
ceramic moulds up to temperature, Mullite shelves can be fired up to
temperature as fast as your kiln permits. Allow shelves and moulds to
cool before use.
For steel, steep sided or non-porous moulds, the
liquid shelf primer can be sprayed onto the mould. Heat the mould to
204 degree C in the kiln, then remove and spray the warm mould surface
with primer until it no longer dries quickly. Reheat the mould and
re-spray. Repeat this process until the mould surface is thoroughly
covered with primer. Metal moulds with steep sides may require up to 10
on the temperature at which you fire a shelf or mould, you may or may
not need to clean and re-prepare it before your next firing. If you are
not firing over 704 degrees C then you can reuse shelves and slumping
moulds many times without reapplying primer, providing the primer has
not been scratched through.
If firing above 704 degrees C then the
shelves and moulds will need to be cleaned and recoated before each
use. Scrape off the old primer with a wide tile scraper - scraping
rather than sanding reduces dust. To remove primer from a shaped
surface use a scouring pad.
you don't kiln dry your shelves you cannot be completely confident that
they are thoroughly dry. Surfaces that feel dry to the touch may still
hold moisture that can cause bubbles, glass sticking and breakages.
Shelf primer is drying to the skin so wear thin rubber gloves to prevent chapping.
breathing shelf primer dust. Wear a respirator approved by NIOSH for
dusts, and/or clean your shelves outdoors or with a good local
the primer powder in a tightly closed container and store in a cool,
dry place. Mixed, unused shelf primer will last for many weeks if kept