Determination of Free Potash concentration in Bronze baths

In alkaline bronzing processes, free potash plays a crucial chemical role: it keeps tin in solution - preventing it from precipitating -and balances its co-deposition with copper.
Analyzing this parameter allows for monitoring the active concentration of hydroxides in the bath. To ensure optimal efficiency and finishes free of cosmetic defects, the value must be strictly maintained within the operating ranges, which differ depending on whether white bronze or yellow bronze is being produced.
Since potash is naturally consumed as it reacts with atmospheric carbon dioxide (carbonation), frequent analytical monitoring is essential to restore the correct concentration and ensure absolute color consistency in the finished product.

Method

Test type: End Point.

Testing time: immediate reading.

Analysis sessions with multiple samples are possible up to a maximum of 16 tests for CDR GalvanLab^® and 3 tests for CDR GalvanLab^® Junior.

Step 1/13

Perform sample attivation. Take 50 µl of sample and place it in a cuvette containing the activator, close the cuvette and mix. The proper working procedure is described in the following slides.

Step 2/13

Collect 50 µL of sample with a pipette. Use a new tip for each test to prevent contamination from previous samples.

Step 3/13

Carefully clean the outside of the pipette tip with blotting paper, avoiding contact between the extremity of the tip and the paper.

Step 4/13

Place the sample in the activation cuvette. Keeping the tip immersed in reagent, press and release the piston of the pipette several times.

Step 5/13

Gently shake the cuvette 2-3 times.

Step 6/13

Place the test tubes containing reagent R1 in one of the incubation cells and let them warm for at least 5 minutes.

Step 7/13

Gently shake the cuvette 2-3 times.

Step 8/13

Place the cuvette in the cell marked with the blue light and press READ to perform the photometric reading.

Step 9/13

Collect 50 µL of extracted sample with a pipette. Use a new tip for each test to prevent contamination from previous samples.

Step 10/13

Carefully clean the outside of the pipette tip with blotting paper, avoiding contact between the extremity of the tip and the paper.

Step 11/13

Place the sample in the cuvette. Keeping the tip immersed in reagent, press and release the piston of the pipette several times.

Step 12/13

Gently shake the cuvette 2-3 times.

Step 13/13

Place the cuvette in the cell marked with the blue light and press READ to perform the photometric reading.

Sample treatment

The analysis is carried out on bronze bath. The sample must be previously treated with an aliquot of activating solution in cuvettes.

Principle of the test

The free potash value is determined by the reaction between hydroxide ions in the galvanic bath and a chromogen. The optical intensity is proportional to the concentration of hydroxide ions in the analyzed sample.

Calibration curve

Calibration curve was obtained by correlating the CDR method with the reference method.

Reagent test Kits

Free Potash on White Bronze Baths

Code *400180: 100 test
Code *400185: 10 test
The reagents have a shelf-life of 12 months

Free Potash on Yellow Bronze Baths

Code *400390: 100 tests
Code *400395: 10 tests
The reagents have a shelf-life of 6 months

Measuring range

Analyses	Measuring range	Resolution	Repeatability
Free Potash white bronze	0.5 - 10 g/L	0.1 g/L	0.1 g/L
Free Potash yellow bronze	12 - 50 g/L	0.1 g/L	0.7 g/L

The chemical analysis instruments for electroplating baths

CDR GalvanLab®

Complete analysis panel, supplied already configured
Up to 16 determinations simultaneously
Possibility of carrying out analyses of the same sample
Integrated printer
Full connections (LAN - USB - Bluetooth barcode/QR code reader)

CDR GalvanLab® Jr

Partial analysis panel, customisable configuration
Up to 3 determinations simultaneously
Wireless connection to external printer
USB connections

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