- The document discusses slag and hammerscale analyses from iron production sites in Scandinavia and other parts of Europe from different time periods. - The compositions of slag and hammerscale can be used to identify the iron production processes used at specific sites and how they changed over time and location. - Primary smithing, which involves smelting iron directly from ore, was common in the Iron Age and Viking Age but decreased after 1500 AD, being replaced by secondary smithing and welding.

1. Korrosion, slagger
og hammerskæl
Arne Jouttijärvi

2. FO204798 B
Korrosion i svejsninger og slagger
Galsted, HAM 2908x150
Galsted, HAM 2908x321
Grønnebæk, HAM 8252
FO211499 A

3. Intergrannular korrosion
1,7 % P
•
•
Medium fosforindhold
Ekstremt store korn
•
Ses normalt kun i
rustfri stål
Kan provokeres i
fosforholdigt jern ved
behandling i
kalciumnitrat ved 60 oC
•
FO204798 B
Ca(NO3)2, Norgessalpeter
FO201321 A
1,1 % P

4. Selektiv korrosion af stål
FO203595 B
FO208249
HEM 20/50
FO215230 B

5. Manglende stål
MHM 1355 x738 Büssow 14
2007/134,116
HOM2247x1707
Büssow 14
2007/134,10
FO208250
FO208272

6. Fosfor og
korrosion
7,9 % P
2,0 % P
3,0 % P
3,0 % P
7,7 % P
1,7 % P
1,2 % P
0,3 % P
3,5 % P
0,9 % P
1,1 % P
1,4 % P
1,8 % P
2,1 % P
0,8 % P
1,1 % P
1,3 % P
4,3 % P
1,8 % P
3,6 % P
0,6 % P
1,2 % P

7. Slag inclusions
97,5
95,0
FeO + SiO2
92,5
90,0
87,5
85,0
82,5
80,0
77,5
60
65
70
75,0
80
FeO
85
90
95,0
75,0
100,0
n=1862

8. Tietgenbyen, Odense. Viking Age

9. Welds in Viking Age
97,5
95,0
FeO + SiO2
92,5
x372 1
x378
90,0
x601
x372 2
x449
welds
87,5
85,0
82,5
x455
x492
80,0
x339 A
60
65
70
75,0
80
FeO
85
90
95,0
x278
77,5
75,0
100,0

10. Copenhagen. 14th to 17th century

11. Welds 14th to 17th century
97,5
95,0
FO203833
FO204834
FO203567
FO201913
FO209356
FO209356
FO202942
FO203595
FO212448
FO204838
FO204798
FO203016
FO215486
FO203821
FO203013
FO204834
FO212212
FO203493
FO203567
FO203567
FO204838
FeO + SiO2
• Most slag inclusions are
remnants of smelting slag
• Welding will leave some
inclusions
• Hammerscale might be
trapped in the welding
process
• The flux used changes from
Iron Age/Viking Age to the
Late Middle Ages. Probably
a switch from local sand to
60
65
70
well defined quartz sand75,0
or
burned flint
80
FeO
85
90
95,0
92,5
C
a
90,0
A
A
87,5
B
C
Ba
B
D
85,0
82,5
B
C
C
b
c
Bb
80,0
77,5
75,0
100,0

12. The origin of hammerscale
Process
Source
• Primary smithing
• Secondary smithing
(formimg)
• Welding
• Smelting slag in the iron
• Oxidation of the iron
surface
• Oxidation + flux
(sand, silica)

13. 1200
1000
900
800
700
600
500
400
300
200
100
0
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
• Primary smithing
20
18
16
14
12
10
8
6
4
2
0
• Secondary smithing
6
5
4
3
2
1
0

14. Hamerscale
45,0-50,0
40,0-45,0
35,0-40,0
97,5
30,0-35,0
25,0-30,0
20,0-25,0
95,0
15,0-20,0
10,0-15,0
FeO + SiO2
92,5
5,0-10,0
0,0-5,0
50,0
90,0
45,0
99,5
87,5
96,0
40,0
92,5
35,0
85,0
89,0
30,0
82,5
85,5
25,0
20,0
• The dominant process is secondary
15,0
smithing
10,0
5,0
• The composition oh hammerscale
0,0
80,5
makes it possible to 75,5 78 75,0 83the 8088 90,5
determine 85,5
60
65
70
FeO
processes used in a workshop
82,0
80,0
78,5
77,5
75,0
93
85
95,5
98
90
95,0
75,0
100,0
n=1791

15. Simple smithies
100,0
FeO + SiO2
95,0
90,0
85,0
80,0
Fors 28, Sweden, 18th century
75,0
60
65
100,0
FeO + SiO2
95,0
90,0
85,0
80,0
Rødbøl, Norway, iron Age
75,0
60
65
70
75
80
FeO
85
90
95
100
70
75
80
FeO
85
90
95
100

16. Workshops for
primary smithing
100,0
• Different forges for different
purposes
FeO + SiO2
95,0
90,0
85,0
80,0
SIM48/2009, Thorning, medieval
60,0
65,0
100,0
FeO + SiO2
95,0
90,0
85,0
80,0
Klosterbakken, medieval
75,0
60
65
70
75
80
FeO
85
90
95
100
70,0
75,0
80,0
FeO
85,0
90,0
95,0
75,0
100,0

17. Secondary
smithing and
welding
100,0
FeO + SiO2
95,0
• Primary smithing diappears
almost completly after 1500
AD
90,0
85,0
80,0
HAM1598, Stagebjerggård, medieval
60,0
65,0
100,0
FeO + SiO2
95,0
90,0
85,0
80,0
Guldager, medieval
60,0
65,0
70,0
75,0
80,0
FeO
85,0
90,0
95,0
75,0
100,0
70,0
75,0
80,0
FeO
85,0
90,0
95,0
75,0
100,0

18. Søndersø fall/winter 1022/23
•
•
•
•
Vitrified clay
Hammer scale & slag spheres
Movement in the workshop
The shadow of the blacksmith

19. The mapping of
smelting slags
• The slag resulting from a
smelting system will contain
oxides from ore, furnace
material and charcoal ashes.
• Alle of these will be
influenced by the local
geology.

20. Analytical
variation
2,0
1,8
1,6
1,4
K2O
1,2
FO203606
FO200760
FO200978
FO215477
1,0
0,8
0,6
0,4
0,2
0,0
0,0
1,0
2,0
3,0
4,0
5,0
Al2O3
6,0
4,0 7
7,0
3,5 6
3,0 5
2,5 4
K2O *
• The main reason for variation
is differences in FeO content
• Does not apply in the same
way to phosphorous
Al2O3
K2O
P2O5
2,0
FO203606
FO200760
FO200978
FO215477
3
1,5
2
1,0
• Can be minimized by only
looking at the gangue
(eliminating FeO from the
analyses)
1
0,5
0
0,0 0
50,0
5
60,0
10
70,0
Al2O3 *
15
20
80,0
25
90,0
100,0

21. Work done so far
• A total of 2310 analyses of well documented smelting
slags from app. 370 sites have been analysed
• Bivariate plots are used for visualisation of important
differences

22. The mapping of smelting slags
K2O
K2O
10
10,0
1
1,0
1
10
100
10,0
100,0
Serie15
North European Plain
Norway/Sweden/Central Europe
0,1
1,0
Al2O3
Al2O3
n=2310

23. The North European Plain
100,0
B1
C1
C3
CaO
B4
B3
0,10
10,0
1,0
1,00
MgO
10,00

24. 100,0
B1
Denmark
CaO
C1
10,0
0,10
1,0
1,00
MgO
• The younger moraine north
and west of the ice front
contains more lime
• The older material to the south
west is depleted of lime
10,00

25. Snorup
K2O
10,0
1,0
1,0
10,0
North European Plain
Norway/Sweden/'Central Europe
Snorup
0,1
Al2O3
100,0
• The variation within one site
can equal the variation within
the entire geographical area
• Differentiation between
individual semlting sites can
not be expected

26. Snorup
100,0
CaO
B1
C1
Snorup
10,0
0,10
1,0
1,00
MgO
10,00

27. Groups outside the North European Plain
10
A1
A2
A6
A7
TiO2
A8
1
1
10
0,1
Al2O3
100

28. heimdal@archaeometry.dk
• Please send more slag
(or analyses)

29. A2,98
A2,128
A2,129
A2,130
A2,122
A2,121
A2,127
A2,348
A2,344
A2,123
A2,105
A2,230
A2,255
A2,256
A2,70
A2,258
A2,259
A2,67
A2,243
A2,254
A2,252
A2,261
A2,264
A2,242
A2,245
A2,291
A2,288
A2,293
A2,289
A2,292
A2,287
A2,294
A2,285
A2,286
A2,290
A2,244
A2,253
A2,284
A2,246
A2,260
A2,68
A2,248
A2,257
A2,134
A2,135
A2,220
A2,247
A2,153
A2,154
A2,224
A2,324
A2,327
A2,424
A2,69
A2,222
A2,228
A2,223
A2,229
A2,225
A2,227
A2,347
A2,219
A2,266
A2,430
A2,431
A2,456
A2,432
A2,453
A2,454
A2,84
A2,86
A2,87
A2,364
A2,433
A2,341
A2,343
A2,20
A2,17
A2,325
A2,133
A2,449
A2,339
A2,221
A2,346
A2,138
A2,209
A2,443
A2,447
A2,451
A2,426
A2,442
A2,231
A2,263
A2,365
A2,132
A2,276
A2,16
A2,131
A2,367
A2,328
A2,337
A2,417
A2,342
A2,345
A2,19
A2,175
A2,226
A2,380
A2,393
A2,332
A2,137
A2,208
A2,440
A2,323
A2,326
A2,174
A2,335
A2,333
A2,407
A2,408
A2,334
A2,406
A2,139
A2,210
A2,391
A2,382
A2,383
A2,350
A2,338
A2,330
A2,336
A2,329
A2,331
A2,340
A2,384
A2,422
A2,416
A2,375
A2,349
A2,351
A2,274
A2,419
A2,420
A2,399
A2,394
A2,404
A2,377
A2,396
A2,359
A2,379
A2,387
A2,358
A2,371
A2,381
A2,401
A2,251
A2,378
A2,386
A2,388
A2,400
A2,402
A2,403
A2,376
A2,374
A2,418
A2,392
A2,412
A2,390
A2,370
A2,368
A2,369
A2,405
A2,421
A2,410
A2,411
A2,413
A2,415
A2,366
A2,414
A2,395
A2,361
A2,362
A2,360
A2,385
A2,389
A2,363
A2,373
A2,249
A2,372
A2,427
A2,428
A2,250
A2,423
A2,425
A2,434
A2,445
A2,397
A2,398
A2,409
A2,448
A2,444
A2,446
A2,452
A2,450
A2,439
A2,435
A2,437
A2,436
A2,438
A2,441
A2,85
A2,457
A2,125
A2,109
A2,429
A2,112
A2,107
A2,113
A2,108
A2,104
A2,110
A2,115
A2,116
A2,114
A2,118
A2,119
A2,101
A2,126
A2,103
A2,106
A2,100
A2,102
A2,124
A2,111
A2,117
A2,99
A2,120
A2,136
0
10
• Further division of the Central
European group will be possible

31. 0,7-0,8 % C
0-0,4 % C
Dejbjerg wagon, 1st century bc

32. 200-400 AD
• Western
Denmark
• Eastern
Denmark
70
60
50
40
C1
30
C3
B2
20
A2
10
A1
B1
0
A1
IMPORT
LOKALT
UKENDT

33. 800 – 1200
AD
• Western
Denmark
• Eastern
Denmark
70
60
50
40
C1
30
C3
B2
20
A2
10
A1
B1
0
A1
IMPORT
70
60
C3
50
B2
40
30
A2
C1
20
10
A1
B1
A1
0
IMPORT
LOKALT
UKENDT
LOKALT
UKENDT

34. The end