CERAMIC PROCESS AND RESEARCH BOOK TRANSFORMATION OF KÄHLER FABRIK Elizabeth Johnson
Contents
8
Introduction
12
Lustre Pigment lustre Resinate lustre
16
Method Time plan - Intention Process
26
Recipes Base glazes Top glazes
28
Test 01 Recipe - Results - Analysis - Graphs Conclusion
30
Test 02 Recipe - Results - Analysis - Graphs Conclusion
34
Test 03 Recipe - Results - Analysis - Graphs Conclusion
38
Test 04
42
Test 05
44
Test 07
52 54
3
4
Lustre; definition and techniques
Lustre colours Radiant or luminous brightness; brilliance; radiance. Ceramic lustre Extremely thin layers of metals fired onto the surface of clay producing a radiance and luminous brightness. The effect is due to the interference of incident and reflected light. Precious metal preparations and resinate lusters, in their unfired state, are complex mixtures of up to 40 components with different chemical and toxicological properties. It is usually characterized as metallic, glassy, pearly, or dull. There are two types of lustre firing which I will experiment with in order to produce the desired Kahler red lustre finish Reduced Lustre Glazes Lustre colouring forms on top of the surface of the glaze usually covering the entire form. Only the glaze surface is reduced, with the metals already part of the glaze; therefore you can refire back to glaze temperature allowing the surface to reoxidise. The key element to this method of lustre is the glaze; usually an earthenware, containing either singly or in combination; copper, silver and bismuth metals (in the form of carbonate, nitrate, sulphate and oxide) which when reduced will result in a lustre upon cooling. Bismuth is important when added to copper or silver but on its own is colourless and gives a mother of pearl effect. Reduced Pigment lustre The most common form of ceramic lustre; the result of reducing copper, silver and bismuth oxides with eartherware clay and applying the resulting mixture to a high fired (1060C) tin glaze surface. The metal compounds will transfer into the glaze during the reduction cycle; allowing the lustre colouring to form under the surface of the glaze. Three most important factors - pigment/base glaze, the length of reduction and temperature The piece is then refired and held in heavy reduction at a low heat (600-650C) allowing for a thin layer of metallic oxide to form on the surface of the glaze. After the firing wash the pigment off the earthenware and you will reval a nano-thick layer of iridescent metal where you applied the pigment. At low temperature, nothing happens, at too high the luster pigment sticks to the glaze and cannot be washed off.
5
Production timeline
Mold preparation Negative or positive form - CNC Plaster press mold Metal outline form for extrusion Clay preparation Choice of clay body - colour, structure etc. Wedging for correct consistency Production Press mold | extrusion Air drying 1-2 weeks to prevent tiles from cracking during firing Bisc firing - 960 degrees 6 hours to 600, 3hr 20m to 960 Base glazing Glaze tests - different base glazes Fritte tests Application - Paint | Spray | dipping | pouring Glaze firing - Earthenware at 1060 degrees 6 hours to 600, 3hr to1060 - hold for 20min, slow cooling Lustre glazing Double fire base glaze tests Glaze tests - Pigment and reduced Spray | dipping | pouring Lustre reduction firing Wood firing - 600-750C experiments Gas firing - 600-750C experiments Temperature and speed tests Reduction (Deoxidation) Takes place in the firing of ceramics with gas or wood. The oxygen in the kiln is reduced and / or eliminated and the smoke that is produced, (that contains particles of carbon or carbon monoxide) mix with the glaze and alter the colouring. Analysis Treatment to the surface of the glaze - Pigment lustre Cross analysis of changes in firing
6
Method and Process
Testing of frittes- melting points and running ability addition of Kvarts and Kaolin at 10-40g to 100g fritte use as transparent and mix with copper, coblat and tin at 1-4% 04. Fritte mix 1
05. Fritte mix 2
1 2
1 2
3
4
5
3
4
5
Kvarts + Kaolin 10-40g
Kvarts + Kaolin 10-40g 06. Fritte mix 1 and 2 1 2
3
4
5
Fritte 1
100
75
50
25
0
Fritte 2
0
25
50
75
100
K+K
10
10
10
10
10
7
8
Reduced glaze lustre firing 01 05.02.2015 In large combi kiln (no 2), Es incla inte hilleri ssilien atiam, conceporte, nota maximum fur. Im addum vividelut vertatus probse tus hocta consintimum perfina, temerit. Upertes ciendeo ractusp erbissedium hala mium consulus, in tum prissim ovemqui denteristra trudem publissi stesilla auro coendi, que et ademquo etimod se, clessa rei publici fauc fatiliis hostri, nossus hem. Vast vidi, Patum ines inam lissi sendum, sus simus susque nostid dius inpricas perivid ca; nonverei publibem st consult orescri, fors ex nemus consi sidiemq uonsulius o egerbissus. Castam. Rudam simuste is, consules tant. Lis hoc ticus horibus concut o moriptia cae factorum omnos interimum publiemus denirtest omactua iaecreo, et rem tante cla nonveruntion sendet Cupere con senatu coenatu es An desterf econsus obunu mus et faciorum arbem perte core co vivessintus; nu iam fue consume naterum enatusperit, que tercerfeces? Batrem niura Sciam lost gra ressess endamplium deperibem, quitid diis, quam di, ca rena, ver ut foruntium halicem patervi vaturni hilintertusa nostrari, quidi, catinem tudes
9
Test 01; tile sample layout
01. Transparent 1
2
4
5
6
7
8
9
02A. Tin oxide - 2% 1
2
4
5
6
7
02B. Tin oxide - 4% 8
9
1
2
4
5
6
7
02B. Tin oxide - 8% 8
9
03A. Coppercarbonat - 2%
03B. Coppercarbonat - 4%
1
1
2
4
5
6
7
8
9
2
4
5
6
7
8
9
8
04A. Copperoxide - 2% 1
2
4
5
6
7
8
04B. Copperoxide - 4% 9
1
2
4
5
6
7
8
9
8
05A. Coppersulphate- 2% 1
2
4
5
6
7
8
05B. Coppersulphate - 4% 9
1
2
05A. Coppersulphate (4%) and tinoxide (8%) 1
10
2
4
5
6
7
8
9
4
5
6
7
8
9
1
2
4
5
6
7
8
9
Recipes; Base Glazes
1: Fritte J Kaolin E
80 20
2: Fritte J Kridt Cornish stone Kaolin E
65 10 15 10
4: Fritte 3069P Barium carb Kvarts Aluminiumoxyd 5: Fritte J Barium carb Kaolin E Kvarts
71,5 21,0 3,5 4,0
72 15 4 9
6: Fritte J Lithium carb Kaolin E Kvarts
66 6 21 7
7: Fritte J Zinkoxyd Kaolin E Kvarts
66 6 21 7
8: Natron Feldspat Kvarts Lithium Carbonate Kridt SP Kaolin Bentonit 9. Ferro frite Petalite Bentonite
46 31 15,5 3 3 1,5 87 11 2
Additions of Copper carbonate, Copper oxide, Copper sulphate and Tin oxide.
11
Lustre programming schedule
Note; You have to press “UDSUGNING START” at the control panel before you can start the kiln.
Start the kiln the day before with time delay, so that the temperature will be 750 ͦ by 9 am for the reduction to start.
Program: 100 /ͦ hour to 750 ͦ, hold for 5 hours We stopped the kiln at 10 am after one hour holding at 750 ͦ. Then reduced with sticks for 1.5 hours while the kiln was cooling down to 640 ͦ. Note; top damper on kiln closed all the way from start to finish.
Note; Ventilation in Workshop leaders room put to max (Trin 10).
The dampers should be like this: Open to the next kiln and closed to the kiln far away. Make sure that all other dampers are closed - apart from damper for upstairs kiln which should face ‘aben’.
12
Use of Kiln 02; large combi kiln; gas and electric. Stack tiles vertically and flat to observe difference in firing; running of the glaze and different oxidisation.
Kiln fibre around door to prevent smoke escaping. Cut and prepped one large bag of dried sticks (6 large bundles).
16 small bundles inserted into kiln through front vent hole. Observed that colour of fire when from dark orange to very dark red. - Oxygen flame.
Opened the kiln the day after at 1 pm, at 200 ͦ. Kiln was loosly packed with a large open space in front for sticks to fall. Empty and vacuum kiln and elements.
Cone 019 (695 )ͦ Cone 018 (734 )ͦ Cone 016 (796 )ͦ
13
Test results; Copper oxide
01. Copper oxide tested at 2% and 4% on both red and blue clay. Overall red clay samples at 4% showed most promise and lustre effects than the blue clay and the 2% samples. Most successful glazes - 4,5,9 with 6 and 8 showing potential. 1 – 1/10 – overall unsuccessful 2 - 3/10 – overall unsuccessful, areas of shimmer on thicker applied areas – not much difference between 2% and 4% 4 – 7/10 – successful at both 2% and 4% on red and blue clay – shimmery red effect on thicker areas; with bronze shimmer on thinner areas – too thick areas turn to dark burnt copper look. 4- 7/10 on individual tile – most successful at 4% showing dark red finish. 5 - 7/10 – successful on 4% on red clay. Unsuccessful at 2% on blue clay. – lighter more pastel red effect on thick areas – bronze finish on thinner areas. 6 – 5/10 – successful at 4% on red and blue clay – matt red with bronzey shimmer on top layer. Unsuccessful at 2% 7 – 1/10 unsuccessful at both 2 and 4% on red and blue clay. – murky green colour. 8 – 5/10 – more successful at 4% on red and blue clay – dark red/purple shimmery effect – sporadic placing both on thick and thin layers. 9 – 7/10 successful at 4% on red clay on thinner applied areas – some areas still remain vibrant green. Unsuccessful at 2% on blue clay.
Before
14
After
Test results; Copper sulplate
02. Copper sulphate tested at 2% on both red and blue clay. Overall 4,5,6 and 7 showed the most potential at 2%. 1 – unsuccessful – colour changed to murky green/red 2 – unsuccessful – colour changed to dark green 4 – unsuccessful on group tile – flat tile double layer shows shimmer underlay. 5 - unsuccessful 6 – successful on red clay – shmmery red effect on thin layer – flat tile has no shimmer effect just matt red. 7 – successful both on blue and red clay – blue clay thin layer bronze shimmer effect. Red clay 8 – interesting broken effect of glaze on red clay (happened in first firing)– bronzey effect and dark red at edges. Unsuccessful on blue clay. 9 – unsuccessful – edges show redish glimmer
Before
After
15
Before
16
After
Test results; Copper carbonat
03. Copper carbonat – tested at 2% and 4% on red and blue clay. Overall results show that most of the glazes show signs of lustre apart from 4 and 8 which changed into a dull murky colour. 2% and thinner application showed stronger lustre effect. Difference in effect when stood up and lying down – lying down small samples showed lustre effect when nothing shown on standing tiles. Most successful 1, 2, 6, 7 and 9 at 2% on red clay. 1 – 4/10 bronze shimmer on thinner layers on blue clay tiles at 2%. Thicker layer on red tile shows bronze shimmer on 2%. Unsuccessful at 4%. 1 – 8/10 on individual small tile both 2% ans 4% – bronzey colourful shimmer 2 – 7/ 10 – successful on red clay at 2 and 4%. On thinner layers of glaze. unsuccessful on blue clay. 4 – need to test results 5 – need to test results 6 – 7/10 successful at 2% on red clay . unsuccessful on 4% on red and blue clay and unsuccessful on 2% on blue clay. Most successful on thinner layers. – vibrant red metallic effect. 7 – 7/10 successful at 2% on red clay – bronzy pink metallic finish on thinner layers. Unsuccessful AT 4%. 8 – 1/10 unsuccessful 9 – Thinner layers and edges show lustre potential – pale pink effect – most visable 04. copper carbonate and tin mix – 4% copper 8% tin. On both red and blue clay. The mix of tin into the glaze provides a most pearly effect of the lustre 1 – medium/ thinner layer on blue and red clay shows bronzey pink lustre finish 2 – medium/thinner layer on blue and red clay shows a pastel pink lustre finish 4 – medium layer shows listre effect on both red and blue clay - more vibrancy on red clay. 5 – thinner layer on red clay shows bronzey finish . no effect on blue clay. 6 - unsuccessful 7 - unsuccessful 8 – unsuccessful 9 – thin layer on red clay shows promise for vibrant red/bronze lustre finish.
17
Trial and error; explosion in kiln during fritte tests
18
Trial and error; melting of blue clay at high firing.
19
20
Lustre test 02
The second test will carry on the investigation of reduced lustre glazing from test 01 using the glaze results which showed the most promise Copper Carbonat -glazes - 1, 2, 6, 7 and 9 at 2 % Copper Oxide - glazes - 4, 5 and 9 at 4% Copper Sulphate - glazes - 4, 5, 6 and 7 at 2% Red and blue clay have been used but fired at different temperatures to test absorbancy and underlay colour on the effect of the lustre. Relief and texture will be tested on the clay tiles to see how the glaze runs and how the lustre reacts around corners and textures. The firing process The same firing program was taken as used in firing 01; with minor changes in temperature and time: 100 /ͦ hour to 750 ͦ, hold for 5 hours We stopped the kiln at 9.30 am after one hour holding at 750 ͦ. Then reduced with sticks for 1hour25minutes while the kiln was cooling down to 655 ͦ.- The kiln cooled down slower due to it being more heavily loaded with ceramics. Total of 19 bundles of wood inserted into kiln through front vent hole; using the reduction machine to measure how much the oxygen was reducing. Aim to hit around 4.0 reduction or less. Note: machine stops working every 5 minutes; must press the green button to reactiivate and measure an accurate reading. Opened the kiln the two days after at 12 pm, at 100 ͦ. Kiln was tightly packed but with a large open space in front for sticks to fall - some items were placed close to where the sticks fell but showed no signs of fire or ash damage upon opening. Cone 016 (796 )ͦ used at top and bottom of kiln; both indicated that temperature reached above this; this inaccurate result could be due to the length of holding the kiln at 750.
21
Lustre test 02; firing results
Before
22
After
Lustre test 02; notes from reduction process
New bundles of wood inserted into kiln each time the machine shows the oxygen has reduced -aiming for a redution of approximately 4.0 - using less wood than last time Bundle 1 - 4.2 reduction (big bundle) Bundle 2 - 17 in ten seconds down to 14, back up to 18.8 (big bundle) Bundle 3 - 14 reduction - 726C after 13 minutes (big bundle) - 723C after 15minutes Bundle 4- at 719C (3 sticks -1\3 bundle) - 2.5 reduction after 2minutes Bundle 5 - 717C (1/3 bundle - 4/5 thin sticks) reaches 4 reduction Bundle 6 - 714C (1/3 bundle) at 5 at 25 minutes into reduction Bundle 7- 710C didn't go up - 1.6 Bundle 8- 709C - 1 minute after bundle 7 at 5.6 reduction - went up to 7.8 after 1 minute - perhaps the bundle from 7 just became active. (?) Bundle 9 - 704C - (30 minutes into reduction) 4 fat sticks - 6.6-7 reduction Bundle 10 - 700C - 4 sticks - held at 6-7 Bundle 11 694C - 40 minutes into reduction stop measuring reduction on machine Bundle 12 -690 after 45minutes Bundle 13 -every ten minutes Bundle 14 1 bigger bundle after 10minutes Bundle 15 - 670C after 5 minutes - 2.6 bigger bundle Bundle 16 - 664 reduction point of 2.0 Bundle 17 -reduction point of 3.1 - 4 sticks put in when reduction was at 0.5 Bundle 18- 2.5 reduction at 658C after 1hr25mins Bundle 19 - last reduction
23
Copper oxide; glaze 4, 5 and 9
Before
After
No results for glaze 5 and 9, glaze 4 showing lustre on far right tile - third column.
24
Copper oxide; glaze four
Before
After
Opposing results appeared on different tiles for glaze 4; copper oxide - due to location in the kiln - will refire tile on far left to see what happens at different reduction process.
25
Copper oxide; glaze 5
Before
After
Mixed resuts across tiles - depending on location in the kiln
26
Copper oxide; glaze 9
Before
After
No change apart from fulling of the copper colour - will refire again to see if lustre appears in different reduction process
27
Copper carbonat; successful results
28
Copper carbonat; glaze 1
Before
After
The most successful results of all the glaze tests- working at all situations in the kiln Successful on both red and blue clay but producing a different hue of red lustre. Relief on the tile provoked the lustre to shimmer on the edges and provided different angles for the light to reflect off.
29
Copper carbonate; glaze 2
Before
After
This firing provided no results for glaze 02 and copper carbonat despite showing promise in the last round. This could be due to the temperature and position of the tiles in the kiln as all these tiles were sitauted at the bottom which the cones showed to have a higher temperature. I will refire these tiles in the next test.
30
Copper carbonat, glaze 6
Before
After
Glaze 6 showed areas of lustre on the middle blue clay tile in the photo above; this tile was situated at the top of the kiln. The identical tile (far right) which was sitauted at the bottom of the kiln showed no signs of change.
31
Copper carbonate; glaze 7
Before
After
Successful results -
32
Copper carbonate, glaze 9
Before
After
Mixed results -
33
Copper sulphate; glazes; different thicknesses; red and blue clay
Before
After
No change on glazesl 4, 5 or 6 but successful copper lustre effect on glaze 7 on all thicnkeses of glaze application.
34
Copper sulphate; glaze 4
Before
After
No change - will refire at diferent reduction process.
35
Copper sulphate; glaze 5
Before
After
No change - will refire at diferent reduction process.
36
Copper sulphate; glaze 6
Before
After
No change - will refire at diferent reduction process.
37
Copper sulphate; glaze 7
Before
After
Despite showing success on the mixed glaze tests there was no lustre effect on the blue clay tile above; this could be due to location in the kiln - I will refire to see if it changes at a different reduction process. Hiwever the red clay tile with relief showed definite lustre effects; with the edges from the pattern enhancing this effect.
38
Conclusion
Unsuccessful
Successful
The results showed huge potential on some of the glazes; especially copper carbonate. The placement of the ceramic samples within the kiln indicated that a difference in temperature could effect the lustre effect; with the tiles at the bottom of the kiln showing almost no change in colouring, compared to the dramatic changes of the tiles at the top of the kiln.
39
Before
40
After
Lustre test 03 ; 150318 march 19th 2015
Re-firing of previous tiles which did not become lustred due to placement in the kiln and reduction temperature and time. - Bundles approx every 3 minutes - new bundle put in when it reaches 0.3 again Firing three programBundle 1- no increase 3 sticks Bundle 2- no increase Bundle 3 - 0.6 increase - 6 sticks Bundle 4 - 1.8 increase - 6 sticks Bundle 5- 6 sticks - 2.6 increase Bundle 6 - 2.6 increase 6 sticks Bundle 7- 5 sticks 0.9 increase Bundle 8- 6 sticks - 2.4 increase -714C Bundle 9- 6 sticks - 2.4 increase Bundle 10-5 stick - 0.6 Bundle 11- 5 big sticks - 4.2 increase - probably due to the lack of increase in previous bundle - 25mins reduced to 705 C Bundle 12- - 5 sticks - 2.9 - start to use less sticks Bundle 13- 3 sticks - 1.3 increase Bundle 14- 3 big sticks - - 1.3 increase -30minutes 695C Bundle 15 - 4 sticks - 1.2 Bundle 16-4 sticks - 1.7 increase Bundle 17 - 4 sticks - 2.3 Bundle 18- 4 sticks - 3.6 45 mins at 680C Bundle 19- 4 sticks - 0.7 Bundle 20-- 4 sticks 0.6 Bundle 21 - 4 sticks - 0.3 Bundle 22 4 sticks - 0.6 increase Bundle 23- 3 big sticks - 0.3 increas Bundle 24- 5 sticks - 3.0 increase 1hr at 672C Bundle 25 - 4 sticks - 0.7 Bundle 26 - 1.1 increase - 5 sticks Bundle 27 - 6 sticks - 0.9 increase -658C actor 1hr10mins Bundle 28 - 5 sticks -655 after 1hr15minutes No results when opening kiln 2 days later - immediately refire back up to 750 and re duce again. Kiln appears to have been hotter at the bottom of the kiln with three of the cones melting at the bottom compared to two at the top.
41
Stoneware bowl before and after
42
Lustre firing 04; 150322; March 22nd 2015
Thid refiring of tiles from test 02, plus addiitonal earthenware, porcelain and stoneware tests samples Firing Four - 17.45 bundles with 5 minutes inbetween Insertion of more kiln stacksin to eat some of the heat - analysis that we don’t have the shelf in the middle which could be reason for less reduction and for it being hotter at the bottom Bundle 1 - large bundle at 750C - 2minutes to insert wood- sticks wet this time Bundle 2- 734c - large bundle -1 minute to insert wood - 3.4 co2 measurement Bundle 3 - 725C - large bundle - - 1 minute to insert - 8.4C - 16.0- 23.0 - Stop using the carbon dioxide monitor as seems inaccurate readings Bundle 4- 715C - large bundles- 1 minute insert Bundle 5- 705C - large bundle Bundle 6 - 697C - large bundle 18:15 Bundle 7-693C - large bundle - seems to be reducing at same time as last firing Bundle 8 - 685C - large bundle - 18.25 (40minutes) Bundle 9- 677C - large bundle Bundle 10 - 672C - large bundle Bundle 11- 669C - 55minutes in -large bundle 665C after one hour Bundle 12- 663C - large bundle Bundle 13- 660C - large bundle 1hr10mins Bundle 14 - 653C - large bundle Bundle 15 - 648C - large bundle Bundle 16 - 647 - large bundle -1hr25min
43
Test 04; Glaze 02; Copper carbonat
Before
After
The red clay tile with relief pattern was successful on red clay and proved to have a smore successful lustre on the relief tile.
44
Test 04; Glaze 01; Copper carbonat
Before
After
All tiles with glaze 01 and 2% copper carbonat were successful in the fourth firing test. Bottom left tiles glaze was applied with paint brush which gives it the subtle line reflief which plays with the lustre reflection nicely. - This tile is the same as the middle tile in top image - this shows how much the angle and light can change the glaze. Bottom right tile glaze applied with spray gun which gives it a more even finish
45
Test 04; unsucccessful sulphate results
Third refiring of the sulphate tiles again showed little to no change on both red and blue clay test tiles.
46
Test 04; unsucccessful oxide results
Third refirong of copper oxide tiles again showed little promise for lustre effect at all locations in the kiln. instead a dulling and muddying of the original viibrant glaze; this could be due to the temperature and reduction process.
47
Test 04; porcelain detail sketch models
Porcelain detail tests - high bisc fired - 1240 then low glaze fired - 1060 using glaze 01; copper carbonat 2%. Showed successful lustre finish.
48
49
Test 04; reduced lustre glaze
To create a reduced lustre glaze equal parts of copper carbonate and ocher are mixed with water (or vinegar) into a paste-like consistency. The paste is brushed onto an already glazed object. Typically low fired earthenware tin glaze (see image opposite). Typical for earthenware to be fired at around 700C, Porcelain around 800C. Advised by Peder Rasmussen on two different reduction methods 1 -Fire in oxidizing atmosphere to maximum temperature, then reduction for half an hour. 2- Fire in oxidizing atmosphere to maximum temperature, turn down the fire so that the kiln cools slightly, then reduction for 3-5 hours while the kiln is slowly cooling down.
Luster pastes for reduction (Artigas) 1 (1034) Copper carbonate 52 2, 3 g Red ocher 98 4, 3 g 2 (1037) Silver nitrate 15 0, 3 g Red clay 40 0, 8 g Red ocher 160 3, 2 g 3 (1041) Black cobber oxide 5 Iron oxide 12 Red ocher 4
1, 25 g 3, 0 g 1, 0 g
4 (1042) Copper sulfate 18 Tin oxide 22 Red ocher 50
1, 13 g 1, 38 g 3, 13 g
5 (1046) Cobber oxide 10 Copper sulfate 3 Yellow ocher 5 2, 0 g
50
4, 0 g 1, 2 g
6 (1053) Cobber sulfate 15 Tin oxide 10 (Kønrøg 1) Red ocher 20
3, 0 g 2, 0 g (0, 2 g) 4, 0 g
7 (1056) Cobber oxide 8 2, 0 g Iron sulfate 5 Iron oxide 6 Red clay 6
1, 25 g 1, 5 g 1, 5 g
8 (1057) Cobber oxide 5 1, 25 g Silver nitrate 2 0, 5 g Iron oxide 2 0, 5 g Red clay 8 2, 0 g 9 (1058) Silver nitrate 2 Cobber oxide 5 0, 5 g Cobber sulfate 5 (Coal powder 5) (0, 5 g) Red ocher 30 Redclay 8
0, 2 g 0, 5 g 3, 0 g 0, 8 g
1: Fritte J Kaolin E
80 20
2: Fritte J Kridt Cornish stone Kaolin E
65 10 15 10
4: Fritte 3069P Barium carb Kvarts Aluminiumoxyd 5: Fritte J Barium carb Kaolin E Kvarts
71,5 21,0 3,5 4,0
72 15 4 9
6: Fritte J Lithium carb Kaolin E Kvarts
66 6 21 7
7: Fritte J Zinkoxyd Kaolin E Kvarts
66 6 21 7
8: Natron Feldspat Kvarts Lithium Carbonate Kridt SP Kaolin Bentonit 9. Ferro frite Petalite Bentonite
46 31 15,5 3 3 1,5 87 11 2
51
Tin 2%
Tin 4%
Tin 8%
52
Reduced lustre results ; test 04
Translucent (situated in bottom and middle of kin Not many results as the pastes need an oxide to react with – glaze 2, 8 and 9 show the most potential for lustre reaction . Glaze 2 - showing pearlescent finish across all paste types Glaze 8 – 2, 4, 5 – (middle) - paste 2 showing gold colour underneath paste paste 4 showing areas of red lutsre, Paste 5 showing copper oxidization reaction( not lustred but perhaps at cooler temperature it will) , pase 9 Glaze 9 – paste 2, 5 and 9 (middle) Paste 2 – gold shimmer appearing under paste – thinner layer should be applied Paste 5 – rec copper oxidization apparent Paste 9 – dark gold lustre effect Tin oxide – 2% (1-5 at middle 6-9 at top of kiln) Paste 2 worked across most of the glaze types – creating a gold shimmer effect. – glaze 1 and 2 most successful – showing pearlescent goldy shine. Glaze 1 – paste 2 Glaze 2 – paste 2 Glaze 6 - paste 2 , paste 6 Glaze 8 – Paste 2 , paste 4, paste 6 (paste 5 green copper colour – potential at lower temperature) Glaze 9 – paste 2 , paste 5, paste 6, paste 9 (potential) Tin oxide – 4% (both placed in bottom of the kiln) – temperature was higher at the bottom – Potential that it would be more successful at cooler location within the kiln. Paste 2 worked across most of the glaze types – creating a gold shimmer effect. – glaze 1 and 2 most successful – showing pearlescent goldy shine. Glaze 8 and 9 showing heavy reaction to pastes – rusting of the metals appearing and hard to wipe off. Glaze 8 – paste 1 - red lustre appearing under surface but too tick layer to wash off completely – heavily rusted on top of the paste. Paste 2 – gold shimmer underneath paste – wont wipe off completely. Paste 4 – showing areas of deep red lustre Paste 5 – copper oxidization appearing on thinner glazes areas – green in thick glazed areas Glaze 9 Paste 2 – gold shimmer effect Paste 5 – successful red lustre finish Tin oxide – 8% - glaze too thick and tin quanitity too high for lustre paste reaction Glaze 9 – paste 2, 4 and 5 showing areas of lustre potential.
53
Reduced Lustre test 04 ; conclusion
Results from reduced lustre pastes on glazes 1-9 (3 not included) - fired in same process as lustre tiles – 750 then Reduced to 640… tiles situated across the kiln to see how temperature effects differently. – temperature was higher at the bottom of the kiln as this is where the ash burnt.. Thinner area is better for reaction as easier to wipe off with water and a sponge – if too thick the paste will stick to the glaze and you will not be able to wipe away to reveal the potential lustre result. Results from the reduced lustre pastes showed promise for some of the combinations of glaze and pastes. For the next lustre firing I will continue to test the following glaze and paste combinations Glaze 1 Glazs 2 Glaze 8 Glaze 9 Paste 9 Paste 6 Paste 4 Paste 5 Paste 2
After firing; pastes unwashed
54
After firing; pastes removed revealing metal lustres
Lustre test 05; 150328
Testing a combination of reduced lustre tiles and the most successful earthenware glazes from previous firings - Carbonate - glaze 01 and 07, Copper oxide - glaze 04 Firing process: fired up to 750 over 5 hours - held for 1hr 45min Large bundles of mixed wet and dry wood every 8 minutes (same size as firing 04) Shelf placed in the middle for the sticks to burn higher and give a more even reduction Cones at top and bottom of kiln Ceramics distributed around the kiln at different heights to test exposure results Potential for better results when facing towards the reduction flame. Bundle 1 – 750c - 17.08pm Bundle 2 – 728C 17.16 – reduced to 724 Bundle 3 – 712C – reduced to 710 - fames visable ad smell of burning wood Bundle 4 – 698 – reduced to 697C (24minutes in 17.32) – cooling fatser ecause less items in the kiln ? Bundle 5 – 687C reduced to 685C – flames and smoky smell – Bundle 6 – 678C C – temperature reduced to 676 (40minutes) - 10C lower than last time. Bundle 7 – 669C – dry sticks setting on fire – lots of smoke and flames Bundle 8 – 662 C (54minutes) Bundle 9 – 657C – reduced to 655C (1 hour) Bundle 10 – 652C – reduced 650C Bundle 11 – 645C – reduced to 644C Bundle 12 – 639C – 638C – Bundle 13 – 634C – reduced to 632C. – Last bundle at 1hr 32minute Unsuccessful firing for the earthernware lustre tests - with only 2 showing slight lustre finish - will refire again at a different reduction process.
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Reduced lustres; before
Reduced lustres; glazes 8 and 9 after reduction
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Lustre test 05; reduced lustres
Glaze 1 Glazs 2 Glaze 8 Glaze 9
Paste 9 Paste 6 Paste 4 Paste 5 Paste 2
Glaze 1 and glaze 2 with 2% tin showed none or very little change with any of the applied pastes (2,5,4,6 and 9). (re-fire with glaze 9 on top) despite different location in the kiln. Glaze 9 - paste 9 - slight underlying pearcelscent gold effect - paste has stuck on Glaze 9 - paste 6 - slight yellowish tint - no big change Glaze 9 - paste 5 - successful two different effetcs from different location in the kiln 1 - light pink / copper lustre effect and 2 - dark copper lustre results on edge of tile - burnt glaze (black in certaun lcoations) Glaze 9 - paste 4 - successful - copper gold linear effect - showing pearlescence on thinner layers of glaze - where applied with paint brush. Glaze 9 - paste 2 - successful shimemry gold effect - with pearlescent shine - paste has stuck on areas of the tile where glaze applied more thick. Re-try - glaze 9 with paste 5,4 and 2 - again with different locations in the kiln. Glaze 8 - paste 9 - gold effect on thinner glaze area Glaze 8 - paste 6 - unsuccessful Glaze 8 - paste 5 - copper / gold lustre effect - light burning of the glaze in areas. Glaze 8 - paste 4 - unsuccessful Glaze 8 - paste 2 - successful - dark gold lustre effect appaearing on thinner applied paste area. - different location in the kiln produc different gold hue. Re-try glaze 8 with paste 2 and 9(?) at different temperatur and kiln location.
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Smoke reduction
1 large bamboo bundle
Detail tests: before
Detail tests; after - over reduced
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Firing 06, lustre test; 150413
Observations Held for 3hours at 750 - 100C every hour up to 750. Recution over 1 hour and 43 minutes with 1 large bundle of bamboo inserted every 5 minutes which coresspinded with every 5C - total of 18 bundles of bamboo. The bamboo burns much qucker than wood we have previously used and produces alot of smoke upon immediate entry to the kiln. Smoke can be observed escaping from the back vent and through the insulation at the front door of the kiln - hopefully a sign of a heavy reduction happening. Used a total of 1 curtain worth of bamboo Started smoking slower at lower temperature - from bundle 14 onwards. Bundle 1 - 10.30am - 750C - quickly reduced to 740 during insertion of sticks. Bundle 2 - 10.35 - 736C - need longer sticks as short ones burn immediately. Bundle 3 - 731C smoking out of vent hole - need to hold the vent stopper firmly. Bundle 4- 725 Bundle 5 - 717C Bundle 6 -712C Bundle 7 - 706C Bundle 8 - 700C Bundle 9- 695C Bundle 10- 690 Bundle 11 - 685 Bundle 12 - 680 Bundle 13 -675 Bundle 14 -670 Bundle 15 - 665 Bundle 16 - 660. Bundle 17- 655 Bundle 18- 650 - Still smoking at 647C Results - murkey dusty results - over reduced - too smokey - potential shown in Bentes silver and gold lustre test samples - retry with same reuction cycle but smaller bamboo bundles.
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Before
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After
Fiirng 07; 150423
Smaller bundles every 5degrees (every 5 minutes) - until same temperature 650 Red lustres should devlop after 8th cycle - 1 cycle + 3 bundles every 5 minutes for greg daly. lightly packed kiln - shelves in same situation ceramic evenly distributed from top to bottom Sticks inserted all at once - last firing sticks were inserted in smaller bundles - potential for a less even reduction. bundle increased from 10 sticks to 14 sticks half way through cycle - only used half the amount of bamboo as last time - something to observe. can see little smoke escaping from back vent - Not as much as last time 10 sticks broken in half = 1 bundle Bundle 1- 750 C Bundle 2 - 738C Bundle 3 - 729 Bundle 4 - 722C Bundle 5 - 717 C - observed that temperature rises 1C after every bundle Bundle 6 - 713 C Bundle 7 - 708C - now start to reduce at every 5C drop in temperature. Bundle 8- 703 (4minutes) Bundle 9 - 698 C (30minutes) Bundle 10 - 693C - 12 sticks broken in half Bundle 11 - 688C - 14 sticks Bundle 12 - 683C - 14 sticks Bundle 13 - 678C (1 Hour into firing ) Bundle 14 - 673C Bundle 15 - 668C - went down to 666 then up to 669 Bundle 16 - 663C Bundle 17 - 658 Bundle 18 - 653C - 1 hour 40 minutes - doesnt appear to be burning anymore Successful results throughout the kiln; tiles on the bottom showing a heavier reduction with a slight dulling of the red lustre colour. Unsuccessful tiles due to application of the glaze onto the tile surface - spray application means the glaze is less dense and has an even surface which does not play well with the relief wanted by the lustre. Rec clay showed much more successful results than blue clay - potentially due to the iron in the raw cay.
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Lustre results on red and clue clay
Before
After - Glaze 4 successful result
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Results of the same red clay tile with Glaze 01 (2% copper carbonat) at different locations in the kiln - Bottom | Middle | Top. Middle tile had a burnt bamboo string stuck on it which has left the unreduced copper glaze apparent.
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Firing 07; 150430
Sticks inserted every 5C drop – total of 19 bundles – between 35-37g of wood Bundle 01 – 17.10 pm – 750 bundle 14 sicks Bundle 2 – 745C 0 17.13pm – 14 sticks Bundle 3 – 740C – 17.16 – 14 sticks Bundle 4 - 735C – 17.19 Bundle 5 – 730C –1 7.21 Bundle 6 – 725C – 17.23 Bundle 7 – 720C - 17.27 Bundle 8 – 715C – 17.31 – starts to go up 1C when insertedwood bundle )6 dark sticks) – gone up to 714 after 5 minutes? Bundle 9 – 710C – 17.37 Bundle 10 – 705 – 17.39 – quick drop in temp – see smoke escaping Bundle 11 – 700C – 17.45 Bundle 12 – 695C – 17.49 Bundle 13 – 690C – 17.55 Bundle 12 – 685C – 18.00 Bundle 13 – 680- 18.04 Bundle 14 – 675 – 18.10 Bundle 15 – 670 - 18.17 Bundle 16 – 665C - 18.22 – smoking sluightly later than previous firing – 10 secnds after inserting wood Bundle 17 – 660 C – 18.30 Bundle 18 – 655 – 18.37 Bundle 19 – final bundle – 650C Observations – smoking starts slightly later than previous firing; still apparent from back vent. Overall temperature dropping faster than last time – potentially due to density of the items in the kiln.
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Final models; extruded process
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