ANALYSIS OF ALUMINUM DYE BATHS
These procedures describe methods used for determining pH and concentration of a dye bath.
EQUIPMENT:
•
•
pH meter, e.g. Fisher Science Education model S90528
Spectrophotometer, e.g. Milton Roy Spectronic 21D
pH:
1. Calibrate the pH meter on a regular basis with at least two reference standards,
per the equipment manual.
2. Measure a cooled representative sample taken directly from the dye bath, and
record.
CONCENTRATION:
Calibrating the Spectrophotometer
1. Calibration must be carried for each new dye measurement.
2. Adjust the spectrophotometer wavelength to the appropriate value (Appendix 1)
and calibrate per the equipment instruction manual. This normally entails setting
the function dial to Transmittance and setting the display to zero, then inserting
the cuvette filled with water and setting the display to 100. Note that separate
dials are used to adjust these two set points.
3. Set the function dial to Absorbance.
Preparing an Absorption Curve (Appendix 2)
1. In the laboratory, prepare a dye standard of known concentration. Adjust the pH
to the target value. Dilute a small sample of this standard per Appendix 1.
2. Measure the absorbance using the calibrated spectrophotometer.
3. Prepare a straight line graph of Absorbance v Concentration using zero as the
origin.
Measuring Bath Concentration
1. Dilute a small amount of the production dye bath per Appendix 1.
2. Measure the absorbance using the calibrated spectrophotometer.
3. Using the Absorption Curve, determine the concentration of the bath using the
measured value.
Page 1 of 3
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Appendix 1
Wavelengths & Dilution factors
BLACK
λ
(nm)
Dilution
λ
(nm)
Dilution
Black BK Super
600
1:400
Blue A
597
1:100
Black BKA
580
1:300
Blue 4A
630
1:100
Black 2LW
610
Black VA
497
1:300
Blue 2LW
595
1:50
1:200
Fast Blue G
591
1:75
Black WH
600
1:250
Turquoise PLW
630
1:50
Black CRO
620
1:400
Black MLW
610
1:200
Violet CLW
560
1:75
Black H3LW
512
1:100
Violet 3D
477
1:7
Black HBL
580
1:200
Violet MRB
600
1:75
Black OA
645
1:400
MIL Taupe
570
1:20
Black GL
600
1:100
Brown BL
472
1:75
BLUE
VIOLET
BROWN
RED
ORANGE
YELLOW
GREEN
Bordeaux R
515
1:75
Brown GL
470
1:100
Bordeaux RL
515
1:75
Brown GSL
481
1:50
Fast Red B3LW
520
1:75
Brown R
395
1:100
Fiery Red ML
515
1:75
Yellow Brown 2G
501
1:50
Red GLW
520
1:70
Olive Brown 2R
583
1:50
Pink BLS
530
1:100
MIL Tan
450
1:30
Gold Orange RLW
400
1:100
Grey BL
583
1:18
Orange G
480
1:35
Grey NL
540
1:10
Orange 2B
400
1:150
Grey HLN
580
1:15
Orange C
400
1:150
Grey R
580
1:15
Orange RL
392
1:100
Orange 3A
480
1:35
Gold S
482
1:7
Gold L
467
1:50
Copper BF
495
1:40
GREY
METALLIC
Yellow 3GL
420
1:200
Yellow 4A
455
1:100
Bronze G
510
1:50
Yellow D
384
1:100
Bronze 2LW
460
1:25
Bronze L
490
1:25
Copper Penny
482
1:75
Green AEN
508
1:15
Green 3LW
479
1:15
Green AX
600
1:100
Green LWN
631
1:50
Olive Drab #9
590
1:50
MIL OD Green
450
1:50
Page 2 of 3
RELIANT ALUMINUM PRODUCTS, LLC
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520 Townsend Ave. · High Point, NC 27263 | Post Office Box 2364 · High Point, NC 27261 | 866-574-0790
Appendix 2
Example of an Absorption Curve
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