White Midfire
White
Mid Fire Technical data
Frequently asked questions about White Midfire
Why should I use this body?
It is designed to produce strong, tough ceramic pieces.
Ideally suited to functional ware. It will not chip or break as easily as
earthenware & the glazes are tougher & more scratch resistant.
Is it as strong as Stoneware or Porcelain?
Yes - if correctly fired to 1200 - 1220°C (Cone 5 - 6)
What glazes suit this body?
We recommend our 3 base glazes
|
WVG250 |
Clear Gloss |
|
WVG251 |
White Gloss |
|
WVG252 |
Translucent Satin |
Will other glazes suit this body?
No - only guaranteed glazes are listed above.
Can I stilt my pieces – like earthenware?
No – as this body becomes vitreous it would soften and slump
over the stilts.
How then do I glaze fire my pieces?
All pieces must be dry footed (unglazed on foot) – unlike
earthenware – and as the body is vitreous it will not absorb water and hence
is safe on timber surfaces – as long as pieces are fired correctly.
Will my kiln fire to this temperature?
Most kilns will quite successfully – check with your
manufacturer or supplier.
Is it as easy to use as earthenware?
No. Because of the vitrification range of this body you must
be aware of hot and cold spots in your kiln. Test fire with witness cones set
throughout your kiln first. Hot spots may cause slumping & cold spot
immaturity.
Will the ware made from this body be considered ovenproof
& dishwasher & microwave safe?
Yes - if fired correctly to vitrification the body will
exhibit the sufficient strength & resilience.
How will I recognise the slip? Does it appear different
from my current slip?
It is white in colour & will not appear any different to
any other of our white slips. If White Midfire is going to be used as a second
slip you will need to change some of your work practices. Firstly, we would
recommend adding an organic dye to one of the slips in order to be able to
recognise the different greenware and scrap. Care must be taken in choosing this
dye to ensure it burns out completely at the required temperature & doesn’t
effect the fluidity of the slip. Test on small amount first. As the organic dye
burns out in the biscuit firing we also recommend marking the greenware with a
stamp or scratch so it is discernable from others after firing. If White Midfire
is fired at earthenware with earthenware glazes the result will be crazing
of the glazes. If it is fired at stoneware the clay may slump.
How should I fire lidded casseroles, etc?
This depends on the design & the care taken in forming.
Test both separately and together. Perhaps try a wax emulsion with calcined alumina
in it, applied to the gallery and lips of the lids & firing carefully
together. Avoid over firing as they will stick.
How will colour develop at this temperature?
All of the Walker Opaque Underglazes & Design Colours are
designed for this temperature range & should develop the same strength &
brilliance with correctly applied glaze & correct firing.
Are all shapes suitable for the body?
As the body softens at temperature & then vitrifies there
are some shapes that are satisfactory at earthenware that are not at 1200 - 1220
°C. Large overhang i.e. lips of plates over small feet or fig wires may slump.
There may be some slumping centrally if the foot ring on plates is too large. It
is suggested to test fire each shape to check is suitability.
Is it easy to mix a casting slip?
With most standard mixers it should mix well – perhaps due
to its fineness it may take more time to mix in.
Are the glazes food safe?
They are lead free & hence food safe for all ware.
Is the slip easy to ‘set up’?
Yes – but as the body becomes vitreous it is very important
to be aware of entrapped air either as pockets in the cast piece or as bubbles
in the slip. Air in either form will cause bloating in the glaze firing.
Lead free glazes to suit White Midfire
