Dremel 876 Specifications download pdf (Page 26)

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Problems & Solutions

Firing

Problem Cause Solution

Blisters, craters and pinholes in glaze.

a. Bubbles formed and glaze cooled

too quickly.

b. The glaze was fired on immature

bisque.

a. Allow kiln to cool slowly, soaking

the kiln. (Turning the kiln back on

low for 1 hour after the kiln has shut

itself off.) This allows the glazes to

heal after the kiln has shut off. Do

not leave kiln unattended.

b. Bisque should be fired two cones

hotter than the glaze.

Reds develop darker spots in the color.

a. Too heavy of application of color.

b. Insufficient amount of oxygen for the

glazes to develop during firing.

a. Four coats of color is required for

proper application.

b. Keep kiln propped until the kiln goes

onto high. Allow extra room around

all pieces, including the stilting of

the piece and the shelves above. Do

not place all like sized articles on

one shelf during the firing.

Plates have dark gray areas in the

middle.

Unburned carbon not removed from

the ware.

Do not stack pieces inside one another

during the firing. Allow for proper venti-

lation and air circulation during the firing

process. If piece has not been glazed,

can be corrected by refiring the piece to

one cone hotter. Then glaze as normal.

Greens migrate to light colored glazes.

Called oxidation (fuming, shadowing

or flashing) where the oxides in the

glaze migrate during firing.

Allow the pieces extra room when

loading the kiln. Fire greens on top

shelf when possible. Some colors are

more susceptible than others, make a

test to ensure this does not happen. Do

not mix color companies' products

without a test first.

Reds have turned gray.

a. Insufficient amount of glaze on piece.

b. Poor ventilation and air circulation

during firing can greatly affect the

color.

c. Overfiring of piece.

a. Apply 4 heavy coats of color.

b. Allow proper ventilation and

placement of pieces in the kiln during

firing.

c. Fire reds to shelf cone 06. Do not

soak or slow fire the colors if possible.

Gloss glaze is matte.

This is underfired glaze.

Fire to the shelf cone mandated on glaze

label. Do not fast cool the glaze firing.

Glaze crackles or crazes after firing.

a. Immature bisque.

b. Glaze and body fit problem. This is

called "coefficient of expansion" of

the glaze to the clay.

a. Make sure the bisque is fired to the

appropriate shelf cone for that clay to

mature the ware.

b. Make sure glaze can be fired on that

type of clay.

Pieces melted during the firing.

Kiln overfired.

Check kiln system to make sure every-

thing is in working order. Kiln should be

cleaned before each firing. Go periodic

checks and maintenance of the tube

assembly and shut off hammer. Never

leave kiln unattended while to avoid this

problem.

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