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This additive is a powdery solid, the color tone produced by which is similar to the SN-1, but much better in terms of stability and throwing power. It is an economic additive to reduce cost by 10% over.

1. Bath Composition (For make-up):

SN-2
NiSO₄·6H₂O
SnSO₄
H₂SO₄
Deionized Water

15-20g/L
20-30g/L
8-10g/L
18-20g/L
balance

2. Processing Parameters:

Voltage
Temperature
PH value
Time

15-18V
20±5℃
0.8-1.0
1-15min

3. Bath Maintenance:

(1) Analyze the content of free H2SO₄, SnSO₄, NiSO₄ and total acid value daily. The free H₂SO₄ should not be less than 18g/l and the total acid value should be kept in the range around 30g/l. Addition amount of SN-2 additive is 0.5-1.0kg per addition of 1kg SnSO₄.
(2) Add purified water slowly with agitation, so as to prevent the local hydrolysis of SnSO₄ which may cause the bath becoming turbid.
(3) After long period of production, there will be white sediment formed in the bottom of the tank that should be cleaned by filtration or decantation.